A few weeks ago I wrote about clearing tomato plants, and mentioned our hoophouse troubles with nematodes. Nematodes are tiny soil-dwelling worms that have a wide host range and are hard to control. They move only 3’–4′ (1–1.2 m) per year on their own, but people move them on shoes, tools, etc. We have had peanut root-knot nematodes (Meloidogyne arenaria) since 2011 when we found them in spinach transplants we were growing for outdoors in early spring.
In my August 2014 post Good news – great hoeing weather! Bad news – more nematodes in the hoophouse I wrote about solarization to fight nematodes in our hoophouse (scroll down to the end of the post). The post includes a photo of our first attempt at solarizing – a bit of a How Not To! Be sure to use UV-inhibited polyethylene. This year we somehow got some construction plastic mixed in. It doesn’t work! It goes cloudy (thus not heating up the soil) and it shatters into little pieces.
My most thorough blogpost about nematodes was in 2018 for Mother Earth News: Managing Nematodes in the Hoophouse.
My postSolarization and crop choices to fight nematodes in August 2019 includes a photo of a much better way to solarize an individual bed. In that post I gave a list of nematode-resistant food crops, and also talked about cover crops. There is a photo of nematodes on cucumber roots there too).
Food crop choices to fight nematodes
Most resistant and most helpful are the Juncea group of mustards. I did some research into more Juncea options in Solarization and crop choices to fight nematodes. We don’t like very pungent greens, so we have not yet taken the route of planting a whole bed of Juncea types. Instead we have mapped and flagged the nematode-infested areas of our beds, and try to be mindful of what we plant in those spots. Three of our seven beds have no nematodes so far.
This year we looked at the nematode map we had made and decided to focus our attention on the bed with the highest number of nematode patches, and grow the most resistant winter crops (of the ones we like to grow) there. That’s the frilly mustards (Ruby Streaks, Scarlet Frills, Golden Frills, all Juncea mustards, and Mizuna, a Japonica mustard), Yukina Savoy (variously reported to be Brassica juncea, Brassica rapa pekinensis, and Brassica rapa), and Russian kales (Brassica rapa).
Mapping nematode areas
See the post with info from Gerry Ross I mentioned above. We have previously tried for a “Two years good, One year bad” strategy. This was to grow nematode-resistant crops in the infected areas for two years, then try risking one year of susceptible crops. That was a bit demanding on careful management, and we haven’t kept that up.
A reader asked about cover crop choices to fight nematodes. In June 2019 I wrote about using marigolds, sesame, Iron and Clay cowpeas as warm-weather nematode resistant cover crops. We’ve also used winter wheat (in winter!), and white lupins (not worthwhile, in my experience). See that post for a few other ideas on nematode-fighting cover crops, and why we decided against some options. At that time, we decided not to grow sunnhemp (Crotolaria) because it is poisonous, although newer varieties of Crotolaria have lower toxin levels. More recently we have been growing sunnhemp, after I saw it growing so well in North Carolina. It is a warm-weather legume, so it is feeding the soil while tackling the nematodes. It does grow tall in the hoophouse, and we have taken to chopping it down with hedge shears to an ergonomic elbow-height every few weeks whenever it gets too tall. The cut tops create a nice “forest-floor” mulch effect. You can almost feel the extra organic matter nurturing the soil! (High OM levels deter nematodes.) 60-90 days to maturity.
We previously used soybeans as a short-term leguminous summer cover crop, but they do not offer the nematode resistance. Iron and Clay, Mississippi Silver and Carolina Crowder cowpeas are all nematode-resistant and can be grown in summer instead of soybeans. Sesame is a legume that is particularly good against peanut root-knot nematodes.
A Florida reader gave me information about partridge peas, which I have not yet tried: After terminating cool-season brassicas and celery between April and June, their late spring sowing of partridge peas were too late this year to be productive, because the hard seed was very slow to germinate. Partridge pea could be a good cover crop for mid- to late-summer, if you scarify those hard seeds to speed germination.
Some cover crops can be alternate hosts for pathogens like cercospora, rust, or bacterial leaf spot, so be on the lookout for new problems while solving old problems. In the deep south, beans, yard-long (asparagus) beans, and cowpeas can succumb to heat, nematodes, rust, bacterial spots, and other pathogens and pests. Senna (tall) and Partridge pea can provide “chop-and-drop” organic matter as sunnhemp does. Sunn Hemp can host foliar pathogens (some possibly seed-borne), in Florida, and does not reliably form nitrogen-fixing nodules on the roots, even when inoculated. Even so, it is useful as a fast warm season green manure cover.
The flower Gaillardia (blanket flower) is a quick-to-compost, chop and drop option for late winter to late spring, It decomposes quickly, and can provide a quick green manure. Gaillardia is nematode-resistant, great for beneficials and pollinators, but is susceptible to some foliar pathogens later in the season. You can sow Gaillardia in August, or even later in fall for early spring flowering.
Due to climate change, and the more year-round activity of nematodes, pathogens, and pests in Florida, they’ve been including more nematode-resistant grasses into their rotations. We all need to be thinking more about warmer-climate options, as climate change continues to push pathogens and pests farther north, earlier each year.
If you have a hoophouse, you may now be planning or planting crops for fall, winter and spring. If you don’t have a hoophouse, this is a good time of year to consider getting one. See Twenty Benefits of Having a Hoophouse at the end of that post. There are grants available from NRCS, including reparation levels of funding from traditionally underserved groups of people. There are now companies that will construct your hoophouse for you, if you don’t want to do it yourself, or can’t. If you do want to build your own, there are detailed instructions in my book The Year-Round Hoophouse. You can buy the book here on my Books page direct from me, or from my publisher New Society, or you can buy it wherever books are sold.
I have many posts about winter hoophouse vegetables, so rather than try to write something completely new on the topic, I am going to give you a guide to find your way around the information already here.
See my recent post for info about fall broccoli and cabbage. Here I provide some more information and discuss other brassicas you could grow in the fall.
Temperature and Timing for Fall Brassicas
Germination: Brassica seeds will germinate at soil temperatures from 41°F (5°C) to 95°F (35°C). 41°F (5°C) can take 45 days for some brassicas, but in summer and fall, this isn’t the end of the thermometer we worry about! In summer and fall, soil temperatures are enough to germinate brassicas in 3-10 days. Optimum soil temperatures for germination are
77°F (25°C) for most Asian greens, broccoli, Brussels sprouts, cauliflower, collards, kohlrabi, pak choy;
86°F (30°C) for cabbage, including Napa cabbage, kale, turnips and rutabagas;
68°F (20°C) for mustard greens, and perhaps arugula (which might do better even cooler)
Cold-Hardiness: Consult this list of winter kill (air) temperatures for brassicas, for the crops you are growing.
32°F (0°C): some cauliflower curds, some pak choy
27°F (-3°C): many cabbage varieties
22°F (-6°C): some varieties of arugula
20°F (-7°C): broccoli heads (maybe OK to 15°F (-9.5°C)), some Brussels sprouts, some cabbages (the insides may still be good even if the outer leaves are damaged), some cauliflower varieties, some collards (Georgia Cabbage Collards, variegated collards), some mustards/Asian greens (Tendergreen), radishes (Cherry Belle), most turnips (Noir d’Hiver is the most cold-tolerant variety).
15°F (-9.5°C): some broccoli and cauliflower leaves, some cabbage (Kaitlin, Tribute), Red Russian and White Russian kales, kohlrabi, rutabagas (American Purple Top Yellow, Laurentian), most covered turnips, winter cress.
12°F (-11°C): some broccoli perhaps, some Brussels sprouts, some cabbage (January King, Savoy types), most collards, Koji greens, covered rutabagas
10°F (-12°C): Purple Sprouting broccoli for spring harvest, a few cabbages (Deadon), some collards (Morris Heading can survive at least one night), Belle Isle upland cress, probably Komatsuna, Chinese Thick-Stem Mustard may survive down to 6°F (-14°C), covered winter radish (Daikon, China Rose, Shunkyo Semi-Long survive), Senposai leaves (the core of the plant may survive 8°F/-13°C), Tatsoi, Yukina Savoy.
5°F (-15°C): some kale (Winterbor, Westland Winter), many of the Even’ Star Ice Bred greens varieties and the Ice-Bred White Egg turnip are hardy down to 6°F (-14°C)
0°F (-18°C): some collards (Blue Max, Winner, McCormack’s Green Glaze), Even’ Star Ice-Bred Smooth Leaf kale
-5°F (-19°C): Leaves of overwintering varieties of cauliflower, Vates kale survives although some leaves may be too damaged to use. Lacinato Rainbow Mix kale may survive this temperature.
Your Climate: Consult WeatherSpark. com to see when it begins to get too cold in your area. At our farm, the average daily low temperature on November 30 is 36°F (2°C). Decide your ideal harvest date for each crop. Although kohlrabi can take 15°F (-9.5°C), I’d want to get it all harvested by November 30.
Days to Maturity: Next factor in the number of days a crop takes to reach maturity. Work back from your desired harvest date, subtracting the number of days from sowing to maturity (or from sowing to transplant, plus from transplant to maturity). Work back another two weeks for the slowing rate of growth in fall. And perhaps work back another two weeks in case in gets colder earlier than usual. This provides your sowing date.
Mid-Winter Harvests: For crops that survive your winter, are you sowing to harvest in the fall, during the winter, or only in early spring? Brassicas for early spring harvest only can be sown in September or October in our climate. For those to be harvested during the winter, you need to have big enough plants going into the winter, to provide sustainable harvests (once a week in November and February and more in spring, plus maybe once a month in December and January)
Various Fall Brassica Crops
In the summer we try to have a No Visible Brassicas Month to break the lifecycle of the harlequin bugs. Once our spring kale is finished, the spring cabbage gathered in, and the spring broccoli mowed down, the only brassicas are seedlings hidden under insect netting. Our hope is to starve out the harlequin bugs or at least deter them from making too many more.
We sow other fall outdoor brassicas a bit later than cabbage and broccoli. These get transplanted from our netting-covered nursery seedbeds, to our raised bed area which is more accessible for winter harvesting and more suited to small quantities.
Outdoors we grow Senposai, Napa Chinese cabbage and Yukina Savoy. We have also sometimes grown tatsoi and komatsuna. Note that senposai grows quite large – give it similar spacing to collards.
We sow Asian greens for outdoors in the last week of June and first week of July, aiming to eat them before we start harvesting the ones in the hoophouse, which feed us all winter. We use Asian greens outdoors as quick-growing greens to fill the gap before our main fall greens (spinach, kale, collards, cabbage, broccoli) are ready to harvest. We don’t grow a lot outdoors.
If you don’t have a hoophouse, you can sow for outdoors later into the fall than we do, to get a longer harvest season than you otherwise would. And you certainly can direct seed them.
We sow collards in the first two weeks of July and transplant the bare-root transplants from the nursery bed when they are 3-4 weeks old. We plant at 18” (46 cm) in the row, with rows 12” (30 cm) apart. (if you grow a large kale, you might want similar spacing. Our Vates kale is small)
are rather a challenge in our climate, and not worthwhile. We have worked on finding the best variety (Oliver) and timing for our situation. Harvest timing is critical, as Brussels sprouts will not overwinter here.
are a tricky crop for us too. Be sure to check the “days to harvest” for each variety (they vary widely) and sow at a realistic date to get a crop before too many frosts endanger the curds. The number of days quoted for fall varieties of cauliflower already allows for the expected rate of growth at that time of year, so the 14 days for slower growth isn’t a factor. However, cauliflower is more tender, so allow for the possibility of a fall frost earlier than average.
We sow Vienna kohlrabi mid-July and transplant early August at 8” (20 cm) apart in the row, with 9-10” (23-25 cm) between rows. Later sowings (up till early September) would also work for the fast maturing varieties. Superschmelz Kohlrabi (60 days from transplanting) can also be summer sown for fall harvest. It produces 8-10” (20-25 cm) bulbs, which remain tender and an attractive globe shape.
We direct-sow two neighboring beds of kale on each of 8/4, 8/10, 8/16 and then carefully thin them, leaving one plant every 12” (30 cm). These plants grow quicker than transplants, as they have no transplant shock. Meanwhile, if we have gaps, we use the carefully dug thinnings from those beds to fill them. We want a lot of kale, and there isn’t time to transplant it all. Dividing up the sowings lets us focus on watering just one pair of beds at a time. Vates kale is the hardiest variety we have found, although I’d love to find a taller Scotch curled variety that could survive our winters (Winterbor does not survive as well as Vates).
Radishes, rutabagas and turnips are also brassicas, but I won’t say more here. look in the further resources.
Brassicas started in hot conditions do not usually bolt if they have enough water.
Protect seedlings and the new transplants with insect netting if you have brassica leaf pests (most of do!) You can remove the netting when the transplants are well established, or leave it on.
Use shadecloth to keep greens cool in hot weather, or plant them in the shade of other plants.
To keep crops in good condition later into the winter, use rowcover. I recommend thick Typar 1.25oz rowcover, which provides 6F degrees of cold protection. I wouldn’t spend the money on anything thinner, it’s too frustrating! We do not normally use rowcover in the winter for kale and collards, as they will survive without. In harsh winters we lose the collards.
Cultivation is a simple matter of hoeing, weeding, watering as needed, and watching for pests.
We’re solidly in the darker and colder half the year for our monthly series of 14 Workhorse Crops (asparagus, beans, cabbage, carrots, chard, collards/kale, garlic, potatoes, sweet corn, sweet potatoes, tomatoes, watermelons, winter squash, zucchini/summer squash). These crops are reliable and productive under a range of conditions. You can use the search box to find previous month’s entries, such as December.
Winter is a natural opportunity to reconsider the size of your garden, which crops to grow, and your growing methods. Perhaps this will be your first gardening year? If so, welcome! Use the search box to find specific info, or click the blog category to find some further reading. Hopefully, we all have our garden plans made and our seeds ordered. Maybe we are already looking at a planting schedule.
Workhorse Crops to Plant in January
In January, we can plant small small potato onions outdoors. We prepare the bed in the late fall and mulch it with hay, to plant in January. We rake off the mulch, plant the onion bulbs and then lay the mulch back on the bed, to control weeds and somewhat to insulate the little onion bulbs. These smallest potato onions are very cold-hardy, and will grow up to produce a single 3” (7.5 cm) large onion. A few will grow and subdivide to produce more small onions. Click the link to read the details.
Indoor sowings for later transplanting outside or in the hoophouse
In our greenhouse we fire up our germinator cabinets and sow our first lettuce and early cabbage (Early Jersey Wakefield and Faroa) and scallions in mid-January. The following week we sow our tomatoes to plant out in the hoophouse, and at the end of the month, spinach if we have not got enough sown in our hoophouse to transplant as bare-root transplants.
Hoophouse workhorse crops to plant in January
In the hoophouse we are sowing a second or third round of crops, mostly successions of greens and radishes. We have already pulled our first and second radishes, and some of the Asian greens.
This March we will be using a half-bed in the hoophouse for some early green bush beans. Like our other warm weather crops, these can be planted in the hoophouse a month earlier than outdoors. Two cautions with green beans in the hoophouse: buy a very upright variety, as the plants will be more sprawling than they are outdoors. Outdoors we grow Provider and Bush Blue Lake (both very reliable and productive), and in the hoophouse we like Strike. The second bean caution is that we have found the edge beds too cold for beans when we need to sow them, in March. Don’t plant them now, but order seeds of an upright variety and plan a non-edge bed. I’ll say more in March.
We have also planned our next round of early warm-weather crops, which we will transplant in late March and early April. Tomatoes and zucchini/summer squash are on our Workhorse list
We stop filling gaps in most of the Asian greens at the end of December, because they will start to bolt in January and/or because they are mature and we will be clearing the space to sow something else. Tatsoi, Tokyo Bekana, Pac Choi, Chinese Cabbage, Yukina Savoy, all need to be eaten during January. We sow spinach (the Racehorse Crop) in mid-January, to transplant in the hoophouse and outdoors.
On January 24 we sow Vates kale and Morris Heading collards in the ground in the hoophouse, in the space recently freed up by the Chinese cabbage. For 1080ft outdoors, we need 108ft of seedling rows. We can fit 14 rows of seedlings across a 4ft (1.2 m) bed.
We still have workhorse crops to harvest outdoors: chard, kale and collards, and perhaps cabbages. We’re down to three of our 14 workhorse crops to harvest outdoors in January, but we have the Racehorse Crop, spinach, too, and also luscious hoophouse greens.
Deadon (105d winter cabbage) is extremely cold hardy – we leave it outdoors until nights threaten to hit 10°F (-12°C), the lowest temperature I’ve seen it survive. We just had one night at that temperature, much colder than anything else so far this winter.
Chard can still be harvested outdoors if we covered it with hoops and rowcover. The outdoor killing temperature for unprotected Bright Lights chard is 22°F (–6°C); red chard survives down to 15°F (–9.5°C) and green chard to 10°F (–12°C). We have succeeded in keeping chard alive outdoors right through the winter, if we cover it.
Collards and Kale can be lightly harvested in January. Our mnemonic for sustainable harvesting of leafy greens is “8 for later”, meaning we leave at least eight inner leaves when harvesting the outer ones, to ensure the plants have enough strength to regrow. In October, November, February and March, we can harvest leaves from these plants once a week. In December and January, once each month is more like what we can hope for. Chard and senposai do OK with only 6 leaves left.
Hoophouse Workhorse harvests in January
We are harvesting leaves from our hoophouse Bright Lights chard at an adolescent size, cutting them into ribbons, and chopping the colorful stems, for salad mixes. Later, when the days lengthen, we’ll be able to harvest leaves for cooking.
The Red Russian and White Russian kales are ready to harvest now (we were a bit late with getting a successful sowing in September). Russian kales belong to the napus group of kales, which are better able to make growth in low light levels than oleracea types like the Vates we grow outdoors. Vates is our star outdoors, because it is more cold-hardy than any other kale I’ve found. The Russian kales have a tendency to wilt after harvesting, so we move fast and stand the leaves up in the buckets. We add some water to the buckets before rushing them to the walk-in cooler. (We do this with chard, turnip greens and Tokyo bekana too.)
The hoophouse senposai is on its third round of harvests, just two weeks after the second, which was one week after the first. This clearly demonstrated the slower rate of growth as temperatures and daylight decrease. The short days do cause plant growth to slow down, but this is not the only factor. Soil temperature is another. In our hoophouse, the soil temperature is still 50F (10C) in early January.
But hey! The length of daylight is now increasing! On the shortest day, December 21, we have 9 hours and 34 minutes of daylight, from 7.21 am to 4.55 pm. The mornings continue to get darker by a few minutes, taking a month to get back to 7.21, from a latest of 7.25 am. Meanwhile the evenings are getting lighter, gaining us 6 minutes by January 5. I’m typing this on my laptop onto a USB stick, as we are in day 3 of a power outage. I appreciate the lighter evenings! By January 21 we will be up to 10 hours of daylight!
Workhorse Crops from storage in January
Storage crops come into their own in December and January, once outdoor growth has slowed down. The flavor of stored sweet potatoes reaches its peak in late January! Besides the Workhorse Crops of carrots, potatoes, sweet potatoes, winter squash and garlic, there are many other root crops. See my posts Root Crops for the Month. Use hardneck garlic first, as it stores for only for 4-6 months. Softneck garlic can store for up to 7 months.
Eat up your acorn and other pepo types of winter squash, as they store for only 1-4 months. Maximas such as Cha Cha, Jarrahdale and Kabochas store for 3-5 months; Moschatas such as Butternuts and Cheese pumpkins will store for 8 months or even more. Seminole pumpkin can easily store for a whole year at room temperature. They do have hard shells and need a hefty cleaver to cut them open.
Our white potatoes are keeping well in the root cellar down at 40F-50F (5C-10C). We air it about once a week. We open the door on mild nights or chilly overcast days, depending what we get and what we need. Potatoes in storage after their first month are no longer respiring much at all. They should be dormant, and not in need of many air changes.
Our sweet potatoes are very delicious. We are eating about 40-50lbs (19-23 kilos) a week.
Stored cabbage can also be a boon, and this is also a good time to explore all the pickles and canned and frozen produce you put up earlier.
Workhorse Crops Special Topics for January: Making Schedules.
We continue our Garden Planning, ordering seeds and planning schedules of field planting and greenhouse seedling starting. In January we start sowing seeds indoors, and need our schedule figured out for that. We also need to pay attention to germination temps for various crops, so that we get them off to a good start, matched with crops needing similar temperatures in each germination cabinet.
Gardening does not end with the first frost! We will work our way from clearing the least hardy crops to those we can leave outside all winter. See our tableWinter Kill Temperatures of Cold-Hardy Vegetables. We will harvest or cover all the frost-tender crops, make a last harvest of rhubarb (the stems are hardy to 22°F (-6°C)) and hoop and rowcover the last outdoor lettuce. Our June-planted potatoes will be our last big harvest for the year.
We pull up the biggest Purple Top turnips and Cylindra beets, leaving the others a bit more room to size up before their killing temperature of 12°F (-11°C). Any day now, we’ll start harvesting fall leeks (King Richard and Lincoln), keeping the winter-hardy ones (Tadorna) for the winter.
I recommend learning your local weather patternsby keeping records and watching what happens. Here’s what I’ve learned about ours:
Our mid-Atlantic climate is controlled by three weather systems,
mainly by moisture from the Gulf of Mexico,
the Bermuda High Pressure area in summer,
and recurrent waves of cold Canadian air in winter.
Rain (statistically fairly evenly distributed throughout the year in our county) has slight peaks in January, February and March, and again in early June and August.
Some parts of our area can experience long periods of drought. September-November is the drier season but it’s also the hurricane season, so the net result is very variable.
We use Wunderground.combut subtract 5F° from their forecast night lows for our nearest town, and mentally downgrade the chance of rain by 10%, as rain often passes us by as it scoots along the river valley north of us.
Our average first frost date is October 14. Actually from our own records it has averaged 10/20 (13 years of our own records). So it’s time to start thinking about frost. It’s good to be prepared.
According to Dave’s Garden in Louisa County where I live, the threshold of 36°F (2°C) has a 50% likelihood on Oct 3; the 32°F (0°C) threshold has a 50% likelihood by Oct 13 and the 28°F (-2°C) threshold is as likely as unlikely by Oct 27. The 90% chances occur by Oct 14, Oct 28 and Nov 12 respectively.
Now that climate change is here, it pays to be ready for weather different from what we have experienced previously. Keeping records helps, as does having good thermometers for air and soil.
Four Ranges of Cold-Hardy Crops for Harvest at Various Stages of Winter
This simple model helps reduce confusion and set priorities
1. Crops to harvest before cold fall weather (32°-25°F) and store indoors:
Chicory for chicons or heads; crosnes/Chinese artichokes, dry beans, Chinese cabbage, peanuts, “White” Peruvian potatoes at 32°F (0°C) approximately, pumpkins, seed crops, sweet potatoes at 50°F (10°C), winter squash.
2. Crops to keep alive in the ground into winter to 22°-15°F (-6°C to -9°C), then harvest.
Store: Beets before 15-20°F (-9.5 to -7°C), cabbage, carrots before 12° F (-11°C), celeriac before 20°F (-7°C), kohlrabi before 15°F (-9.5°C), winter radish including daikon before 20°F (-7°C), rutabagas, turnips before 20°F (-7°C).
Use soon: Asian greens, broccoli, cabbage, chard, lettuce, radishes
3. Hardy crops to store in the ground and harvest during the winter.
In zone 7, such crops need to be hardy to 0°-10°F (-17.8°C to -12.3°C):Collards, horseradish, Jerusalem artichokes, kale, leeks, parsnips, scallions, spinach.
4. Overwinter crops for spring harvests before the main season.
In zone 7, they need to be hardy to 0°-10°F (-17.8°C to -12.3°C): Cabbage, carrots, chard, collards, garlic and garlic scallions, kale, multiplier onions (potato onions), scallions, spinach.
Frost is more likely at Twin Oaks if:
The date is after 10/14 (or before 4/30).
The daytime high temperature was less than 70°F (21°C).
The sky is clear.
The temperature at sunset is less than 50°F (10°C).
The dew point forecast is low, close to freezing. Frost is unlikely if the dew point is 43°F or more.
The Wunderground 3.30pm forecast low for Louisa Northside is 37°F (3°C) or less.
The soil is dry and cool.
The moon is full or new.
There is little or no breeze, although if temperatures are falling fast, the wind is from NW and the sky is clear, then polar air may be moving in, and we’ll get a hard freeze.
Frost Alert Card
For just this time of year, we keep a Frost Alert Card reminding us which crops to pay attention to if a frost threatens. We check the forecast online at 3.30 pm (we find that’s late enough to be fairly accurate about night temperatures and early enough to give us time to get vulnerable crops covered).
The big decision is the triage of harvest/cover/let go. Our list is not just crops that will die with the first frost but also ones that will soon need covering as temperatures decrease.
Cover lettuce, zucchini, summer squash, cucumbers, beans, Chinese cabbage, pak choy, lettuce and celery.
Harvest crops listed above that can’t or won’t be covered.
Harvest all ripe tomatoes, eggplant, corn, limas, cowpeas, okra, melons.
Harvest peppers facing the open sky, regardless of color. (Often only the top of the plant will get frosted).
Check winter squash and harvest any very exposed squash.
Set up sprinklers for the night, on tomatoes, peppers and a cluster of beds with high value crops.
We really like this pepper strategy we have developed: by picking just the peppers exposed to the sky, we reduce the immediate workload (and the immediate pile up of peppers in the cooler!) and we often get a couple of milder weeks after the first frost before the next. By then the top layer of leaves that got frosted the first time will have died and a whole new layer of peppers will be exposed and need harvesting. This way we get fewer peppers at once, and a higher percentage of ripe peppers, which have so much more flavor.
Our overhead sprinkler strategy is useful if a frost is coming early when we still have many tomatoes we’d like to vine-ripen. Keep the sprinkler running until the sun is shining on the plant sin the morning, or the sir temperature is above freezing again. The constant supply of water during the night does two things. First water gives off heat as it freezes. Yes, really. It’s easier to understand ice taking in heat to melt, but the flip side is that water gives off heat as it freezes. This latent heat of freezing helps warm the crops. And if ice does form, the shell of ice around the plants stops more cold damage happening.
Frost Alert List
Harvest all edible
Harvest all edible
Harvest all edible
Harvest all edible
Including green ones
Harvest all edible
Peppers exposed to the sky
Harvest all edible
West Indian gherkins
Harvest all edible
Harvest all edible
Harvest all edible
Beans #4, 5, 6, then cover
Uncover once mild again
Thick row cover
Spring hoops or none. Ditto
Thick row cover
Spring hoops or none. Ditto
Thick row cover
Double hoops – leave covered
Thick row cover
Last lettuce bed
Double hoops – leave covered
Overnight from before 32F till after sun shines on plants
Roma paste tomatoes and peppers
Other vulnerable raised bed crops
Cold Weather Crop Protection
Rowcover – thick 1.25 oz rowcover gives about 6F (3.3C) degrees of frost protection. Use hoops.
Low tunnels and Quick Hoops are wider version of using rowcover. They need the edges weighting down. Best for climates where the crops are being stored in the ground until spring, when they start growing again. Less useful in climates like ours which have very variable winter temperatures, and are warm enough that we realistically expect to harvest during the winter, not just before and after.
Caterpillar tunnels – 2 beds plus 1 path, tall enough to walk in. Rope holds cover in place, no sandbags.
High tunnels (= hoophouses), single or double layer. Double layer gives 8F (4.5C) degrees of protection, plus plants can survive 14F/8C colder than they can outside, without extra rowcover; at least21F/12C colder than outside with thick rowcover. Leafy crops are not weather-beaten. We strongly believe in two layers of plastic and no inner tunnels (rowcovers) unless the night will be 8°F (-13°C) or colder outdoors.
Salad greens in a hoophouse in zone 7 can survive nights with outdoor lows of 14°F (-10°C). A test year: Lettuce, Mizuna, Turnips, Russian kales, Senposai, Tyee spinach, Tatsoi, Yukina Savoy survived a hoophouse temperature of 10.4°F (-12°C) without rowcover, -2.2°F (-19°C) with. Brite Lights chard got frozen leaf stems.
I’m back again with my series of 14 Workhorse Crops (including two pairs) to focus on monthly until April 2022: These are crops that we can rely on under a wide range of conditions. Some Workhorse Crops are easy to grow, some pump out lots of food, some are “insurance crops”, some are especially profitable (for those growing for market), and watermelons are more of a circus pony than a workhorse!
I hope this series will help you become more efficient, productive and profitable (if selling) as your lives resettle. Maybe you are not at home as much as last year, but you’ve learned to deeply appreciate growing your own food. So you need to choose less time-consuming crops and growing methods. You can use the search box to find previous month’s entries, such as July.
Workhorse Crops to Plant in August
In August here in central Virginia, the heat is still oppressive, but the day-length is definitely getting shorter. We and our crops have a longer night in which to recover for the next hot day. I remember the year I realized we just had to do some of our broccoli transplanting in the late afternoons, because the evenings no longer held enough daylight! Since those days we have reduced the size of our fall broccoli planting!
This month we will really need to plan for our fall and winter garden and execute our plan. There’s no making up for lost time in the fall! As the days get shorter and the temperatures (thankfully) start to drop, plants take longer to mature. A delay of a day or two in sowing leads to a delay of a week or two (or more) in the start of the harvest. Keep records and try several dates, especially if this is your first year, so you can fine tune your plan next year.
In August we can plant 8 of our 14 Workhorse crops in central Virginia.
Beans, zucchini and summer squash
These warm-weather crops get their absolute last chance before the season gets too cold. We sow our last bush green beans 8/1-8/3, and zucchini, summer squash and cucumbers by 8/5 at the latest. If you are in a colder climate than ours, with a first frost earlier than our October 14 average, your last sowings of beans, zucchini, summer squash and cucumbers were in July. It’s too late for us to sow edamame or sweet corn. More on Last Chance Sowings in the Special Topic at the end.
We also reach our Last Chance for carrots for the year. We usually make a huge sowing of carrots on August 4, as our storage crop for the winter. We need 1500 pounds of carrots to feed us through the whole winter (30 bags). We sow 4000 row feet (1220 m), usually on temporary beds where we grew garlic until June, followed by a round or two of buckwheat cover crop before preparing the beds for the carrots. It really pays with carrots to reduce the weed level. We mulch our garlic and weed it every month from February until we remove the mulch when we see scapes in mid-May. Few weeds grow in the three weeks before we harvest. Buckwheat is a fast growing summer cover crop that is a modest size and easy to manage. It flowers about 4 weeks after sowing, and the flowers attract many beneficial insects.
After sowing the carrots with our trusty EarthWay seeder, we keep the soil damp by nightly watering until we see the red hooped stems of our indicator beet seedlings emerging. Then we know it’s time to flameweed. It’s usually the fourth day after sowing the carrots. This dispatches any new weeds thinking of emerging. As soon as we can see well enough to do so, we hoe between the rows with our scuffle hoes (stirrup hoes). Once the carrots are 1” (2.5 cm) tall, we hand weed, cultivate with claws (to kill weeds that haven’t even emerged yet) and thin to 1” (2.5 cm). Later we thin to 3” (7.5 cm) and weed again. That’s a September task.
Cabbage and Collards:
For the cool weather greens we are in our second season for the year. August is too late for us to start broccoli, collards or cabbage. In July and August we transplant the starts we sowed in June and July. At this time of year, we aim to transplant brassicas at four true leaves (3-4 weeks after sowing). In hot weather, use younger transplants than you would in spring, because larger plants wilt from high transpiration losses. If we find ourselves transplanting bigger plants, we remove a couple of the older leaves to reduce these losses.
To avoid flea beetles and harlequin bugs, we cover the nursery seedbeds until we transplant, and then cover the transplants for four weeks, until the plants are big enough to survive bug bites. Nets are better than rowcover in hot weather, as airflow is better and heating is less. This might require a bit of re-planning to get best value from the netting. For example – instead of planting the rows an equal distance apart, plant two rows closer than before, and then have wider aisles. One width of netting can cover two rows of brassicas, each with their own (offset) hoops.
Dubois Agrinovation has a range of ProtekNet Insect Exclusion Netting, made of clear high-density knitted polyamide (lighter weights), polypropylene/olefin (mid-weight) or polyethylene (heavy weights), with UV resistance. Be sure to buy the size mesh that keeps out the pest you are guarding against. See the Dimensions and Specifications tab on their website. We have bought the 0.0335″ x 0.0335″ (0.85 mm x 0.85 mm) mesh (against harlequin bugs) and the 0.0138″ x 0.0138″ (0.35 mm x 0.35 mm) mesh against flea beetles. Pieces can be sewn together, or Dubois will join them with zippers. See the Details tab for the insects excluded by each particular mesh. Light transmission is 88-93%. Ours have lasted many years, longer than rowcover. Use hoops to hold the mesh above the plants so insects can’t lay eggs through the holes. Purple Mountain Organics sell the whole range in full rolls, and the 25 g in 6.9’ x 33’. Johnny’s Seeds sells 6.9’ x 328’ 25 g “Thrips Net”. Compare shipping charges as well as netting price.
Two weeks after transplanting, we till or wheelhoe between the rows and hoe around the plants, removing the minimum amount of netting at any one time that we have to. Four weeks after transplanting, we remove the netting entirely, and hoe and till again. This time we undersow with a mix of clovers to be a long-term cover crop.
We sow 6 beds of kale, two every 6 days, (8/4, 8/10, 8/16, and if we need to resow, 8/24) until we succeed in getting enough established. We focus our attention on the two newly sown beds, watering daily as needed, until the seedlings emerge.
We want a lot of kale, and there isn’t time to transplant it all. We grow Vates dwarf Scotch curled, the most cold-hardy variety I’ve found. It isn’t huge – we plant 4 rows per bed 10″ (25 cm) apart. We’re looking at 6x4x90 plants.
We carefully thin, leaving one plant every foot (30 cm). Often we’ll get patchy emergence and we use the carefully dug thinnings to fill gaps and to plant other beds, at the same plant spacing. Our mixed direct-sow/transplant method allows for the fact of patchy germination, and requires less watering than if direct sowing it all at once. If your climate is a colder zone than ours, you would start sowing kale in July. We cover the beds with Proteknet.
Kale make some growth whenever the temperature is above about 40°F (5°C), which happens in our winters on many days, making this a valuable winter crop.
Chard: Swiss chard can be sown here in July or August, for a good fall harvest, with the option of overwintering under rowcover. It grows small leaves after only 35 days, and full-size leaves after 50 days. Chard is not eaten by flea beetles, and does not have problems germinating in hot weather like spinach does. Chard is our poster-child insurance crop! So easy! So productive!
Workhorse Crops to Harvest in August
Eleven of our 14 workhorse crops can be harvested in August!
Beans can be harvested here from late June until the first frost (or later if we cover the beds with rowcover when a frost threatens).
Cabbage planted in the spring is ready here from late May until mid-July, or a little later if we planted late-maturing varieties. When I was a new gardener I thought “early varieties” were to be planted early, and “late varieties” to be planted later. It would be clearer if they were labeled “fast” and “slow”! For the second half of the year, late varieties need to be sown earlier than early varieties to get a harvestable crop before it gets too cold. Be sure to check and compare the days to maturity numbers for the varieties you are growing.
We store enough spring cabbage to feed us until we start harvesting fall cabbage. It’s about a 50lb (25 k) bag a week. Fall planted cabbage won’t be ready until September 25.
Carrots: After May we hope not to need to sow more carrots until the beginning of August, because carrots grown in hot weather don’t taste sweet and can even be soapy. But home-grown hot weather carrots are still better than industrial carrots from thousands of miles away. This year we finished harvesting our spring carrots in July and stored them in the walk-in cooler.
If we have not grown enough carrots in the spring, we sow in June, or July if we must. When we do sow in June and July, those carrots are ready about 2-3 months after sowing (less time in warm weather, longer as the weather starts to cool in the fall)
Chard can be harvested whenever you want some. Just snap or cut off some outer leaves and stand them in a bucket with a little water (or if your cooler isn’t as big as ours, put them in a loose plastic bag in your fridge) until you cook them. For sustainable harvesting levels, we use our standard leafy green mnemonic “8 for later” meaning that we make sure to leave at least eight of the inner leaves on each plant, as we harvest the outer leaves. With chard, we can take a couple more than this, but we don’t want to exhaust our workhorses!
Chard is biennial, and will not bolt the first year (unless stressed by lack of water). Red chards bolt more easily than the green ones, presumably red crops are a bit stressed already, as they are short of chlorophyll, compared to the green ones, making photosynthesis harder work.
To overwinter chard in our climate, we cover the bed with rowcover on hoops. We can continue to make harvests into early winter. The mulch and rowcover help keep warmth in the soil, which keeps the crop growing.
The outdoor killing temperature for unprotected Bright Lights chard is 22°F (–6°C); red chard survives down to 15°F (–9.5°C) and green chard to 10°F (–12°C). If you want to overwinter chard in a climate colder than those temperatures, you can make a heavy harvest just before the weather turns seriously cold. This leaves the growing points of the plants alive. Cover the whole bed with thick straw or hay and wait for spring.
Potatoes, if planted in April would be harvested in August here. We can plant potatoes between mid-March and mid-June, leading to harvests in July-October. It’s as important not to leave potatoes baking in the sun as it is to protect them from frost, both when planting and when harvesting. Read more about potato harvest here.
Sweet Corn harvest is well underway. Usually we start sowing as early as possible and hope to start harvesting on 4th July. Sweet corn will be ready to harvest about three weeks after the first silks appear. This year we are later, but it’s just as delicious. We harvest 3 days a week, which gives us a nice amount from our 1050-1325 ft (320-400 m) plantings to feed our community. Some growers say you should harvest daily, but we find every other day is often enough. We are able to rush our sweet corn straight to the cooler, and it doesn’t have to travel after that, so we enjoy very fresh corn. Be sure to shade your corn after harvest and get it cooled as soon as possible, as the flavor deteriorates if it sits around.
Determining sweet corn maturity can be hard for new growers. Corn is ready when the silks become brown and dry. If the silks are not brown, just walk on by! If they are brown, and the ears are plump and filled to the end with kernels, take a closer look. Mature ears stand away from the stalks. This is called “flagging”. If you are still unsure, and don’t want to make too many mistakes, slit the husks at the side of the ear with your thumb nails and look at the kernels. (Don’t puncture the husks on the top of the ear as the dew and a million tiny beetles will get in and make a mess.) They should be a bit squarish and tight packed, not round and pearly with spaces between them. An opaque, milky juice will seep out of punctured kernels. If your sample ear wasn’t ready, push the husks closed over the cur and wait a few days.
Tomatoes are ripening fast outdoors now. Wait for the leaves to dry from rain or dew, before touching the plants, to minimize the spread of fungal diseases. Lightly press the bottom of the tomato to make sure it is soft enough to be fully ripe. Snap the tomato off at the knuckle, so that the plant gets the signal the fruit has gone, and will ripen more. We pop off the green calyx and set the tomatoes in plastic crates that fit two or three layers of fruit. It’s always tempting to include cracked ones, but they quickly turn nasty, so only do that if you are going to sort them promptly and process the damaged ones.
Watermelon harvest is starting. Determining ripeness is both art and science, and it’s worth getting good at it, as harvested watermelons don’t ripen further after harvest. An unripe watermelon is a sad waste.
The first step is to look at your sowing date and the days to maturity for the variety you’re growing. If it’s too soon for them to be ready, don’t tempt yourself by looking! If the dates are auspicious, the next step is to look at a big melon and find the curly little tendril that grows from the vine where the melon is attached (but on the opposite side of the vine). It must be brown and dry. If not, leave the melon untouched!
If it is brown, you can slap the melon and listen. The sound should be like thumping your chest, not your head or your belly! If that seems to indicate ripeness, we have one last check, that works for Crimson Sweet. I’m not completely sure it works for all varieties, although I think it should. Stand astride the melon, bend and put your flat hands, heel to heel, over the width of the melon. Pause and ensure silence (if you have coworkers) and then press down firmly with quite a bit of weight. If the melon is ripe, you will hear and feel a scrunch, as the ripe watermelon flesh splits inside the melon. Then you know you have a really good one. Rural legend says this test only works once, so don’t practice, just do it for real!
Cut the melon stem and gently lift and set the melon down in the cart, truck or at the side of the patch. I know some crews throw the melons from one person to another, but Crimson Sweets are too big, in my opinion.
Note that these rules apply to watermelons, not to any other type of melon.
Zucchini and summer squash in our climate need harvesting every day, if we are going to avoid blimps. Summer squash can be twisted off the plants, but zucchini need to be cut. The hairs on the leaves, combined with sweat, can cause unpleasant itchiness. Wear long sleeves or make special sleeves for this job that are not attached to any particular shirt. Make a casing and insert elastic around the top edge (and the bottom, if there are no cuffs). These sleeves can be bought, but everyone probably has an old shirt and could make their own.
We harvest every day to the fall frost (or beyond if we remember to cover that last planting with rowcover on chilly nights.).
From storage: spring cabbage, carrots and potatoes.
Workhorse Crops Special Topics for August:
Formula to Calculate Last Planting Date for Warm Weather Crops
To calculate the last worthwhile sowing date for warm weather crops, add the number of days to maturity and the length of your desired harvest period, and subtract this number from your average first frost date. Using yellow squash as an example:
Number of days from seeding to harvest 50
Desired length of the harvest period 21
14 days to allow for the slowing rate of growth in the fall 14
14 days to allow for an early frost (but we have rowcover) 0
Days before the first frost = total of these = 85
Last date for sowing, with October 14 first frost date = July 21
But by throwing rowcover over the last planting during cold spells, we effectively extend the growing season by 2 weeks, and we can sow our last planting of squash on Aug 5.
Last Chance Sowings: Fast Fall Crops for When Time is Short
Some crops mature in 60 days or less. These are mostly greens and fast-growing root vegetables. They are useful to fill space and time before you plant winter cover crops.
Ready in 30–35 days:
arugula, frilly mustards, kale, radishes.
some Asian greens: Komatsuna, Maruba Santoh, mizuna, Tokyo Bekana.
beets, Napa cabbage, small cabbages (Farao or Early Jersey Wakefield), collards, kohlrabi, pak choy, turnips
Use the chart below to figure out your last chance to sow crops with various days to maturity
Sowing dates for fall crops with various days to maturity
For example, Early Purple Vienna Kohlrabi takes only 60 days from sowing to harvest in spring. Allow for the slowing rate of growth in fall (unless you will use rowcover). Kohlrabi is hardy to maybe 15°F (-9.4°C). When is it likely to get that cold? Not before the beginning of November here, so counting back 31 days in October, plus 30 in September, plus 31 in August – that’s 92 days already, more than enough. We could sow kohlrabi in early August and get a crop at the end of October.
is available from Mother Earth News Fairs Online here.
The Food Independence Course Part Two consists of eight video presentations, most of which come with pdf handouts. My contribution is Growing Asian Greens, and pairs nicely with the Guide to Asian Vegetables by Wendy Kiang-Spray, author of The Chinese Kitchen Garden: Growing Techniques and Family Recipes from a Classic Cuisine. Other topics include Dandelion Wine, Homemade Teas, Food Conversations, Passive Solar Greenhouse Design, Productive Growing from Home, and Growing Your Own Spices.
Easy DIY Cabbage Butterfly Decoy!
The Good Seed Co blog posted this lovely idea for protecting brassicas from those white butterflies Pieris rapae. It’s based on the discovery that the butterfly is territorial. If it sees a slightly bigger competitor it flies away. I have not tested this system, but it sounds like an interesting and fun project that costs next to nothing.
We don’t have many cabbage butterflies because we have both a predator – the paper wasp, and a parasite – Cotesia glomerata, a parasitic wasp that lays its eggs in small (first instar) larvae of the Cabbage White Butterfly, or Imported Cabbage Worm (as we call it in the US). Cotesia larvae emerge from the caterpillars after 15-20 days and spin yellow or white cocoons on or near the host which dies when the wasps emerge. We often find clusters of these cocoons (about the size of cooked rice grains) on the underside of brassica leaves.
I learned from Bryan O’Hara in No-Till Intensive Vegetable Culture that our friends, the Cotesia glomerata wasps that parasitize brassica caterpillars, and overwinter as pupal cocoons on the undersides of brassica leaves, will hatch out in spring on the very day the overwintered brassicas start to flower. The 20-50 day lifecycle needs brassica flowers, so don’t be in a hurry to cut down all your bolting greens! The flowers provide nectar for the adult wasps. The leaves, as we know, provide food for the caterpillars, which provide the host for the wasps to lay eggs in. The wasp larvae feed on the caterpillar until it dies, then pupate.
There’s an incredible National Geographic video of this cycle, showing parasitic wasp larvae swimming around inside a caterpillar, bursting out through its skin. The weirdest bit is that it is the dying caterpillar that spins the protective cocoons around the pupating larvae. And us who plant the brassicas that feed the caterpillars! Who is the farmer and who is farmed?
Average frost dates – the last one in spring and the first one in the fall – are useful to know when planning your crops. Once you’ve calculated your planting out date for various crops, you can work back to set sowing dates for the crops you’ll transplant, and bed prep dates for every crop. You can also make a co-ordinated plan that paces the work and doesn’t have too much in any one week, or any while you plan to be on vacation. You can calculate your first sensible planting date for each crop, your last one and perhaps some in-between ones to keep up supplies throughout the season.
You can use your average first fall frost date to make sure you don’t plant frost-tender crops too late in the season when you have no hope of them maturing in time for a harvest. You can extrapolate beyond the frost date to figure out when to harvest the more hardy crops. See my Winter-Kill Temperatures chart for useful tips.
By looking at the number of frost-free days in your area you can see whether to grow long-season tender crops like watermelons, or whether it’s only worthwhile if you choose fast-maturing varieties.
The Harvest to Table website is a trove of clearly explained information.
Average frosts are only averages. Actual frosts can sometimes happen two weeks either side of those dates. Frosts are only one particular temperature, and may not matter to the crop you’re planning for. Soil temperatures for germination and for planting are another important part of planning.
K-State Extension has a brief article on the importance of measuring your soil temperature.
Harvest to Table also has a list, ranked by temperature, so you can see what you can plant this week.
Scottish Climate Friendly Farming Video
Farmer Patrick Barbour, from Highland Perthshire, has won the search for Scotland’s climate friendly farming champion. Patrick’s innovative three-minute video entry, filmed at Mains of Fincastle, near Pitlochry stunningly illustrates the benefits of tree planting, species rich grassland, rotational grazing for cattle and sheep and stitching nitrogen fixing crops into pastures. It is available to watch at: Next Generation Climate Change Competition
This is an updated version of the section I included last week, followed by the all-important section on how to stop or at least delay, plants from bolting.
Bolting is the term for plants going to seed. Rather than grow more leaves and bigger roots, the plants develop stems, fewer and skinnier leaves, then flowers and seeds. The plants are switching their energy to survival of the species in response to the conditions.
When a plant starts to bolt, it is usually a sign to expect a poor harvest. It is also an indication that the plant will decline in terms of flavor. Lettuces become bitter. As long as you can harvest leaves or roots that are not too woody, you can eat bolting plants. But they do become too tough and inedible at some point.
Although bolting is usually seen on crops approaching maturity, it is initiated much earlier, by plant hormones called gibberellins. Bolting then can be triggered by one or more factors, sometimes acting in concert.
·Increased day length: Bolting can happen (especially with annual crops) when day length increases as summer approaches. This can be a problem if you planted your seeds too late in the spring to get a harvest before the plants bolt.
·High soil temperatures: As soil temperatures increase in summer, annual plants are triggered to begin seed and flower production. This isn’t a problem late in the crop’s life, after bountiful harvests. But, when spring has unusually hot weather or if you plant crops too late into the growing season, your crop may bolt before any harvests. Cool weather crops like lettuce and spinach will bolt in spells of hot dry weather.
·Cold temperatures: A sudden cold snap in spring can signal to biennials (such as onions, leeks, beets and carrots) that “winter” has happened and it’s time to develop seeds for the next season. If you start these crops too early in the calendar year, you risk exposing young plants to cold weather, priming the plants to develop flower stems as soon as the weather warms up again.
·Plant size: larger plants are more likely than small ones to bolt when a trigger such as cold temperatures strikes.
·Annual plants (basil, lettuce, melons, peas) grow from seed, flower and set seed all in one year. That can be spring to winter or fall to summer. Annual crops are sensitive to daylength, and will start making flowers as the daylength (and temperature) increase. Many annuals are crops where we eat the fruit or seeds and bolting is not an issue.
·Biennial plants (beets, brassicas (broccoli, cabbage, kale, turnips etc), carrots, celery, chard, leeks, onions, spinach) grow big the first year, then seed the second year, if we still have them. Many biennial food crops are grown as cool weather annuals.Unsettled weather (cold nights, hot days, late frosts) early in the season can cause biennials to bolt. Bolting usually occurs after a prolonged cold spell, especially with immature plants. Brassicas started in cool conditions, and grown on in warmer conditions, are primed to bolt. Tatsoi, for example, bolts readily in these conditions.
·Root stress: Bolting caused by root stress typically happens when you disturb a plant’s root system by transplanting, or if your plant runs out of growing space in a container that’s too small, or because the rows did not get sufficiently thinned.
·Stresses such as insufficient minerals or water: Healthy soil with plenty of nutrients and balanced moisture levels will encourage quick growth. Every grower should aim for this balance, especially those in hotter climates where it’s a race to plant leafy salads, cooking greens and root crops before the hot weather wins. High salt levels are another stressor, particularly in hoophouses.
Avoiding or postponing bolting
·Investigate, record and follow local last planting dates for early spring crops, and first planting dates for fall crops.
·For some crops there are varieties that are resistant to bolting, such as ‘Boltardy’ beets. If you have had repeated trouble with a particular crop bolting, look for bolt-resistant varieties. Florence fennel is particularly prone to bolting so try ‘Amigo’, ‘Victorio’ and ‘Pronto’ varieties and sow in summer for fall harvests. White and brown onions are less prone to bolting than redvarieties.
·Onions grown from sets (plants stymied in mid-growth) are prone to bolting. Grow onions from seed or plant heat-treated sets in early spring (exposure to high temperatures suppresses flower-bud formation)
·Try to avoid stressing your plants.
·Direct sow. Plants prone to bolting due to root stress (beets, carrots, radishes, turnips, and many herbs) grow best when you direct sow them, rather than transplanting. This allows their root systems to develop without interruption.
·Transfer seedlings to a larger pot before the roots get crowded (“root bound”)
·Harden off plants before transplanting. Get them used to outdoor conditions, avoiding shock.
·Cover plants in the event of a cold spell, which can keep them from being directly exposed to cold temperatures, rain, or snow.
·Use seaweed or kelp liquid fertilizer, which help plants handle stress better.
·To postpone bolting in spring, avoid chilling young brassica plants (above 5-8 true leaves, or with a stem diameter above a certain size), below 40°F for a few days, or longer at 50°F (10°C). The interaction of plant size (age) and cold temperatures makes the plant flower. Older plants are more likely to bolt than young plants at the same cold temperature. Young hardened-off plants are very resistant to bolting. If broccoli and cauliflower plants are stressed into flowering while young, the small plants will only produce small heads.
·Coax your vegetables to maturity quickly and efficiently so they’re ready to eat before the plants have a chance to flower.
·Mulch spring crops early to help keep the soil and roots cooler, extending the harvest. We have found this to be especially helpful with spring cabbage and broccoli.
·Cover near-mature bulbing onions during cold spells to protect them from bolting.
·Use shadecloth to keep greens and lettuce cool as the season warms, or plant them in the shadeof other plants
·Consider the timing of sowing. Grow storage carrots and beets in the fall, not the spring.
·Many cool-season crops mature better before temperatures get to 80°F (27°C), so plan accordingly. If your springs usually heat up fast as ours do, start earlier, or plant in late summer, fall, or even winter, depending on your climate, and grow these crops in reliably cool weather.
·Plant later annuals after the summer solstice to grow in the decreasing daylength without risk of bolting (unless another factor such as stress or temperature comes into play).
·Once cold-hardy plants are big, they can endure cold winter temperatures. They will not bolt until the day length is lengthening again (after the Winter Solstice) and the temperature starts to rise.
·Brassica greens started in hot conditions do not usually bolt if they have enough water. I recommend both Tokyo bekana and Maruba Santoh (both “celery cabbage” types of Asian greens), for summer substitutes for lettuce. You do have to grow them fast, with plenty of water, and insect netting if you have brassica leaf pests.
·In central Virginia for outdoors in spring, the only Asian green we grow is senposai, which we have found to withstand bolting until a bit later than others. There may be other loose-leaf Asian greens we could grow, but spring can go from too cold to too hot very quickly here.
·To prevent bolting in Asian greens, sow these crops from July onwards. Asian greens bolt as nights become warmer – on average above 50-55°F (10-13°C)
·Winter radishes will only form a good root if they are planted in late summer or fall as the days get shorter.
·Sow quick-maturing plants like lettuce, cilantro, or radish regularly. Succession sowing can keep some plants always coming into maturity instead of relying on one sowing to last a long time without bolting in the garden.
·If you grow biennial plants and harvest them in the first year, they are unlikely to bolt. A few specimens may still do so. Chard is cold-sensitive, and by delaying sowing until April, we cangrow chard all summer as a fresh cooking green, and it will not bolt no matter how hot it gets. We cannot keep kale and collards producing all summer as gardeners in cooler climates do.
·For early harvests of biennials, start the plants in plug flats or soil blocks indoors, planting them out when the weather is more settled and avoiding cold stress.
·Dry soil can also encourage bolting, particularly with cabbages, cauliflower, arugula and spinach. To avoid this, provide ample water.
·If the compost is not nutritious enough, top-dress with more compost.
·For over-wintered leeks and onions, bolting can be delayed by topdressing with 2-3oz per sq yd (70-100g per sq m) of nitrogen rich fertilizer very early in the new year
·Pick off the outer leaves from leafy crops such as lettuce, keeping the plants from maturing. As well as providing you with multiple harvests, this can extend the harvest period by as much as 10 weeks, although in hot weather the flavor may still become bitter, even without bolting. Grow Batavian varieties in hot weather.
·With some crops, like basil, if you catch a plant in the very early stages of bolting, you can temporarily reverse the process by snipping off the flowers and flower buds. The plant will go back to producing leaves and will stop bolting. In most plants (such as broccoli and lettuce) this only buys you a little extra time to harvest the crop.
·Cabbage wrangling: If a cabbage is mature and preparing to split open (a stage of bolting) before you are ready to harvest, you can get a firm hold on the head and give it a quarter turn. This will break some of the feeder roots and reduce the water uptake, delaying splitting.
Some specific examples
Lettuce is one of the vegetables most frequently seen bolting. I’ve even seen photos of bolting lettuce in garden magazines, with no acknowledgement that the plants are only fit for the compost heap.
The bitter taste of bolting lettuce is caused by a rapid buildup of compounds called ‘sesquiterpene lactones’. Plants manufacture these compounds to provide resistance to leaf-eating insect pests. The plants also speed up their production of seeds to grow the next generation.
Onions (excerpted from Sustainable Market Farming)
Onions are a biennial plant. When onion plants experience an extended period of cooling temperatures, such as winter, they go dormant. When temperatures rise, they start growing again. After being exposed to cold temperatures, smaller seedlings with a diameter less than pencil thickness (3/8” or 1 cm), and fewer than six leaves will resume growth and not usually bolt. Over-large transplants are more likely to bolt. If seedlings are becoming thicker than a pencil before you can set them out, undercut 2″ (5 cm) below the surface to reduce the growth rate.
The trigger for the transition from bulbing to flowering is temperatures below 50°F (10°C) for 3-4 weeks, after the plants have six leaves or more. This can happen, if you are unlucky, after an unexpected cold period in spring. Avoid bolting because the bulbs start to disappear to feed the growing flower stems. Bolted onions will not dry down to have tight necks and so will not store.
It is possible in our climate (and perhaps yours) to sow onions in the fall and plant the seedlings out in the early spring, for bigger vegetative growth and therefore the chance of bigger bulbs. The temperature-and-size trigger limits how early in the fall seeds can be sown – if the seedlings have made lower stems larger than a pencil in diameter when winter closes in, the plants are likely to bloom in the spring rather than forming bulbs. A few onion plants will likely always bolt, especially if the spring is long with alternating warm and cool spells.
Starting seedlings in a hoophouse in early November works well for us. Previously we sowed outdoors in late September and protected the plants with row cover and cold frames, a system that would work fine somewhere warmer than zone 7. The hoophouse works well for us because the plants get much better air flow, are protected from very cold temperatures, and can be easily seen and cared for. The plants grow faster in the hoophouse than outdoors, so we must start them later. Outdoor sowings tend to suffer some winter killing and varying degrees of mold. The colder the temperatures the plants experience, the more likely it is for the larger ones to bolt before growing large bulbs. Hence a more moderate microclimate, such as a hoophouse, reduces the rate of bolting. In colder zones, a slightly heated greenhouse might work better for over-wintering.
Spinach grows best in temperatures from 35-75°F (1-23°C). Spinach will begin to flower once spring days are longer than 14 hours and temperatures get above 75°F (23°C). The leaves become pointed (arrowhead shape), less fleshy, and the plants get taller, and develop a flower head in warmer weather. Plant spinach 4-6 weeks before the average date of the last frost in your region. You can also sow 6-8 weeks before the first fall frost. You can also plant seed in a cold frame in fall or cover late season plants with rowcover, for harvests during the winter or the following early spring. In warm weather grow chard or leaf beet instead of spinach.
Change your attitude
You can’t control the climate, the weather or the daylength. If you’ve taken the steps listed above and your plants are still bolting, change your attitude!
As soon as you see signs of your greens bolting, harvest the entire plant. According to some excellent cooks, flowering bok choy stems are tender and sweet and make a great addition to stir-fry and salads.
Learn to appreciate peppery arugula or slightly bitter lettuce (mixed in with other salad greens). It can be more enjoyable than the bland tasting lettuce available in stores.
Bolted vegetables are food for pollinating insects such as bees. Enjoy the beauty of sprays of yellow brassica flowers, majestic globes of leeks and onions, and lacy carrot umbels.
As soon as the soil is dry enough and not frozen, we spread compost on the raised beds we plan to plant in February and March, and till in the compost. We make ourselves a Spring Start-up Plan, so we know where to focus our energy when the weather gives us a chance.
Spring Start-up Plan
We aim to spread compost 4-6 weeks before planting, rototill 2-4 weeks before planting, and prep the bed a week or two before. This is more time than we allow later in the year, but in early spring it’s good to seize the opportunities that arise and not take the weather for granted.
This means in January we compost and till beds for spinach, turnips and our first carrots. In the first half of February we till the turnip beds and any beds of winter-killed oats cover crops that we will be planting soon. We compost the first lettuce bed, the kale and collard beds, and those for cabbage, beets, more carrots, senposai and peas (all have planting dates March 9 to 15). In the second half of February, we compost the third carrot bed and till the ones we already composted. In early March we till the third carrot bed.
Once we get to March, day length has increased and temperatures are starting to climb. There is a noticeable increase in the rate of germination and growth (unlike for our February sowings, which are rooted in faith and optimism!) All being well with the weather (it’s extremely wet this year!), in early March, we direct sow turnips (3/6- 3/16), and radishes #1 (Cherry Belle or some other fast variety)
In mid-March, we can transplant kohlrabi. And we direct sow carrots #3 and beets. See below for more about beets. In late March, we direct sow our carrots #4, and more radishes and beets. We can sow kohlrabi if we have no transplants, and thin to 6” (15 cm) later.
We plant potatoes when the daffodils bloom, usually mid-March. Last year I wrote an extensive series of posts about growing potatoes.
Beets are workhorse root crops that thrive in mild weather, store well, and are popular traditional foods. They are crops that can provide high yields for the time invested.
Beets come in several types, round, top-shaped and long. The size and quality of the greens is a factor if you sell bunched beets with tops, or use the tops for greens. We like the 6” (15cm) long Cylindra/Formanova/Forono ones (55 days to maturity, OP). They are very tender and easy to cut into regular slices, for pickles or cooking. The skins come off easily, and the flavor is very sweet and the texture tender.
Among round ones we like Ace (50 days to maturity, F1 hybrid), and Detroit Dark Red (60d), a tender open-pollinated variety. Detroit Crimson Globe is said to maintain better flavor in hot weather than most others, which can develop off-flavors. Early Wonder Tall Top (48d), is also open-pollinated. Lutz Green Leaf (70d) is a big long-storage variety. There are also golden beets, white beets and candy-striped Chioggia beets, although in my experience, what they gain in appearance they lose in flavor and tenderness.
Beets seeds average 35,000 /lb. 2,200/oz, 80 seeds/gm. 1,285 seeds (2/3 oz, 18gm) sow 100’ (30m).150’/oz, 2,300’/lb., 9 lbs/acre. 315,000 seeds/acre. Yield can be 40 lbs. (18kg) greens, 100 lbs. (45kg) roots/100’ (30m), or 14,000 lbs/acre, 2540 kg/ha.
Beets need a pH of 6.0-7.0, preferring 6.5-6.8.They require abundant potassium, which can be supplied by woodash.Boron deficiency can show up in beets as internal browning, or dark dead tissue, as well as distorted leaf growth. It is most likely to occur in alkaline soils after long hot, dry spells. Beets can suffer from “zoning,” (white rings in the roots), if there are acute weather fluctuations.
Sow beets whenever the soil is between 50°F (10°C) and 95°F (35°C), so long as you can keep the surface damp. With beets we do a single sowing in mid-March and more in early August. We are growing for fresh use, pickling and storage, but not bunch sales, so we don’t need to do frequent sowings. For a continuous supply of greens and baby beets, sow every 2 weeks from spring until 8 weeks before regular frosts usually occur, or about 10 weeks before a heavy freeze is expected.
We direct sow either dry beet seed, or some we have presoaked for 1-2 hours. Beet seed drowns easily: don’t use too much water or soak for too long. Sow 0.5″(1.2cm) deep in spring, deeper in hot summers, but never more than an inch (2.5cm) deep. We sow an inch (2.5 cm) apart in single rows 8-10” (20-25cm) apart. Others sow in bands 2-4″ (5-10cm) wide, at about 15 seeds/ft (2cm apart), with bands 12-18″ (30-45cm) apart. As for carrots, avoid soil crusting.
It is important to get good soil contact for the corky seedballs, so tamp or roll the rows after seeding. Keep the rows damp, by watering as needed for the 5-17 days they take to emerge. Beet seeds are actually seed balls (clusters of seeds) so each one you plant will produce several seedlings right next to each other. “Singling” the beets is an important step, and they will benefit from hoeing, thinning and weeding. Beets deal with weed pressure and crowding a lot better than carrots do, so if you have to choose which to weed, the carrots win! We thin in stages, so that at the second thinning, the baby beets can be used as a crop.
For mature beets, allow each a minimum of 3” (7.5cm). The Cylindra beets can be left a bit closer, and will push themselves up out of the soil as they grow. Know and Grow Vegetables recommends establishing 5 plants per square foot (54 per square metre) for early beets. This translates to a final spacing of 4 x 7” (10 x 18cm). For maincrop beets, aim for 10-15 per square foot (107-161 per square metre.) For maximum total yields of small sized roots use a spacing of 1 x 12” (2.5 x 30cm).
This info about growing beets is excerpted from my book Sustainable Market Farming. See the book for more on pests and diseases, harvesting and storing, and seed saving.
See Root Crops in August for more about fall beets. Beets can be tricky to germinate in hot weather, but to get good storable-sized roots, we need to get them established by 8/20. (Two months before our average first frost.)
Root Crops to Harvest in Central Virginia in March
From storage, if we still have them, we can eat beets, carrots, celeriac, kohlrabi, parsnips, potatoes, rutabagas, sweet potatoes, and turnips.
As in January and February in central Virginia, there are no roots to harvest outdoors in March except parsnips, Jerusalem artichokes and horseradish. We do have horseradish, but not the others, but we don’t have a lot of demand for that.
We have had outdoor night temperatures of 12°F/-11°C and 11°F/-13°C. This winter we had some carrots outdoors over the winter. We harvested them and got 150 pounds from 400 row feet. Not a high yield but they do taste good! They are Danvers 126. The intended sowing date was August 14, but we didn’t get the seed in the ground until September 5.
In the hoophouse our #4 radishes will get harvested during March. Our #5 radishes, sown 12/23, will then feed us until around April 7.
We still have some of our good size second hoophouse turnips until mid-March. We sowed those on October 25. The greens are a bit ragged now and less appetizing for cooking, although on cold rainy days, they make for more pleasant harvesting than any greens outdoors! Turnip greens (and Russian kale) are our last hoophouse greens to bolt, so we value them.We need to harvest the turnips to make space to transplant our hoophouse tomatoes in mid-March.
Other Root Crop Tasks in Central Virginia in March
Special Root Crop Topic for March in Central Virginia: What makes vegetable crops bolt?
Bolting is the term for plants going to seed. Rather than grow more leaves and bigger roots, the plants develop stems, skinnier and fewer leaves, then flower buds, flowers and seeds.
The plants are switching their energy to survival of the species in the face of unsuitable conditions.
When a plant starts to bolt, it is usually a sign to expect a poor harvest. It is also an indication that the plant will decline in terms of flavor. Lettuce become bitter. As long as you can harvest leaves or roots that are not too woody, you can eat bolting plants. But they do become too tough and inedible at some point.
Crops inclined to bolt include arugula, basil, beets, brassicas (such as cabbage), carrots, celery, leeks, lettuce, onions, turnips and spinach.
Bolting is initiated by plant hormones called gibberellins.
Although bolting is usually seen on crops approaching maturity, it is initiated much earlier.
It’s a complex business, understanding the various triggers to bolting.
Stress factors, including changes in day length (usually an increase), high temperatures or low temperatures at particular stages in a plant’s growth cycle, plant size, plant type, root stress, and stresses such as insufficient water or minerals.
Increased day length: Bolting can happen when day length increases as summer approaches. This can be a problem if you planted your seeds too late in the spring. The extra hours of light trigger annual plants to run to seed.
High soil temperatures: As soil temperatures increase in summer, plants are triggered to begin seed and flower production. This isn’t a problem late in the crop’s life, after bountiful harvests. But, when spring has unusually hot weather or if you plant crops too late into the growing season, your crop may bolt before any harvests. Cool weather crops like lettuce and spinach will bolt in spells of hot dry weather.
Cold temperatures: A sudden cold snap in spring can signal to biennials (such as onions, leeks, beets and carrots) that “winter” has happened and it’s time to develop seeds for the next season. If you start these crops too early in the calendar year, you risk exposing young plants to cold weather, priming the plants to develop flower stems as soon as the weather warms up again.
Annual plants grow from seed, flower and set seed all in one year. That can be spring to winter or fall to summer. Annual crops are sensitive to daylength, and will start making flowers as the daylength (and temperature) increase. When an annual plant bolts, it’s the beginning of the end.
Biennial plants (onions, leeks, carrots, beets, and chard) grow big the first year, then seed the second year. They can initiate flowers in the first yea, due to unsettled weather early in the season. Bolting usually occurs after a prolonged cold spell, often during an immature stage. Cold nights, hot days and late frosts may also contribute to premature flowering.
Root stress: Bolting caused by root stress typically happens when you disturb a plant’s root system by transplanting, or if your plant runs out of growing space in a container that’s too small.
Stresses such as insufficient minerals or water: Healthy soil with plenty of nutrients and balanced moisture levels will encourage quick growth. Every grower should aim for this balance, especially those in hotter climates where it’s a race to plant leafy salads, cooking greens and root crops before the hot weather fights against you.
Collards bolting in late March.
Photo Pam Dawling
Next week I will provide information on avoiding, preventing and postponing bolting.
When I check to see which blog posts are gathering interest, the ones featuring Tokyo bekana are doing well this past year. You might wonder why. It’s because it’s one of the greens being grown on the International Space Station, and most people haven’t heard of it before. I’ve written about Tokyo bekana as a winter hoophouse greenhere on earth, and as a summer alternative to lettuce in places with hot summers (Virginia, Jamaica, Cuba).
According to an article in The Atlantic, the first plant to grow in space was thale cress, Arabidopsis thaliana, a spindly plant with white flowers, related to mustards, mature 6 weeks after sowing. This was in 1982, on board Salyut, a Russian space station of the era. Thale cress was chosen for practical reasons: a fairly quick life cycle that allows for many analyses in a short time.
The first vegetable grown and eaten on the International Space Station space was Outredgeous red romaine lettuce, in 2015. Bred by Frank Morton ofWild Garden Seed. 64 days to maturity on earth, 33 days in space, with intensely dark red, slightly ruffled leaves forming loose upright heads. “We are an organic seed farm in the Pacific Northwest, established in 1994, owned and operated by Frank and Karen Morton. We are known for farm-original varieties of many salad greens, vegetables, herbs, and flowers.” This is an Open Source Seed Initiative variety. The OSSI pledge: “You have the freedom to use these OSSI-Pledged seeds in any way you choose. In return, you pledge not to restrict others’ use of these seeds or their derivatives by patents or other means, and to include this pledge with any transfer of these seeds or their derivatives.” Read more about OSSI here!
Space gardening has to be hydroponic – there is no soil involved. I am a big proponent of “Keep the Soil in Organic”, as I believe there are nutrients we don’t yet know about, that the plants take up from the soil in the proportions they need. But in space, you can’t do that, soil is way too heavy. If you watched The Martian movie, you saw some hilarious efforts to grow potatoes in “soil”.
In the Space Station is a plant growth system Veg-0, fondly called “Veggie,” a chamber about the size of a carry-on piece of luggage, typically holding six plants. The magenta light bathing the plants in Veggie is the result of a combination of red and blue LED lights. the most efficient way to get good plant growth. Green LEDS were added later so the plants look like edible food rather than strange decorations. Without gravity, plants use other environmental factors, such as light, to orient their growth.
To grow the first food crop, a root mat and six plant “pillows,” each containing ‘Outredgeous’ red romaine lettuce seeds, were put into Veggie. Inside each plant pillow is a growth medium including controlled-release fertilizer and calcined clay as used on baseball fields. This clay increases aeration and helps the plants grow. The plants get about 100 milliliters of water each to start the seeds growing. The pillows distribute water, nutrients and air around the plant root, to prevent the roots from drowning in water or being trapped in air (because of the way fluids in space tend to form bubbles).
Veggie remains on the station permanently as a research platform for other leafy plant experiments (and a source of food and psychological comfort!). The crew does get some fresh fruits and vegetables when a supply ship arrives at the space station, but the quantity is limited and they are soon gone.
Tokyo bekana was chosen for its fairly short stature and fast growth. Other contenders included Swiss chard, spinach and beets. The scientists who noted Tokyo bekana’s short stature haven’t seen the healthy 24” (60 cm) ones I just pulled up in our hoophouse today! In our hoophouse climate, it bolts in January, so our plan includes clearing the crop then and sowing spinach for bare-root transplants.
“We conducted a survey of several leafy green vegetables and looked at how the crops grew, how nutritious they were, and how a taste panel felt about them,” Gioia Massa, a scientist on the project, told Modern Farmer in an email. “The ‘Tokyo bekana’ Chinese cabbage variety was rated as the top in growth and the favorite of tasters.”
In some reports the little known Tokyo bekana is called, rather generally, but confusingly, Chinese cabbage or, more specifically, but mistakenly, bok choy, but we growers know the difference! Different sources in English use different names for Asian vegetables. I have a series of blogposts Asian Greens for the Month, which you can find by clicking that Category or using the search box.
2. The cabbage family, Brassica oleracea, of European origin (Kai-lan, Chinese kale)
3. The Chinese Mustard family, Brassica juncea (Ruby Streaks, Golden Frills, Red Rain)
Returning to 1a Brassica rapa var. pekinensis, there are two types: Wong Bok (Napa cabbage such as Blues, and cylindrical Michihli types) and Celery cabbage (pe tsai), which includes Tokyo bekana and the very similar Maruba Santoh.
A fast-growing, looseleaf, non-heading vegetable with light green leaves and white petioles.
Mild flavor, tender texture: can be substituted for lettuce
Can be ready for harvest in 3–4 weeks after sowing.
More heat tolerant than Napa cabbage. Cold tolerant to 25°F (-4°C)
Fairly bolt resistant
Advanced Plant Habitat 2018
There are two Veggie units aboard the station, along with a more sophisticated growth chamber, the Advanced Plant Habitat.
The Advanced Plant Habitat (APH) is a growth chamber on the Space Station for plant research like Veggie. It uses LED lights and a porous clay substrate, and a controlled-release “fertilizer” delivering water, nutrients and oxygen to the plant roots.
Unlike Veggie, APH is sealed, and automated with cameras and more than 180 sensors that are in constant interactive contact with a team on the ground at Kennedy, so it doesn’t need day-to-day care from the crew. It has more colors of LED lights than Veggie, and also white, far red and even infrared to allow for nighttime imaging.
APH had its first test run on the space station in Spring 2018 using Arabidopsis thaliana (good old thale cress) and dwarf wheat.
Astronauts have grown eight different types of leafy greens in Veggie at different times. NASA is building up the ingredients for a pick-and-eat salad; or rather, a pick, sanitize and eat salad since there is no way to cook on the station yet.
In 2018, the Space Station grew Dragoon lettuce, a green mini romaine. Compact and uniform. Leaves are thick and have an excellent, crisp texture. Heads are very dense, hold well in the field. Bolting and tipburn tolerant. Resistant to downy mildew, lettuce dieback lettuce mosaic virus and an aphid. For spring, summer, and fall on earth, anytime in space. Suitable for hydroponic systems. By contrast with Outredgeous, Dragoon is Utility Patent granted, meaning other people are prohibited from making, using, or selling the “invention” without authorization.
In 2019 the Space Station crew cultivated Wasabi mustard (eaten as a microgreen after 10 days of growth, or after 40-45 days as leafy greens) and Extra Dwarf pak choi (Harvest around 2-3″ tall, 30 days after sowing)
In experiment Veg-04B (see list below) with Veggie, a plant growth unit on the space station, the researchers tested how the quality of light and fertilizer affects the microbial safety, nutritional value and taste of mizuna. Astronauts completed the second of three harvests of this mildly tangy, leafy salad vegetable.
“A lack of vitamin C was all it took to give sailors scurvy, and vitamin deficiencies can cause a number of other health problems. Simply packing some multi-vitamins will not be enough to keep astronauts healthy as they explore deep space. They will need fresh produce.
Right now on the space station, astronauts receive regular shipments of a wide variety of freeze-dried and prepackaged meals to cover their dietary needs – resupply missions keep them freshly stocked. When crews venture further into space, traveling for months or years without resupply shipments, the vitamins in prepackaged form break down over time, which presents a problem for astronaut health.
NASA is looking at ways to provide astronauts with nutrients in a long-lasting, easily absorbed form—freshly grown fresh fruits and vegetables. The challenge is how to do that in a closed environment without sunlight or Earth’s gravity.”
Microbes in Space
March 2020 Researchers examined the microbial communities growing on the Space Lettuce. A diverse community of microbes lives on typical Earth-grown plants. These may include commensals (which neither harm nor benefit their host), or other microbes. Because microbes can affect the health of plants and those who eat the crops, researchers studied the communities of fungi and bacteria growing on the lettuce.
They identified the 15 most abundant types of microbes on the leaves and 20 in the roots, and found that the identity and range of these microbes was similar to Earth-grown lettuce. This was surprising, given the unique conditions in the Space Station. The scientists had expected to find different microbial communities present.
Happily, none of the bacteria they detected are known to cause disease in humans. Tests confirmed the absence of dangerous bacteria known to occasionally contaminate crops, such as E. coli, Salmonella, and Staphylococcus aureus. The numbers of fungal spores on them was also in the normal range for produce graded as fit for human consumption.
NASA astronaut Kate Rubins harvested radish plants growing in the Advanced Plant Habitat (APH) aboard the International Space Station. She carefully wrapped each of the 20 radish plants in foil, putting them in cold storage for the return trip to Earth in 2021, for further study. Note they didn’t get to eat any.
This is the first time NASA has grown radishes on the orbiting laboratory in the APH. Radishes were chosen because they are well understood by scientists and reach maturity in only 27 days on Earth, under optimal conditions. Radishes are genetically similar to Arabidopsis, thale cress, that researchers have long studied in microgravity.
Radishes are a different kind of crop from the leafy greens that astronauts previously grew on the space station, or dwarf wheat which was the first crop grown in the APH. Root crops require certain triggers to initiate root swelling, and also flowering (not wanted if you want to eat the roots!) Growing a range of crops helps determine which plants can thrive in microgravity and be part of offering variety and nutritional balance for astronauts on long missions.
Unlike previous experiments in NASA’s APH and Veggie, which used clay pillows loaded with a slow-release fertilizer, this trial relies on precise quantities of minerals.
Sophisticated control cameras and more than 180 sensors in the grow chamber let researchers at the Kennedy Space Center monitor growth and regulate moisture levels, temperature, and carbon dioxide concentration.
For the future, NASA hopes to figure out how to grow tomatoes, peppers, beans, and berries in space. And microgreens.
Overall, 15 different types of plants have grown in space in Veggie. Researchers at Kennedy Space Center have tested more than 100 crops on the ground. Click the link to read about them all.
Veggie Crops not for human consumption include more of the same crops, and also zinnias, lentils, mustards and radishes, brome grass, algae and tests of a new type of grow chamber, the Passive Orbital Nutrient Delivery System (PONDS)