Category: Lettuce varieties

Watching the Weather

Dark stormy sky over our hoophouse and solar panels. Photo Wren Vile

Farmers and gardeners have always watched the weather, and now, as the climate crisis gets worse and the weather more chaotic, we need to hone our skills. I’ve written in the past about

Where does your weather come from?

Our mid-Atlantic weather mostly comes from one of three directions,

  • mainly from the Gulf of Mexico, (wet, maybe windy)
  • the Bermuda High Pressure area in summer, (hot and dry)
  • recurrent waves of cold air from Canada in winter (from a disrupted polar vortex).
  • Due to the erratic movement of thunderstorms, some parts of our area may experience long periods of drought. September–November is the dry season but also the hurricane season.
Such grey weather! But will it rain?
Photo Wren Vile

Find a weather station that is a good match for your area, and learn how to adapt it

We use Wunderground.com for Louisa Northside, but subtract 5F° from their forecast night lows, 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. I use the ten-day forecast to get the general idea, the hourly one when planning tasks, the Roanoke animated radar on the daily page to see what’s on the way and when it’s likely to arrive, and the alerts, watches and warnings. The forecast for the month is under the Calendar tab, although the further out the forecast is, the less reliable it will be. In hurricane season I check the Severe Weather tab with the Hurricane and Tropical Cyclones information.

Make yourself a Frost Alert Card of conditions that are likely to lead to an early or late frost, so you can quickly take avoiding actions without dithering.

Learn about recent average weather at your location.

I recommend Weather Spark for browsing on a rainy day, or a too-hot afternoon. “The weather year round anywhere on earth”

Weather Spark chart of average daily temperatures in Louisa County, Virginia

I rechecked our area on Weather Spark recently and realized how much has changed since I started quoted information from our Extension Service twenty or more years ago.

  • The climate in Louisa County, Virginia, is changing on average in the past ten years to drier weather with milder winters, hotter summer nights.
  • Twin Oaks is in USDA Winter Hardiness Zone 7a: the average annual minimum winter temperature is 0°F–5°F (–18°C to –15°C).
  • The average rainfall for a year is 37” (100 cm), fairly evenly distributed throughout the year, at 2.2”–3.6” (5.6-9.1 cm) per month. October is the driest, May the wettest.
  • The average daily maximum temperatures are 49°F (9.4°C) in December and January, 89°F (31.7°C) in July. The average night low temperatures are 29°F (–1.7°C) in January, 69°F (20.5°C) in July.
  • The season from last frost to first frost, is around 211 days. The average date of the last spring frost is April 24 (later than May 7 only happens one year in ten); the average date of the first fall frost is Oct 14 (earlier than Oct 1 only happens one year in ten).

Weather SparkOn Weather Spark you can study artfully-made colorful charts of temperature, precipitation, cloud coverage, humidity and tourists (!) month by month. There is a chart of average high and low temperatures over the year, and one showing the average hourly temperature over the year (we are currently in the big red blob of hot afternoons). There’s a grey and blue chart of cloud coverage, and a green one of the daily chance of rain (with touches of blue and purple frozen precipitation). The average monthly rainfall chart is all greys, as is the snowfall one. Our greatest chance of snow is February with an average of 4.2” for the month.

You can compare your nearest city to another you might dream of moving to.

There are charts of hours of daylight and twilight, sunrise and sunset, the solar elevation and azimuth (for those planning greenhouses); moon rise, set and phases for a choice of years; and – oh – humidity! Color-coded from a comfortable green, humid yellow, tan mugginess, pink oppressive and orange misery (over 75%).

There’s a chart of average wind speed over the year; wind direction, which shows my wrong belief that most of the wind here comes from the west (true in July, December and January only). There’s also (keep scrolling) a chart about the growing season, by which they mean the longest continuous period on non-freezing temperatures, although the chart provides a very visual bigger picture of periods in various temperature bands.

There’s a Growing Degree Days chart! We’re on average at 2000 F GDD at this point in July. Next is a chart of solar energy (average daily incident shortwave solar energy), with kWh peaking in June at 6.9 per day.

There’s more details, but I’m moving on.

Check extreme weather

Lightning Strike map

For when you need to know, check out Real Time Lightning Maps.org. On the map, enlarge the area you are concerned about., and watch for the activity sparking, or click for sound. There’s an explanation of how the data is gathered and what the various color dots mean.

Windy.com has a colored map with streaming arrows, and other settings for rain and thunder, clouds, temperature and more. For those at seas, you can check the waves and swell.

AirNow.gov has a quick-to-read dial of air quality, fire and smoke maps, ozone, fine particulates, lots of information about air quality

Not exactly weather, but if you experience an earthquake, go to Did You Feel It? And register your experience. It helps USGS build a clearer picture of earthquake events in your area. You can see maps of recent earthquakes globally or a world map to give understanding of tectonic plates.

 

Book Review Practical No-Till Farming: A Quick and Dirty Guide to Organic Vegetable and Flower Growing by Andrew Mefferd

Front cover of Practical No-Till Farming by Andrew Mefferd

Book Review Practical No-Till Farming: A Quick and Dirty Guide to Organic Vegetable and Flower Growing by Andrew Mefferd, New Society Publishers, November 2022, 240 pages, $34.99. 

This is a valuable quick-start guide to small-scale and medium-scale no-till farming, for which many growers will be grateful.  Get a tarp, get started and learn as you go, reading this and Andrew Mefferd’s earlier book, Organic No-Till Farming Revolution as needed. Practical No-Till Farming cuts to the chase with a decision-making matrix for choosing the best methods at each transition point, methods that are regenerative, efficient and earn you a living.

Done well, organic no-till growing can produce more for the time you put in, while improving the biodiversity in the soil. Yields can also be higher per area, while weed management is easier and to add to the benefits, you can sequester carbon in the soil at the same time.

WHAT IS NO-TILL?

The author’s definition of no-till includes any method that doesn’t invert the soil profile. There are no-till farmers who go further and avoid growing root crops, because digging them out resembles tillage. Everyone sets their own limits. Andrew encourages all to try reducing tillage, as a step to good care of the soil.

There are many no-till methods, including covering with silage tarps, mulching with cardboard, straw, or compost. And there are many opinions on the best way to get started. Practical No-Till Farming will help you choose the methods best suited to your situation. This book includes how to:

  • assess no-till options for your farm, considering soil, climate, and the crops you want to grow;
  • balance the pros and cons, and assess the materials and the relative costs of popular no-till methods;
  • use a decision-making matrix for choosing good no-till methods at each stage of your journey;
  • maximize productivity of no-till production;
  • deal with bindweed, symphylans, and other difficult weeds and pests;
  • make a task list of what to do and when, for each no-till method;
  • learn from Andrew’s experience of organic vegetable and flower no-till market farming.

WHY DO NO-TILL?

The first 70 pages of the book, approximately, are full with the Why of No-Till. The Why is followed by about 130 pages of the How of No-Till, including advantages and disadvantages of tilling and no-till, tarping, mulching, cropping strategies, transitions between crops, and good crops to focus on. You can even skip the Why section and go straight to the How section (although you’ll probably want to come back later).

It has been three years since Andrew’s first no-till book, The Organic No-Till Farming Revolution, and many kinds of no-till are underway, (some for 10,000 years): lasagna gardening, no-dig, and permanent mulch. What’s fairly new is doing this on a farm scale rather than a backyard scale. Chemical no-till farming has taken off in the US, paired with GMO crops that don’t die when sprayed with herbicides. Without tillage, there is less soil erosion, but the runoff water from chemical no-till fields has high levels of herbicides and pesticides, so the environment is far from improved. Many organic, sustainable, regenerative farmers want to use no-till methods without pesticides, herbicides and chemical fertilizers, in order to take better care of the soil and the wider environment.

We take care of the soil biology so it can cycle nutrients to our plants. Soil micro-organisms release nutrients that would otherwise stay locked up in the soil. We can consciously farm these little creatures, ensuring they have conditions where they can thrive and thus make nutrients available to our crops. Tillage kills many soil micro-organisms, especially the larger ones, leaving the soil dominated by bacteria rather than fungi. No-till methods favor the symbiotic relationships in the soil, some of which were only discovered in the past 20 years.

Tillage burns up the organic matter. We then have to add more back to grow crops. Tillage dries out the soil, and we then have to irrigate. No-till is less wasteful, more regenerative and more profitable. This book explores the advantages of no-till in a reader-friendly informative way.

No-till farming is particularly valuable to new farmers as it does not require large pieces of land or large equipment (aka lots of money). One person with access (not even ownership) to one acre (0.4 hectare) of land, and hand tools and tarps can start a small farm with very little else, and make a living. No-till enables farming on land otherwise unsuitable: too steep, too small, an awkward shape. Also on land with contaminated soil – grow flowers, or grow food crops in containers on a tarp over the soil.

No-till gives you more flexibility about when fields are prepped and planted. Tarping allows beds to be “saved” for later. In an urgent situation, use tarps slow down the descent into chaos that can overcome a beginner farmer or one whose life has taken an unexpected turn.

Andrew is upfront about the disadvantages of no-till: soils are slower to warm up in spring, and slower to provide nutrients to very early crops; the first year or two may be difficult, as the weed pressure takes time to reduce. Some methods are hard to scale up (think about acres of tarps). Some pests flourish in high-residue fields. Field-scale no-till methods tend to suppress weeds but not eliminate them.  Perennial weeds can become a bigger problem as years go by, and you’ll have no mechanical way to eliminate them.

Author Andrew Mefferd

HOW TO DO NO-TILL

Some no-till methods require patience. You could tarp a piece of land in grass in the fall, and leave the tarp in place until spring, to plant annual crops. Tarping works by smothering plants and depriving them of light. If the soil is damp when tarped, weed seeds can germinate, but will then die due to lack of light. Tarping or heavy mulching do take longer to kill weeds, but passively: during that time you can do other tasks.

To succeed in feeding the soil, make sure the soil contains something to digest the weeds or crop debris – the soil microbiome. Take care of the micro-livestock, and they will convert the nutrients into forms the future crops can use.

Sometimes preparation for no-till involves tilling (one last time). “You can’t grow a carrot in a lawn.”  Tillage is a reset button for turning pasture or a lawn into arable land. Likely you will need to make a trade-off between using your ideal no-till method, and earning some money from your farming sooner than the year it could take to tarp the sod to death.

Some no-till methods are more suited to large areas. One example is the roller-crimper method of terminating cover crops with a crimping roller to form a mulch in place, into which the new crop is transplanted. There are special no-till drills that can plant seed into a fairly thick killed cover crop residue. These are large machines. Not all no-till growers can (or want to) plant large areas with large machines.

On a small scale, transplanting into mow-killed or roll-killed cover crops works much better than direct seeding. Likewise, transplants are easier in the looser soil of a no-till system with raised beds, where you remove the old crop, add needed compost and amendments on top, and plant the new crop. Transplants can root in rougher soil than a seed can germinate in. If seeding, the bigger the seed, the easier the task. You might be surprised to learn that most crops can be transplanted, including sweet corn, watermelon, winter squash, peas and beans. Another advantage of using transplants is that you have living roots in the soil for a higher proportion of the time, compared with direct seeding. Another is the gain of effective growing season: you may be able to grow two or three crops in sequence, because each is in the ground for several weeks less than when you direct-sow.  Sometimes transplanting the crop will be easier than making a fluffy seedbed to drill into. Transplanting one-cut lettuce rather than sowing baby salad mix, is an example of changing techniques to fit the no-till paradigm.

Compacted soil can present a challenge in no-till systems. Test by pushing a wire flag into the oil. Use a broadfork to loosen the compacted soil without turning it. Instructions and photos are in the Getting Started chapter.

Broadfork from Way Cool Tools.
Photo Way Cool Tools

To use the tarping method, first do soil tests and a test of your compost. Amend your soil as needed, let your compost mature longer if that’s what the tests indicate. Then reduce the height of whatever is growing on the land, as much as possible, by mowing or grazing. If you want the plants to rot away, be sure to run irrigation under the tarp. Dry soil will not rot plants. Cutting the plant matter into small pieces before tarping (with a weed whip or flail mower) will speed up decomposition.

Next, reduce the weed seed bank, by a process called “stale seed-bedding” where you prepare the bed ahead of time, deliberately germinate the weed seeds, then kill the weeds before the crop is planted. Tarping, (provided you leave the tarp down long enough, at least 4 weeks) can germinate and kill the newly emerging weeds.

If that doesn’t happen, you will need to manage the weeds another way. Flame-weeding of tiny weeds provides a clean seedbed. If you miss the white-thread stage of weeds, use a wire weeder, stirrup hoe (scuffle hoe), or a fine-tined weeder to kill small weeds in an existing crop, without inverting any soil. “Blind cultivation” is a method of cultivation after sowing the crop, pulling flexible fine tines shallowly (and fairly quickly) over the surface, killing white-thread-stage weeds. Blind cultivation tools were previously only available as tractor implements, but they are now also made in a manual version. You could instead, lay thick organic mulch, or a sheeting mulch over the soil. There are photos of these tools in action in the book.

Solarizing (in this case to to combat nematodes): Step on a spade to push the plastic down into a slot in the soil.
Photo Pam Dawling

Solarization in sunny weather with temperatures above 65°F (18°C), will kill existing weeds in just a couple of days. Solarization involves installing clear hoophouse plastic (UV-inhibited) in close contact with the soil, with the edges firmly held down to trap heat. There is a whole chapter on tarping (aka occultation) and solarization, with everything you need to know to start using these techniques. For small weeds, solarizing is quicker than tarping. Weed seeds and roots of perennial weeds will not die as fast as small weeds.

Mulches are inert materials put on top of the soil to keep weeds and moisture in, to keep light and weed seeds out, or both. The term includes tarps, clear plastic, landscape fabric, plastic mulch, cardboard, paper, straw, tree leaves, woodchips, thick layers of compost, and more. Organic mulches cool the soil (for better or worse), and can attract and harbor some pests (voles, slugs).

Roma paste tomatoes planted into mowed rye and hairy vetch mulch, later topped with spoiled hay. Photo Bridget Aleshire

Mulch can be grown in place, then mowed or rolled at the right stage, to kill the cover crop. Cover crops start to decompose as soon as terminated, so don’t do it ahead of time. When cover crops start to decompose, weeds start to germinate. You need to plan the timing for this system to work well: when to sow the cover crop, when to terminate, when to transplant the food crop. You need a dense cover crop planting. This system doesn’t fit with frequent plantings of small amounts of crop, but can work well for larger areas of warm-weather transplanted crops. You may have to hand-pull weeds that do come up. If your scale is too small for a tractor-mounted crimping roller, you can try the small-scale method involving two people stepping on a T-post laid across the bed. You can tarp after crimping or mowing. Keeping the cover crop dry delays decomposition.

Winter-killed cover crops provide another opportunity to transplant into mulch grown in place. This only works in early spring, and will keep the soil cooler, and the soil nutrients less available than in bare soil. Be warned – this can delay and reduce harvests of early spring crops.

There is a useful chart summarizing the turning points in a season where a decision needs to be made between one management decision or another. The beginning of season: are there few or many weeds? Time to prep beds: will you be sowing or transplanting? Time to deal with weeds: do you have mulch or not? At the end of the crop: do you have low or high crop residue? At the end of the season: will you use tarps or cover crops?

The best crops to focus on are ones that are in demand, and ones that bring a high price. If space is short, don’t grow sweet corn! One-cut lettuce, with all-small leaves can be a good no-till alternative to baby lettuce mix. Harvest and replant from plugs. You can earn more money, because of the higher yield. Harvest each new planting 30 days later (longer in midwinter). This method keeps living roots in the soil all the time. (unlike baby salad mix). One-cut lettuce has a longer shelf life and fewer brown edges than cut leaves. The seed does cost more, and you need a propagation greenhouse to grow the transplants. For many growers the disadvantages are much fewer than the advantages.

Quick crops lead to multiple crop transitions, and no-till methods make transitions quicker. Cut the old crop (and weeds) off at the soil line, add compost and amendments, and replant. Or tarp the bed, weeds and all, and replant when the residues have died. Flail mowing the residues will speed up the decomposition, whether you are tarping or not.

Andrew includes a case study growing hemp in a quarter-acre (0.1 hectare) field that had not been used for two years, and had partly returned itself to grass. He limed first, then tarped for the month of May, using a cobbled-together mix of some clear greenhouse plastic and some opaque tarps. The weather was cool and rainy (not ideal).  The tarps were removed in mid-June. Not much vegetation had survived. Andrew did a soil test, added fertilizer and 4” (10 cm) of compost, then unrolled hay on 5’ (1.5 m) centers, leaving 1’ (30 cm) unmulched in center of each bed, where the plants would go. He transplanted 4” (10 cm) seedlings, and one month later, the weeds were as tall as the crop. He spent eight hours hand-weeding, and two hours with a weed whip. The plants grew to 6-7’ (2 m) by the end of the season, and had closed the canopy, preventing any more weeds from growing. No time was saved compared to tillage method! But the weed seed bank was reduced, and the soil life was conserved, and carbon was sequestered in the soil Definitely successful!

The book finishes up with an appendix, glossary, notes, citations, bibliography, and index. A valuable resource for all of us aspiring to do less tillage, and especially for those hoping to eliminate tillage altogether.

Winter lettuce and other salad crops

Salad Mix freshly harvested. Lettuce-free mix!
Photo Pam Dawling

We are feasting on our winter salad mixes now, so I decided to write a post to encourage more people to grow winter salads.

Just how viable this is for you depends on your winter climate zone and your facilities. In the coldest of places with nowhere except your kitchen or a windowsill, you can grow sprouts and microgreens.

To grow sprouts, get some organic seeds, soak them in a jar, then fit a straining lid, which can simply be a piece of fabric held in place over the open mouth of the jar with a strong rubber band, or, if using a Mason jar, the metal ring part of the lid. Drain off the extra water, then set the jar on its side, with the seeds distributed evenly along the side. Rinse and drain twice a day, until the sprouts are the size you want. Here’s a couple of websites.

See How to Grow Sprouts at Home, by Beth, or Growing Sprouts at Home, by The SproutPeople

You don’t need to follow these directions word by word, but if you do, it will work. Other methods can also work. Just be sure to rinse and to drain!

The enthusiastic author of How to Grow Microgreens, Sylvia Fountaine, lays out a 6-step process and provides a video. Microgreens are basically seedlings, with stems and green seed leaves. Sprouts are mostly root and stem, as you may have noticed.

For those wanting to grow microgreens professionally, I recommend Andrew Mefferd’s chapter in his Greenhouse and Hoophouse Grower’s Handbook.  

I wrote about our Fall Lettuce Transition in my post Preparing your Hoophouse for Fall and Winter 9/28/22 – This post includes days to germination of lettuce at various soil temperatures. Here are dates when we sow lettuce for growing in various places (not just our hoophouse).

·        For outdoor lettuce I stop sowing August 29, transplant those 9/22 and expect to harvest them 12/10 – 12/31. I add hoops and thick rowcover when it gets cold to keep it growing.

Buttercrunch Bibb lettuce in December. Photo Kathleen Slattery

·        For winter growing in coldframes, I sow 9/1, 9/3, 9/5, 9/7, 9/9 and transplant 9/25 -10/8. Leaves from those plants can be harvested all winter until we need the cold frames to harden off spring transplants in mid-late February. We cover the coldframes with rowcover when it starts to get cold, then plastic-glazed lids as it gets colder, and quilts for really cold spells. These days we are more likely to direct sow spinach in the frames than transplant lettuce. It’s hardier and faster growing.

·        From September 11-17 we sow lettuce every other day in our outdoor nursery bed, to transplant in our unheated greenhouse (double glass windows, solid north wall, rarely freezes in there). We harvest those lettuces by the leaf all winter until we need to dig out the compost they are growing in to fill our seed flats in early February.

Lettuce growing in our greenhouse in November.
Photo Wren Vile

·        On September 15 and 24 we sow lettuce outdoors in a nursery bed, to transplant in our hoophouse 10/15 and 10/24. Those lettuces will feed us all winter, 11/16-3/1, if we simply harvest the outer leaves, rather than cut the head.

Green Panisse and red Revolution lettuce in our hoophouse in November.
Photo Pam Dawling

·        On October 23 we start sowing lettuce mix in the hoophouse. We sow successions of baby lettuce mix directly in the soil 10/24, 12/31, 2/1, 2/15. The last one, on 15 February, will be for harvest starting mid-March, and ending in May when it gets too hot. By then we should be happily harvesting juicy lettuce heads outdoors and will have lost interest in the lettuce mix. We like Fedco’s 2981LO Lettuce Mix OG or Johnny’s Allstar Gourmet Lettuce Mix #2301. For those with challenging growing conditions, both companies offer other specialized selected mixes. 1 oz (28gm) of seed sows about 600 ft, (200m) 

Baby lettuce mix in our hoophouse in winter.
Photo Twin Oaks Community

·        We sow “filler leaf lettuces” in our hoophouse 10/23, and 11/9, to use for gap filling (replacing casualties). 1/25 is our last date for filling any gaps in the hoophouse beds with lettuce plants. After that, we fill all gaps with spinach plants.

Short rows of filler greens in the north edge bed of our hoophouse in December.
Photo Kathleen Slattery

·        So, we have different “stop-dates” for the different types and locations, but no complete Lettuce Stop-date.

o   8/29 Last date for sowing for outdoor row-covered lettuce

o   9/9 last date for sowing to transplant in coldframes

o   9/21 last date for sowing for planting in an unheated greenhouse.

o   9/24 last date for sowing for planting into a double-layered hoophouse

o   11/9 last date for sowing “filler leaf lettuces”

o   2/15 last date for sowing baby lettuce mix in the hoophouse.

How should people not in central Virginia calculate their own stop dates? Using the same numbers as above for the various types and locations:

  1. ​Figure out how late in the year it’s worth having lettuces outdoors. When does the temperature drop to 20°F (-7°C)? Stop sowing for outdoors 3-4 months before then. (Our 8/29 sowing is harvested by 12/31, but our 8/20 sowing is harvested by 11/25). It’s worth experimenting to find which date works best. Outdoors, I have found that lettuce may survive an occasional dip to 10°F (-12°C) with good rowcover. Consult your Extension Service and the website WeatherSpark.com. Fill in your location and look at pages of useful info about the weather where you are.
  2. Figure when your coldframes get down to say 15°F (-9°C). This might be when the outdoor night-time low is 10°F (-12°C), lower if you have a well-insulated coldframe. We have some old quilts to roll on top of our coldframe on nights below 15°F (-9°C). Perhaps lettuce won’t make it all the way through winter in a coldframe in your climate. If so, be prepared to clear the plants when it gets too cold. Calculate back to figure when to sow – allow 4 months to get full sized lettuces.
  3. Figure when your solar double-paned-glass and masonry wall greenhouse gets down to ° (-9°C), or add a small heater with a thermostat to keep it warmer than that. Calculate back to the sowing date, allowing for the fact that plants grow quicker in a greenhouse than outdoors or in coldframes. Maybe allow 3 months.

    Our greenhouse with young lettuce transplants in early October.
    Photo Bridget Aleshire
  4. As far as daylight goes, on 9/24 everyone everywhere is pretty much getting the same amount wherever we live. With a hoophouse, the goal is to grow plants to harvestable size by the time you no longer have lettuce from outdoors (refer to #1). It probably only takes 2 months to grow a lettuce big enough for leaf harvest in a double layer hoophouse. Just be sure not to over-harvest in the winter. We have had lettuce survive a double layer hoophouse temperature of 10.4°F (-12°C) without any rowcover (sometimes called an inner tunnel), and -2.2°F (-19°C) with.
  5. At this point calculations switch to what happens after the Winter Solstice. When do you plan to start harvesting your first outdoor lettuce again? Aim for a two-week overlap with both hoophouse and outdoor lettuce available in the spring. Work back from your hoophouse harvest end date to find the last worthwhile sowing date for filler lettuces. Because lettuce bolts easily when it gets warm in spring, play it cautious. We plan to start outdoors 4/15. We stop transplanting lettuce in the hoophouse 1/25, 2 1/2 months before then. Sowing filler lettuce too late is not really a problem – you can cut it as baby lettuce. But avoid transplanting it just to have it bolt.
  6. If your climate is cold, or you don’t mind only getting one or two cuts from baby lettuce mix, you can carry on sowing it until the soil temperature reaches 86°F/30°C (max temp for lettuce germination). If it is warm, do be sure to water often, so the lettuce doesn’t turn bitter. Otherwise look to you first outdoor lettuce and clear the baby mix when the outdoor crop is ready.
Beautiful baby lettuce mix in our hoophouse in February.
Photo Wren Vile

See my post Lettuce All Year in a Changing Climate 8/31/21. It includes links to all my Lettuce of the Month series, and includes my slideshow Lettuce Year Round and our 2022 Lettuce Varieties List, to help you choose varieties we recommend for different times of year.

For ideas on mixing various crops in winter salads, see Making Salad Mix 10/31/17 and Fast Growing Vegetables 3/24/20. Winter salad mix is also known as mesclun or spring mix (even though we are growing it in the winter). Spinach and many brassicas grow faster than lettuce in cold weather, and make delicious salads.

Bulls Blood Beet leaves
Photo Bridget Aleshire

Also, check my Asian Greens of the Month posts. This post from April 2018, includes at the end links to each of the series. Many Asian Greens make great salad crops. The frilly mustards featured in this post are a good example.

For information on the temperatures that many crops will die at from cold, see Winter Kill Temperatures 2021. I was updating this list each spring. 2022 seems to have slipped by. I don’t think I had any new information, as the winter wasn’t extreme (although we had a long and memorable power outage!).

 

Planning and Growing Winter Hoophouse Vegetables

 

Hoophouse winter greens.
Photo Kathleen Slattery

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.

The Year-Round Hoophouse cover

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.

General Hoophouse Info

Winter hoophouse growing

Hoophouse video interview

Year-Round Hoophouse Vegetables slide show

Hoophouse Cool Season Crops slideshow

Hoophouse Many Crops slideshow

Hoophouse Bright Lights chard in winter.
Photo Wren Vile

Hoophouse Crop Planning

Planning winter hoophouse crops

Hoophouse Crop Rotations

Preparing for spring, sowing seeds, planning

Hoophouse Greens Clearance, Warm Weather Crops Established

Hoophouse Crops Winter 2022-2023

Hoophouse Bed Prep

Hoophouse fall bed prep

Fall hoophouse bed prep

Hoophouse bed broadforked to loosen up slumped soil. I’m happy to say our soil structure has improved in the 18 years since this photo was taken!
Photo Pam Dawling

Choosing Hoophouse Winter Crops

(see also my post categories on the right side of the computer screen, for special posts on Asian Greens, Cooking greens, lettuce and root crops)

How to decide which vegetable crops to grow

Winter-Kill Temperatures of Cold-Hardy Vegetables 2021

Spinach variety trial conclusions

September in the hoophouse: sowing spinach

Young spinach seedlings.
Photo Pam Dawling

Sow onions in a hoophouse

Frilly Mustards in our Winter Hoophouse

Three cheers for Ruby Streaks!

Yukina Savoy in the Hoophouse

Cooking Greens in December

Cooking Greens in February

Cooking Greens in March

Yukina Savoy in the early morning mist.
Photo Wren Vile

Asian Greens in October: Yukina Savoy, Tatsoi

Asian Greens for December: Pak Choy

Asian Greens for January: Chinese Cabbage

 

Green Panisse and red Revolution lettuce in our hoophouse in November.
Photo Pam Dawling

Lettuce All Year in a Changing Climate

Year Round Lettuce

Lettuce growing in October

Lettuce in December

Lettuce varieties for January

Early Lettuce Production

Cold-tolerant lettuce and the rest

Tango lettuce from our September 24 sowing on January 10.
Photo Pam Dawling

Planting in the Hoophouse (Both Transplanting and Direct Sowing)

The decision between transplanting and direct sowing

Sowing hoophouse winter crops

Seedling winter crops

Starting Seedlings

Bare Root Transplants

September sown White Russian kale (transplanted in October).
Photo Wren Vile

Keeping Every Hoophouse Bed Fully Planted and Productive

Using all the space in the winter hoophouse

Fast Growing Vegetables

Sequential Planting slideshow

Young Tokyo bekana transplant in our hoophouse .
Photo Pam Dawling

Caring for Hoophouse Crops

What makes vegetable crops bolt and how can I stop it?

You don’t want this! Bolting lettuce outdoors in July
Photo Alexis Yamashita

What to Do If Something Goes Wrong with Your Hoophouse Crops

Back-up plans for winter hoophouse crops

Plans A-D

Emergency back-up seedlings for the hoophouse.
Photo Pam Dawling

Harvesting in the Winter Hoophouse

Winter hoophouse harvests

Mid-winter hoophouse harvests

This winter week in the hoophouse

Young greens in the hoophouse

Winter Harvests

Making baby salad mix

Beautiful baby lettuce mix in our hoophouse.
Photo Wren Vile

Lettuce All Year in a Changing Climate

Lettuce bed in May.
Photo Wren Vile

We like to eat lettuce year round, and have put time and energy into finding the varieties and planting dates that work best here in Central Virginia, as well as how to get the best results in each season. Recently I revised our lettuce schedules, partly to take account of hotter weather arriving earlier in the year, and also to even out the harvest dates.

I have frequently written blogposts about growing lettuce. And I have a whole year of Lettuce for the Month posts. See here for the overview, or click on the month you want to know more about. These posts are mainly about our favorite varieties for each time of year.

I have a slideshow Lettuce year round  – It’s at the end of this post.

Back in 2006, I wrote Lettuce: Organic Production in Virginia for VABF. We’re now in Winter Hardiness Zone 7a. Back then we were 6b. Read this publication for details you are hazy on, but see our updated Lettuce Varieties List and Lettuce Log in this post.

Fast-growing Red Salad Bowl lettuce.
Photo Bridget Aleshire

Choose appropriate lettuce varieties for each time of year.

Sow several varieties each time to spread the harvest season and the risks of poor germination. I like to use something fast, something slow; at least one red; a romaine, a bibb and a couple of leaf types.

Consider multileaf lettuces too, Salanova and Eazyleaf brands. They are bred for uniformly small leaves, with more texture, loft and flavor than baby mixes and faster harvesting. Transplanted 6″–8″ (15-20 cm) apart they produce 40% more than baby leaf mixes. The full-size plant can be harvested as a head, providing a collection of bite-sized leaves.  Or just one side (or the outer leaves) of the plant can be cut and the plant will regrow for future harvests. Growing multileaf heads takes 55 days, compared to 30 days for baby lettuce

Red Hawk Farm hoophouse densely planted with multileaf lettuces.
Photo Pam Dawling

Our recent changes to our Lettuce Varieties List include switching over from “Early Spring” varieties to “Spring” varieties at the end of February rather than the end of March. This means we only make 3 sowings of the early spring varieties, and we need to stop buying much seed of those varieties! Next year I might even abolish that category and those early varieties to simplify life.

The spring varieties we now sow from February 28 to April 22. We used to sow these until May 15. We’re still making 5 sowings of those, but the dates have moved earlier.

On April 23 we switch over to our Summer varieties, which we make 20 sowings of, until August 14. (Buy lots of seed of those varieties!) We then switch to nine sowings of Fall varieties, until September 7.

Lettuce growing in our greenhouse in November.
Photo Wren Vile

From September 8 to the end of September we use our cold hardy varieties. These 9 sowings include those for the greenhouse and hoophouse, which will feed us all winter. 

Click to access Lettuce-Varieties-pdf.pdf

You’ll need a large screen, a magnifying glass or the ability to expand the image.

We like to grow a balance of leaf lettuce and head lettuces, and, in winter, baby lettuce mix too. We harvest the baby lettuce mix when 3″–4″ (7.5–10 cm) tall, cutting 1” (2.5 cm) above the soil. We harvest leaves from the big lettuces the rest of the time. Baby lettuce mix is very pretty, but I actually prefer the juiciness and crunch of big lettuce.

Beautiful baby lettuce mix in our hoophouse.
photo Wren Vile

Keys to year round lettuce

  • ·         Store seed in a cool, dry, dark, mouse proof place.
  • ·         Grow your lettuce quickly, for high quality and flavor, using good soil preparation and high organic matter.
  • ·         Learn the skills of lettuce germination in all weathers. Minimum soil temperature for germination is 35°F (1.6°C).  Optimum temperature range for germination is 68°F–80°F (20°C–27°C).1/4″–1/2″ (6–10 mm) deep is ideal.  Good light.
  • Watch the temperature – Germination takes 15 days at 41°F (5°C), 7 days at 50°F (10°C), 3 days at 68°F (20°C) and only 2 days at 77°F (25°C). Germination will not occur reliably at temperatures hotter than 86°F (30°C).
  • Keep watching the temperature –  Optimum growing temperatures are 60°F–65°F (15°C–18°C), Some growth occurs whenever the temperature tops 40°F (4.5°C).
  • ·         Choose good locations! We grow lettuce outside from transplants from February to December (harvesting from late April); in a solar-heated greenhouse from September to March (harvesting leaves from November) and in a solar heated hoophouse from October to April (harvesting leaves from November, and whole heads in April). We also sow baby lettuce mix in the hoophouse from October to February, for harvest multiple times from December to April.
  • ·         Use shade cloth on hoops in hot weather
  • ·         Use rowcover in cold weather, or plant in cold frames, greenhouses or hoophouses.

Lettuce under shade cloth.
Photo by Nina Gentle

Grow a consistent lettuce supply using succession crop planting

To have a continuous supply, it is important to plant frequently, at intervals adapted for the time of year. The gap between one sowing and the next gets smaller as the year progresses; the gap between one transplanting and the next does likewise. The number of days to reach transplant size dips to 21 days in the summer, then lengthens as the weather cools and the days get shorter.

We made a Lettuce Succession Crops graph using our records for sowing date and harvest start date. From this we determined the sowing dates to provide us with a fresh harvest (120 heads of lettuce, or equivalent) every single week. We made a Lettuce Log with our planned sowing, transplanting and harvest dates. This is explained in my slideshow Lettuce year round.

Lettuce Succession Crops Graph

Click to access Lettuce-Succession-Crops.pdf

Rouge d’Hiver hardy romaine lettuce.
Photo Bridget Aleshire

Recently I fine-tuned this in light of more recent records. In some cases we had been led astray by a spreadsheet date calculator that was based on 30 day months in a 360 day year! Not reality! We also had data showing that transplants were not always ready on the dates we had thought, probably due to a mistake in an earlier year when we were unable to transplant on time, and repeated the delayed date the next year. Most of the tweaking was in early and late spring, and then in August.

Click to access Lettuce-Log.pdf

Tips for growing good quality lettuce

I recommend transplanting lettuce (other than baby lettuce mix) at 4-6 true leaves (3-6 weeks of age). It is worth learning good transplanting skills, so that plants thrive, even if transplanted in mid-summer.

Water enough, with an efficient irrigation system. Water new transplants daily for the first 3 days, then every 4-7 days after that. Lettuce needs a relatively large amount of water throughout its growth.  Deeper weekly waterings equivalent to 1” (25 mm) of rain are better than frequent superficial irrigation – roots will grow deeper, giving the plant greater drought-resistance.

To make best use of space and time, plant lettuces 10-12” (25-30 cm) apart, in a hexagonal pattern. If you plant too close, you are restricting the size of the lettuce. If you plant with more space than needed, you will waste time dealing with more weeds!

Flats of lettuce transplants in our cold frame in April.
Photo Pam Dawling

Transplanting gets a head start on weed control, which is important from planting to a couple of weeks before harvest. Don’t waste time hoeing lettuce you will be harvesting next week. I generally find that if I hoe once, a couple of weeks after transplanting, that is all the weed control I need at the fast-growing time of year. We like the stirrup, or scuffle, hoes, which are safer in the hands of novices than sharp edged hoes, because the blade is in a closed loop.

Some growers use black plastic mulch, but I hate filling the world with single use plastic, so we don’t do that. Some others use landscape fabric with melted holes at the right spacing. I used this for strawberries and liked it. I’m not sure I’d find it worthwhile for fast-growing lettuce. No-till growers can transplant into mulch, first making what we call “nests” at the appropriate measured spacing. It’s tempting to skip the measuring, but if you drift from a 12” (30 cm) spacing to a 15” (38 cm) spacing, you will end up with fewer lettuces!

For those who like to direct sow lettuce, you could prepare the bed, let it rest for a week (watering it), then flame or lightly hoe the surface before sowing to remove a flush of weeds.

Lettuce seedlings for transplanting later. Photo Pam Dawling

Bolting and/or bitterness are more likely with under-watering, long days, mature plants, poor soil, crowding, high temperatures, and vernalization—once the stems are thicker than 1/4″ (6 mm), if plants suffer 2 weeks of temperatures below 50°F (10°C), followed by a rapid warm-up.

Bolting lettuce in July
Photo Alexis Yamashita

Deal promptly with pests and diseases. Aphids, cutworms, slugs, rabbits, groundhogs and deer all like lettuce as much as we do. If you find your lettuces melting down with fungal diseases, you can, of course, commit to better crop rotation. You can also consider solarizing beds for next year’s lettuce. You need a minimum of 6 hot weeks in which to cook the soil-borne disease spores by covering the prepared beds tightly with clear plastic. Old hoophouse plastic is ideal – construction plastic does not have the UV inhibitors that prevent the plastic shattering into shards. 

More resources

Cornell has a 2016 Organic Production and IPM Guide for Lettuce 67 pages of everything you are likely to need, for growing in New York type climates, at least.

Ray Tyler at Rose Creek farm has a Lettuce Masterclass, a step-by-step blueprint to plan, grow, and sell lettuce year-round!

This slideshow is from 2019, before I made the changes I mention above.

Lettuce Year Round 60 mins

Vegetable Seed Germination Temperatures and Phenology

Summer Lettuce Nursery Seedbed with Concept, De Morges Braun, New Red Fire and Loma lettuces.
Photo Bridget Aleshire. Lettuces are impossible to germinate if the soil is too hot. We use shadecloth (folded over on the right), a soil thermometer and ice cubes.

Vegetable Seed Germination Temperatures

Here is a table of vegetable seed germination temperatures. These apply to soil temperatures when you sow directly in the ground, and to air temperatures when you sow indoors in small containers. If your indoor air temperature is not warm enough when you want to sow your chosen crop (watermelons, anyone?) you can make a small warm place, or use a professional heat mat, or, for a small scale, germinate seeds in an instant pot! If you have one of these handy cooking devices, check the lowest setting. Perhaps labeled for making yogurt, it might be 91°F (33°C). Look at my chart below and see if your seeds will germinate at that temperature. You’ll have to experiment for the seeds which germinate well at 86°F (30°C) but not at 95°F (35°C). Don’t try this with spinach or lettuce! You might be surprised to see that some cool weather crops, like broccoli and cabbage, can germinate just fine at high temperatures!

You can see my chart is a work in progress, so if you can add any info, please leave a comment on this post. Bold type indicates the best temperature for that vegetable seed. The numbers indicate how many days it takes that seed to germinate at the temperature at the head of the column. Where I don’t know the number of days, I have put “Yes” if it does germinate at that temperature, “no” if I think it doesn’t and a question mark where I plain don’t know. I would love to know, so if you can resolve the uncertainties, please speak up! I’ve also used the words “best’, “min” and “max” which I hope are self-evident.

Vegetable seed germination

 

Ice cubes over newly sown lettuce seed, to help germination in hot weather. Shadecloth is folded open on the left. Photo Bell Oaks

Soil Thermometers

Soil thermometer.
Photo by Green Living/Taylor

To measure the temperature of the soil outdoors, I recommend a dial-type soil thermometer. Ignore the vague guidelines on Min/Optimal/Max and use the table above. The usual practice is to check the temperature at 9am each day, and if you are unsure, check again the next day. In some cases it is best to get 4 consecutive days of suitable temperatures, or even (in spring!) a few days of rising temperatures.

Harbinger weeds of spring and fall

Flowering Purple (or Red) Dead Nettle, with honeybee.
Credit Kathryn Simmons

The progress of emergence of different weeds in the spring shows us how quickly the soil is warming up. I wrote about that here. In that post you can see photos of flowering chickweed, purple dead nettle, and henbit.

Chickweed seedling.
Photo from UC IPM Weed Gallery

In the fall we will be waiting for the soil to cool enough to sow spinach. I have a blog post about this here, and also photos of those three weeds as seedlings, which is what we are looking for in the fall, as an indication that the soil has cooled down enough for them (and spinach!) to germinate.

Phenology

I have a post about phenology here.You can read some of the details of when to plant by natural signs. For instance, we sow sweet corn when white oak leaves are the size of a squirrel’s ear. I got excited this past weekend (April 10) when I saw wind-driven twigs on the ground with oak leaves definitely bigger than squirrels’ ears. But they were Red Oak, not White Oak.

The chart in that 2013 post has now got corrupted (at least it has on my screen), so here is a pdf

Phenology Record

 

A new bean bed with sunflower landmarks. When lilac is in full bloom, plant beans, squash, corn.
Photo Pam Dawling

Phenology records are a useful guide to when to plant certain crops, and a way to track how fast the season is progressing right where you are. Phenology involves recording when certain wild and cultivated flowers bloom, seedlings emerge, or various insects are first seen. These natural events can substitute for Growing Degree Day calculations. Certain natural phenomena are related to the accumulated warmth of the season (rather than, say, the day-length), and by paying attention to nature’s timetable you will be in accord with actual conditions, which vary from year to year, and are changing over a longer time-scale.

Keeping your own phenology record will help build resilience in the face of climate change. Ours might be interesting to you, but unless you live in central Virginia, you can’t use our dates. You do need to make your own. This can be a great home-schooling project, or a crew I-Spy competition, or a calming end-of-day walk around your gardens.

Winter-Kill Temperatures of Cold-Hardy Vegetables 2021

Our pond iced over.
Photo Ezra Freeman

Winter-Kill Temperatures of Cold-Hardy Vegetables 2021

I keep records of how well our crops do in the colder season, both outdoors and in our double-layer hoophouse. I note each increasingly cold minimum temperature and when the various crops die of cold, to fine-tune our planning for next year. We are in zone 7a, with an average annual minimum temperature of 0-5°F (-18°C to -15°C).

The winter 2020-2021 was mild, with our lowest temperature being a single late January night at 10°F (-12°C). We had one night at 11°F (-12°C) one at 17°F (-8°C), three at 18°F (-8°C also) and one at 19°F (-7°C). very little snow or ice. Similar to temperatures in the 2019-2020 winter.

The winter of 2018-2019 had lowest temperatures of 6°F (-14°C) in late January 2019, 8°F (-13°C) in December 2018 and a couple of 11°F (-12°C). In early January 2018, we had some extremely cold temperatures of -8°F and -9°F (-22°C and -23°C). Averaging our winter low over those four winters 2017-2021 gives 4.8°F (-15°C), within the zone 7a range.

Georgia Cabbage Collards, good down to 20F (-7C) Photo Southern Exposure Seed Exchange

New Info this winter

I’ve added in some temperatures for collard varieties (Georgia Cabbage collards, McCormack’s Green Glaze, variegated collards) from the Heirloom Collards Project, and also gained some info on spinach (Long Standing Bloomsdale), kales (Rainbow Mix Lacinato) and mustards (Chinese Thick-Stem) from Southern Exposure Seed Exchange. I’ve added in their suggestions on cold-tolerant early spring lettuces, Crawford, Simpson Elite, Susan’s Red Bibb and Swordleaf.

My results from other years still hold up.

Swordleaf lettuce on the right with another lettuce and radishes in spring.
Photo Bridget Aleshire

Using the List

Unless otherwise stated, these are killing temperatures of crops outdoors without any rowcover. All greens do a lot better with protection against cold drying winds. Note that repeated cold temperatures can kill crops that can survive a single dip to a low temperature, and that cold winds, or cold wet weather can destroy plants quicker than simple cold. Crops get more damage when the weather switches suddenly from warm to cold. If the temperature drops 5 or more Fahrenheit degrees (about 3 C degrees) from recent temperatures, there can be cold damage. The weatherman in Raleigh, NC says it needs 3 hours at the critical temperature to do damage. Your own experience with your soils, microclimates and rain levels may lead you to use different temperatures in your crop planning.

Reflect spinach in the open got damaged but not killed at -9F.
Photo Pam Dawling

Outdoor killing temperatures of crops (unprotected unless stated)

35°F (2°C):  Basil.

32°F (0°C):  Bush beans, some cauliflower curds, corn, cowpeas, cucumbers, eggplant, limas, melons, okra, some pak choy, peanuts, peppers, potato vines, squash vines, sweet potato vines, tomatoes.

27°F (-3°C): Many cabbage varieties, Sugarloaf chicory (takes only light frosts).

25°F (-4°C): Some cabbage, chervil, Belgian Witloof chicory roots for chicons, and hearts, Chinese Napa cabbage (Blues), dill (Fernleaf), some fava beans (Windsor), annual fennel, some mustards (Red Giant, Southern Curled) and Asian greens (Maruba Santoh, mizuna, most pak choy, Tokyo Bekana), onion scallions (some are much more hardy), radicchio, rhubarb stems and leaves.

22°F (-6°C): Some arugula (some varieties are hardier), Bright Lights chard, endive (Escarole may be a little more frost-hardy than Frisée), large leaves of lettuce (protected hearts and small plants will survive colder temperatures).

20°F (-7°C): Some beets (Bulls Blood, Chioggia,), 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, celeriac, celtuce (stem lettuce), some collards (Georgia Cabbage Collards, variegated collards), some head lettuce, some mustards/Asian greens (Tendergreen, Tyfon Holland greens), flat leaf parsley, radicchio (both Treviso and Chioggia), radishes (Cherry Belle), most turnips (Noir d’Hiver is the most cold-tolerant variety).

Large oat plants will get serious cold damage. Oats seedlings die at 17°F (-8°C)

Canadian (spring) field peas are hardy to 10-20°F (-12 to -7°C).

Ruby chard, good down to 15°F (-9.5°C). hardier than Bright Lights, but less hardy than green chard varieties.
Photo Kathryn Simmons

15°F (-9.5°C): Some beets (Albina Verduna, Lutz Winterkeeper), beet leaves, some broccoli and cauliflower leaves, some cabbage (Kaitlin, Tribute), covered celery (Ventura), red chard, cilantro, fava beans (Aquadulce Claudia), Red Russian and White Russian kales, kohlrabi, some lettuce, especially medium-sized plants with 4-10 leaves (Marvel of Four Seasons, Olga, Rouge d’hiver, Tango, Winter Density), curly leaf parsley, rutabagas (American Purple Top Yellow, Laurentian), broad leaf sorrel, most covered turnips, winter cress.

12°F (-11°C): Some beets (Cylindra,), some broccoli perhaps, some Brussels sprouts, some cabbage (January King, Savoy types), carrots (Danvers, Oxheart), most collards, some fava beans (mostly cover crop varieties), garlic tops if fairly large, Koji greens, most fall or summer varieties of leeks (Lincoln, King Richard), large tops of potato onions, covered rutabagas, some turnips (Purple Top).

10°F (-12°C): Covered beets, Purple Sprouting broccoli for spring harvest, a few cabbages (Deadon), chard (green chard is hardier than multi-colored types), some collards (Morris Heading can survive at least one night at 10°F), Belle Isle upland cress, some endive (Perfect, President), young Bronze fennel, Blue Ridge kale, probably Komatsuna, some leeks (American Flag (Broad London), Jaune du Poiteau), some covered lettuce (Pirat, Red Salad Bowl, Salad Bowl, Sylvesta, Winter Marvel), Chinese Thick-Stem Mustard may survive down to 6°F (-14°C), covered winter radish (Daikon, China Rose, Shunkyo Semi-Long survive 10°F/-12°C), Senposai leaves (the core of the plant may survive 8°F/-13°C), large leaves of savoyed spinach (more hardy than smooth-leafed varieties), Tatsoi, Yukina Savoy.

Oats cover crop of a medium size die around 10°F (-12°C). Large oat plants will die completely at 6°F (-17°C) or even milder than that.

Garlic shoots poking through the mulch in January. Survive down to 5°F (-15°C), and if killed, will regrow from underground.
Photo Pam Dawling

5°F (-15°C): Garlic tops even if small, some kale (Winterbor, Westland Winter), some leeks (Bulgarian Giant, Laura), some bulb onions, potato onions and other multiplier onions, smaller leaves of savoy spinach and broad leaf sorrel. Many of the Even’ Star Ice Bred greens varieties and the Ice-Bred White Egg turnip are hardy down to 6°F (-14°C), a few unprotected lettuces if small (Winter Marvel, Tango, North Pole, Green Forest).

0°F (-18°C): Chives, some collards (Blue Max, Winner, McCormack’s Green Glaze), corn salad (mâche), garlic, horseradish, Jerusalem artichokes, Even’ Star Ice-Bred Smooth Leaf kale, a few leeks (Alaska, Durabel, Tadorna); some bulb onions, yellow potato onions, some onion scallions, (Evergreen Winter Hardy White, White Lisbon), parsnips (probably even colder), salad burnet, salsify (?), some spinach (Bloomsdale Savoy, Long Standing Bloomsdale,  Olympia). Walla Walla onions sown in late summer are said to be hardy down to -10°F (-23°C), but I don’t trust below 0°F (-18°C)

Crimson clover is hardy down to 0°F (-18°C) or perhaps as cold as -10°F (-23°C)

-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.

A cover crop mix of winter rye, hairy vetch and crimson clover.
Credit Kathryn Simmons

-10°F (-23°C) Austrian Winter Field Peas and Crimson clover (used as cover crops).

-15°F (-26°C) Hairy vetch cover crop – some say down to -30°F (-34°C)

-20°F (-29°C) Dutch White clover cover crops – or even -30°F (-34°C)

-30°F to -40°F (-34°C to -40°C): Narrow leaf sorrel, Claytonia and some cabbage are said to be hardy in zone 3. I have no personal experience of this.

-40°F (-40°C) Winter wheat and winter rye (cover crops).

Hoophouse Notes

Winter crops snug in our hoophouse in a December snowstorm.
Photo Pam Dawling

Our double-plastic hoophouse keeps night time temperatures about 8F (4.5C) degrees warmer than outdoors, sometimes 10F (5.5C) degrees warmer. Plus, plants tolerate lower temperatures inside a hoophouse. The soil stays warmer; the plants recover in the warmer daytime conditions (it seems to be the night+day average temperature that counts);

In the hoophouse (8F (4.5C) degrees warmer than outside) plants without extra rowcover can survive 14F (7.7C) degrees colder than they could survive outside; with thick rowcover (1.25oz Typar/Xavan) at least 21F (11.6C) degrees colder than outside.

For example, salad greens in our hoophouse can survive nights with outdoor lows of 14°F          (-10°C). Russian kales, lettuce, mizuna, senposai, spinach, tatsoi, turnips, Yukina Savoy survived a hoophouse temperature of 10.4°F (-12°C) without rowcover, -2.2°F (-19°C) with. Bright Lights chard got frozen leaf stems.

Lettuce Notes

Lettuce varieties for a solar-heated winter greenhouse or hoophouse in zone 7a: (hardiest are in bold) Buckley, Ezrilla, Green Forest, Green Star, Hampton, Hyper Red Rumpled Wave, Marvel of Four Seasons, Merlot, New Red Fire, North Pole, Oscarde, Outredgeous, Pirat, Red Cross, Red Sails, Red Salad Bowl, Red Tinged Winter, Revolution, Rouge d’Hiver, Salad Bowl, Sylvesta, Tango, Winter Marvel, Winter Wonderland.

Cold-tolerant early spring lettuces include Buckley, Crawford, Green Forest, Hampton, Merlot, New Red Fire, Revolution, Simpson Elite, Susan’s Red Bibb and Swordleaf.

Notes on Chicories and Endives

Verona Red radicchio, hardy to about 20°F (-7°C).
Photo Southern Exposure Seed Exchange

Chicories and endives fall into two groups, but they are confusing because the common names sometimes suggest the opposite group than they are botanically. Here’s the best info I have.

Cichorium intybus, commonly called chicories, are mostly heading crops. The group includes radicchio, both Treviso and Chioggia – hardy to about 20°F (-7°C). Belgian Witloof endive (the kind for forcing chicons) is also a chicory. It dies at 25°F (-4°C). Sugarloaf chicory is the least hardy chicory, and dies at 27°F (-3°C).

Cichorium endivia, commonly called endives, are mostly loose-leaf crops, less cold-hardy than intybus types (chicories). This group includes Frisée types and escaroles, which are also known as Batavian endives. They generally survive down to 22°F (-6°C), although Perfect and President endives can survive down to 10°F (-12°C) – can anyone confirm or deny this?

© Pam Dawling 2021

Go to my Events Page for more information on these online events

Mother Earth News Fair Online: Food Independence Course Part Two was released on 3/26/21.

It consists of eight video presentations, most of which come with pdf handouts. My contribution is Growing Asian Greens, and pairs nicely with Guide to Asian Vegetables with 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.

You can subscribe to the All-Access Bundle for $2.99/month (or $35 for a year).

My previous contribution is an 8-part Garden Planning Course

I also did a workshop on Winter Cover Crops for Gardeners as part of the Winter Gardening Course.

All these and many more videos and handouts are available as part of the All-Access Bundle.

 

Early Lettuce Production

Young Salad Bowl lettuce
Photo Wren Vile

Early Lettuce Production

Growing early season lettuces involves choosing suitable types and varieties (cold-tolerant and fast-growing), having successful production methods, and a good schedule. Harvesting early in the year might mean fast production in January and February, or it might mean starting in the fall and overwintering the plants. See my post series Lettuce of the Month, for ideas on varieties and techniques throughout the year.

Our Climate Zone in central Virginia is 7a, which means our annual minimum temperature averages 0°F to 5°F (-18 to -15°C).  The average date of the last spring frost is April 30 (later than 5/14 one year in 10). We grow lettuce outside from transplants from February to December, in a solar greenhouse from October to early March, and in a solar-heated double-layer hoophouse from October to April.

Swordleaf, Red Salad Bowl and Bronze Arrow lettuces.
Photo Bridget Aleshire

Lettuce Types

There are several different general types of lettuces. In terms of growing speed, the baby lettuce mixes and the leaf lettuces produce harvests soonest after sowing. Loose-leaf lettuces are very useful because you can harvest individual leaves while you’re waiting for the heads to reach full size.

Leaf types are ready for harvest 45-60 days from direct seeding, 30-45 days from transplanting. Bibbs mature in 60-75 days, most head lettuce need up to 80 days from seeding, or 60-70 days from transplanting in spring. Romaines are slower-growing (70 days or more). Batavian lettuces (also called French Crisp) are tasty, thick-leafed varieties that have excellent heat and cold tolerance. Icebergs mature in 75-100 days.

Beautiful baby lettuce mix in our hoophouse.
photo Wren Vile

Baby lettuce can be cut 21 days from seeding, (except from November to mid-February, when it may take 2 or 3 times as long).

Bolt-resistance generally goes from Leaf types (first to bolt), through Romaines, Butterheads, Bibbs, to Crispheads.

I like to sow four lettuce varieties each time (for the attractive harvests, and to reduce the risks if one variety bolts or suffers disease): at least one red and one romaine. We have 5 lettuce seasons, with different varieties:

  1. Early Spring (Jan – Mar), 6 sowings
  2. Spring (April – May 15), 5 sowings
  3. Summer (May 15 – Aug 15), 17 sowings
  4. Fall (Aug 15 – Sept 7), 9 sowings
  5. Winter indoors, Sept 8 – 27, 9 sowings

 Lettuce Varieties

Bronze Arrow lettuce ultra-closeup. Photo Bridget Aleshire

It’s important to grow the right lettuce variety for the conditions. For earliest harvests, consider a different, faster, variety than you have usually grown. Some of the early spring lettuce varieties are often useless here if sown after mid-March, or even mid-February, because they bolt prematurely as the Virginia spring flips from cold to hot (and back again, grrr!). Varieties we only sow until 2/15 include Bronze Arrowhead (46 day leaf lettuce); Buckley, Ezrilla and Hampton (55d multi-leaf types); Merlot (60d), Midnight Ruffles (48d) and Oscarde (45d) (leaf lettuces). Antares (48d) Panisse (48d) and Revolution (38d) leaf lettuces we can sow until 3/15.

Nancy bibb lettuce
Photo Bridget Aleshire

Others that we like in early spring go on to be useful later in spring too. In this category are Buttercrunch (a small 50d bibb); Nancy (58d) and Sylvesta (52d) (two big green bibbs); Pirat (55d red bibb), Green Forest (56d), Kalura (57d) (two green romaines); and New Red Fire (55d), our reliable Salad Bowl (45d) and Red Salad Bowl (46d), Starfighter (52d), and Swordleaf (53d) (leaf lettuces)

New Red Fire lettuce.
Photo by Bridget Aleshire

The baby lettuce mixes we like are Fedco’s 2981 LO Lettuce Mix OG (contains at least six different lettuces) or Johnny’s Allstar Gourmet Lettuce Mix #2310 (including green and red oakleaf, green and red romaine, lollo rossa, and red leaf lettuces). One gram sows 25 ft, one ounce will sow about 600 feet.

For those with challenging growing conditions, both companies offer other specialized selected mixes.

Cold-tolerance of lettuce

Red Tinged Winter and Tango lettuce in our hoophouse in December.
Photo Pam Dawling

Lettuce is more cold tolerant than many people realize. If plants are sufficiently hardened (prepared by growing in gradually lower temperatures), they can withstand freezing. At 22°F (-6°C), large leaves of some lettuce will die. Medium-sized plants with 4-10 leaves (Marvel of Four Seasons, Olga, Rouge d’Hiver, Tango, Winter Density may survive unprotected down to 15°F (-9.5°C). Half-grown lettuces are more cold-hardy than full-sized plants.

Lettuce Crop Requirements

Flats of lettuce transplants in our cold frame in April.
Photo Pam Dawling

Lettuce seed remains dormant unless triggered by adequate levels of light and temperature. It needs light to germinate, so don’t sow too deep: ¼-3/8″ (6-9 mm) is enough. Some sources recommend not covering the seed at all, but this can make it hard to keep the seed damp. The light dormancy is more pronounced in fresh seed, which has higher levels of the hormone that controls germination.

Soil temperature is important. I have a table of optimum soil temperatures for germination in The Year-Round Hoophouse The optimum temperature range for lettuce germination is 68-80°F (20-27°C). It takes 7 days to germinate with a soil temperature of 50°F (10°C) or 15 days at 41°F (5°C), and only 4 days at 59°F (15°C). Even a few hours at temperatures higher than the optimum can induce dormancy.

Lettuce transplants prefer a well-draining soil high in organic matter, and with a pH of 6.0-7.0, not lower. Optimum growing temperatures are 60-65°F (15-18°C), with a minimum of 40°F (4.5°C) for any growth to occur. Lack of water will lead to bolting, and/or bitterness. Keep them growing quickly for good flavor.

Lettuce in January

A flat of newly emerged lettuce seedlings
Photo Kathryn Simmons

We plan to start harvesting heads of lettuce outdoors from April 15. Before then we will harvesting lettuce in our greenhouse and hoophouse.

In mid-January we sow four lettuce varieties, to become our first outdoor transplants. I recommend sowing several varieties each time to spread your risks, if one kind bolts or suffers disease. I choose varieties that cover the range of colors and shapes. I select hardy types that are fast-maturing. Buttercrunch green bibb lettuce is one of my favorites for early spring. One of the Salad Bowl lettuces, red or green, is also usually in my first sowing. The Salad Bowls are so reliable and productive! New Red Fire has become another reliable lettuce stand-by for us. It was suggested to me by neighboring Virginia farmer, Gary Scott of Twin Springs Farm. It is more of a leaf lettuce, and doesn’t exactly head up, although it can be cut as admittedly lightweight heads. It works fine as a leaf lettuce, harvested by the cut-and-come-again method. We grow New Red Fire year round, it’s that adaptable and easy-going. We haven’t found many good full-size red romaines. Bronze Arrow  has worked well for us and we were harvesting it in early May.

We grow all our outdoor lettuce as transplants. In spring we sow in 3″ (7.5cm) deep open wood seed flats, 12″ x 24″ (30 x 60cm). We make four little furrows by pressing a 12″ (30 cm) plastic strip (aka a ruler!) into the seed compost. We sow the seed, label it, cover it lightly, water, and put the seeded flats in our germinator cabinet. The first flat of the year takes about 9 days to germinate.

Spotting cabbage seedlings from a seed flat into a transplant flat.
Photo Wren Vile

Once the seedlings are big enough to handle, we spot them out into 4″ (10 cm) deep flats (also 12″ x 24″/30 x 60cm). We have a plywood dibble board with pegs evenly spaced about 2.5″ (6 cm) apart. We aim to harden off the lettuce for two weeks in the cold frame before transplanting into the garden beds with thick rowcover on hoops to protect the lettuce from the still-cold outdoors. To be ready for harvest 4/15, these seeds have to become full size lettuces in 88 chilly days.

Seeds can instead be sown in cell packs or plug flats, putting three seeds in each cell, and later reducing to one seedling with scissors. Cells or pots with diameters from 1-2½” (2.5-6cm) can be used. The 96-cell size (1×1½”/2.5x4cm) works well, although the 200-cell size (1×1”/2.5×2.5cm) is possible if you can be sure to get the transplants out before they get root-bound. If warm germination space is limited in early spring, sow seed in a small flat, then “spot” the tiny seedlings into bigger flats, 606 (2×2¼”/2.5x6cm) cell packs, or 32-pack square pots to grow on in cooler conditions before planting out. Soil blocks are also possible, but take more time.

We make a second sowing on January 31. The intervals between sowings at the beginning of the year are long, because later sowings will catch up to some extent with earlier ones. Most crops grow faster in warmer weather.

Lettuce in February

We sow lettuce twice in February – 14 days apart. We get ready to transplant our first outdoor lettuce, to feed us mid-late April. Our first sowing of baby lettuce mix in the hoophouse comes to the bitter end, and the second sowing is awaited. We continue to harvest leaves from the large lettuce we transplanted in the hoophouse in October.

Lettuce in March

Lettuce with sclerotinia drop.
Photo Pam Dawling

We sow flats of lettuce every 10 days in March. March 9 is our goal for a transplanting date outdoors for our first 120 lettuce (about one week’s worth for 100 people).

Here is a link to a helpful publication from eXtension: Disease Management in Organic Lettuce Production. Horribly useful photos!

Baby Lettuce Mix

Baby lettuce mix can be ready in as little as 21 days from mid-spring to mid-fall, longer in early spring. A direct-sown cut-and-come-again crop, the plants regrow and can be harvested more than once in cool seasons. We sow 10 rows in a 4’ (1.2m) bed, 4.5” (11cm) apart. Weed and thin to 1″ (2.5 cm). When 3″–4″ (7.5–10 cm) tall, cut 1” (2.5 cm) above the soil. Gather a small handful in one hand and cut with using large scissors. Immediately after harvesting, weed the just-cut area so the next cut won’t include weeds. Rake after harvest with a fine leaf rake to remove outer leaves and cut scraps. If you want to make more than one cut, you will need to remove anything that isn’t top quality salad while you can see it. Larger scale operations have harvesting machines.

 

Growing Vegetables in Space — Eat Like an Astronaut

Tokyo bekana in our hoophouse in late December.
Photo Pam Dawling

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 green here 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.

Young Outredgeous lettuce in late November. The persistent galinsoga shows that our hoophouse has not yet reached freezing temperatures.
Photo Pam Dawling

The first vegetable grown and eaten on the International Space Station space was Outredgeous red romaine lettuce, in 2015. Bred by Frank Morton of Wild 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!

Read Astronauts are about to eat the first food grown in space 2015.  The lettuce was grown for 15 months [? I think several rounds of planting], and the astronauts cleaned the lettuce with citric-acid-based sanitizing wipes before eating it.

Outredgeous lettuce growing in the Veggie module. NASA photo

Space Hydroponics – Veggie 2015

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.

See the 2015 article Meals Ready to Eat: Expedition 44 Crew Members Sample Leafy Greens Grown on Space Station

Watch this video to learn more about growing plants in space: https://www.youtube.com/watch?v=YFdwv9yrxD0&feature=youtu.be

For technical information about Veggie, visit here, and also see the 2020 Veggie Fact Sheet

2017-2018 More Space Crops

Next up in 2017 was our friend Tokyo bekana (a frilly Japanese mustard greens).

NASA photo

See the Modern Farmer article from February 2017: The Astronauts on the International Space Station Are About to Harvest Chinese Cabbage (Tokyo bekana)

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.”

Waldmanns Dark Green lettuce https://www.johnnyseeds.com

Next the cut-and-come-again harvest method was tried with a few leafy salad greens using: Mizuna mustard, Outredgeous red romaine lettuce and Waldmann’s Green lettuce.

Green mizuna in our hoophouse in November.
Photo Pam Dawling

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.

————————————————

Asian greens divide into 3 groups:

  1. The turnip family, Brassica rapa, of Asian origin

Some crops are Brassica rapa pekinensis (napa cabbage, michihli, celery cabbage);

Others are Brassica rapa var. chinensis (bok choy): Tokyo bekana is either Brassica rapa var. pekinensis or var. chinensis

Brassica rapa var. japonica (mizuna),

Brassica rapa var. narinosa (tatsoi),

Brassica rapa var. perviridis (komatsuna)

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

————————————————

Astronaut Serena Auñón-Chancellor harvests red Russian kale and dragoon lettuce from Veggie on Nov. 28, 2018, just in time for Thanksgiving. The crew got to enjoy a mid-afternoon snack with balsamic vinegar, and Auñón-Chancellor reported the lettuce was “delicious!”
Credits: ESA/Alexander Gerst

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.

Dragoon lettuce, Johnny’s Seeds

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.

Another 2018 crop was Red Russian kale

Red Russian kale March 7
Photo Pam Dawling

Recent Space Veggies 2019-2020

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)

Wasabi mustard. Photo Specialty Produce

 

Extra Dwarf pac choi, Kitazawa Seeds


Astronauts Enjoy Space Veggies and Look to the Future of Cosmic Salads Nov 2019

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.

Growing Plants in Space | NASA, January 2020

“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.

The Next Frontier -Roots in Space

On Nov. 27, 2020, NASA astronaut and Expedition 64 Flight Engineer Kate Rubins checks out radish plants growing for the Plant Habitat-02 experiment that seeks to optimize plant growth in the unique environment of space and evaluate nutrition and taste of the plants.
Credits: NASA

See the latest (December 2020) Astronauts Harvest Radish Crop on International Space Station

Watch Radishes Growing in Space: 27 Days in 10 Seconds

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.

For more generally space diet info, see: Space Food Photos: What Astronauts Eat in Orbit 2013

All Veggie Crop Experiments for Human Consumption 2015-2019

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)

Cuban Agroecology Tour: Finca Agroecológica El Paraiso, Viñales

Finca Agroecológica El Paraiso, Viñales. View from the restaurant
Photo Pam Dawling

Cuban Agroecology Tour: Finca Agroecológica El Paraiso, Viñales

Here’s another post from my January 2020 group agroecology trip with Organic Growers’ School to Cuba. I’m posting about this sporadically as I organize my photos and journal.

Day 5 – Saturday January 11 lunch and afternoon

After visiting La Palma, a farm in Pinar del Rio province primarily growing tobacco, and Manolo Tobacco Farm to see cigars made, we went to a farm restaurant called La Finca Agroecologica el Paraiso. Wilfredo is the main farmer and his daughters are the main chefs.

Tidy raised beds and mountain view, Finca Agroecológica El Paraiso, Viñales, Cuba.  Photo Pam Dawling

The farm has 8.9 hectares, with 200 vegetable beds and 80% of the produce is sold through their restaurant, and 20% to hospitals etc (I think that is a legal requirement in Cuba). The restaurant is at the top of the hill, affording beautiful views of the farm.

Part of the vegetable gardens at Finca Agroecológica El Paraiso, Viñales, Cuba. Photo Pam Dawling

We had an exceptionally delicious lunch starting with an anti-stress herbal cocktail. Following that we had squash soup, sweet potatoes, taro, squash, lettuce, cabbage, cucumbers, pickled beans, pickled cucumbers, pork, beef, fish, rice and beans. The most vegetables I ate all week! (Food for tourists tend to be meat focused, although the places we visited could cater for vegetarians and vegans.) We enjoyed flan for dessert.

Outdoor classroom and banana tree at Finca Agroecológica El Paraiso, Viñales, Cuba
Photo Pam Dawling

After lunch we were given a guided tour of Finca Agroecológica El Paraiso. The boxed beds were very tidy, and they are all hand watered with water pumped from the river.

Creole spinach – does anyone recognize this plant? Finca Agroecológica El Paraiso, Viñales, Cuba.  Photo Pam Dawling

Creole spinach – see photo above. I do not know the Latin name for this vegetable, and in my research of hot weather cooking greens, particularly alternatives to spinach, I had not come across this crop before. Leave a comment if you know what it is.

Star garden at Finca Agroecológica El Paraiso, Viñales, Cuba
Photo Pam Dawling

Their “summer lettuce” is Tokyo bekana or maruba santoh. This use of the fast-growing chartreuse tender-leaved Asian green for a salad leaf was one I saw several times in Cuba. I thought I’d invented it! Haha! One summer when our lettuce did not grow according to plan, we served some Tokyo bekana as lettuce, and many people did not notice a difference! (Enough salad dressing will mask any vegetable flavor!) Some farms and restaurants simply call it “lettuce” or “summer lettuce”, some say it is a kind of pak choy, and a few can provide the actual name.

Finca Agroecológica El Paraiso , Viñales, Cuba. Tokyo bekana used as “summer lettuce”. Photo Pam Dawling
Herbs and flowers growing at Finca Agroecológica El Paraiso, Viñales, Cuba.
Photo Pam Dawling

The farm grows aromatic herbs to deter bugs. They use tobacco stem solution to kill pests. Nicotine is a strong generalist poison, which used to be part of the toolkit of organic growers here in the US and in the UK. It has the advantage of being short-lived, so produce can be eaten the day after spraying.

Finca Agroecológica El Paraiso, Viñales, Cuba. Lettuce bed. Photo Pam Dawling

See this video from Franny’s Farmacy. Made by two of my fellow travelers on the OGS Tour.

Finca Agroecológica El Paraiso, Viñales, Cuba – Learning about Sustainability and Organic Farming https://www.youtube.com/watch?v=egnKXHyu8_k

To see more, visit https://vimeo.com/146862523