Root Crops in July

 

 

A fine rutabaga (Swede)!
Photo Produce Market Guide

Root Crops in July

Root Crops to Plant in Central Virginia in July

July is not a good month for sowing many root crops in Virginia – it’s hot and for most fall root crops we can do better waiting till August. Yes, it will still be hot in August, but the daylight is getting shorter and so the hot part of the day is also getting shorter. 

Carrots: if we really need more carrots, we direct sow our eighth bed of carrots in early July. We only do this if they’re really needed, because carrots grown in hot weather do not have the best flavor. They will not be sweet, they may even be bitter.  Our plan is to have grown enough between February and May to last us until late October, stored in perforated plastic bags in the walk-in cooler. But if earlier sowings weren’t all successful, or we ate unusually large amounts of carrots, we can find ourselves sowing them in July.

Use shadecloth to keep the soil damp, or water a lot. Carrot seed will germinate whenever the soil is below 95°F (35°C), provided you can keep the soil damp until the seedlings emerge. You won’t need to do daily watering for long: maybe only 4 days. We flame summer carrots on day 4 after sowing, because we have found that carrots can emerge on day 5 in summer temperatures, despite longer times given in the charts. See Root Crops in May for more about sowing and growing carrots, including pre-emergence flame weeding.

Young kohlrabi plants.
Photo Kathryn Simmons

Kohlrabi: Kohlrabi transplants successfully, unlike carrots and turnips, and this has usually been our method for fall crops. We have sown kohlrabi (Early Purple Vienna and Early White Vienna) in the week beginning July 2, for transplanting 8/3-8/9. Sowing in early August is also possible, for November harvests. Kohlrabi, like other brassicas, can be grown in spring or fall in our zone 7 climate. It’s not actually a root crop, rather a swollen stem, but I’m including it as an “acting root”

Rutabagas: This year we are growing rutabagas (also known as Swedes) again, after several years when we went with more turnips instead. Rutabagas are only sown here in late summer for winter storage. They take longer to grow to a good size than turnips do, so it is necessary to start earlier: 7/15-8/4 here, (mid-August at the latest), allowing 90-100 growing days before a hard freeze. Fall root crops sown too early in the summer can get woody. See the Special Topic for July below for all the details about rutabagas.

Root Crops to Harvest in Central Virginia in July

Potatoes: From mid-June onwards, we can harvest spring-planted potatoes as delicious “new” potatoes. See Root Crops in June for more on this. For maximum yields, hold off on harvesting until two weeks after tops have died. See next week’s post for all the details.

This garden worker loves washing beets!
Photo Wren Vile

Beets: We like to clear all our spring beets by the end of June, but sometimes the job flows over into July. Trimmed beets keep well in perforated plastic bags under refrigeration. Store beets at 32°F (0°C) and 95% humidity.

Carrots: Our third carrots (sown mid-March) should be cleared in early July if not before, and our fourth carrots (sown in late March) and fifth (sown in mid-April) will also be ready to harvest in July. I usually reckon on three months from sowing to harvest for carrots, but they can be faster in warm weather. Don’t leave them in the ground too long, or they will get woody. See Root Crops in June for more on carrots.

Kohlrabi: As with beets, we plan to harvest spring kohlrabi by the end of June, at 3” (7.5 cm) in diameter (or even up to softball size). They get too fibrous if left longer, so we will prioritize getting them up. The base of the globe can be tough, so cut either the wiry root just below the soil surface, or cut higher, leaving a small disc of the globe behind, attached to the taproot.

Turnips:  If we didn’t finish harvesting our spring turnips by the end of June, we really need to get them all up in early July. If we have more than we can eat in the next week, we store them in perforated plastic bags in the walk-in cooler, eating them during the summer. Turnips keep for about 4 months at temperatures close to freezing and humidity of 90-95%. Higher humidity will make them rot (rotting turnips are pretty unpleasant!)

Harvested Purple Top Milan and White Egg turnips.
Photo Pam Dawling

Other Root Crop Tasks in Central Virginia in July:

After all the spring-sown root crops are harvested, and the spring-sown greens have bolted, we prepare the emptied beds for summer or fall crops.

Preparing space for summer-planted crops

In July, we will be looking for beds to plant successions of lettuce, cucumbers, squash and beans; our fall brassica transplants, and our first transplants of fall and winter cabbage and Asian greens. In August, we’ll want beds for our last plantings of cucumbers, squash and beans, the never-ending lettuces, fall beets, turnips, winter radishes, kale, and collards. Harvesting the spring roots promptly and storing them gives us time to prepare the beds for their next crop.

Buckwheat cover crop in flower.
Photo Pam Dawling

Buckwheat

If we have 4 weeks or more before the next crop, we will sow a cover crop of buckwheat in the just-emptied beds. Buckwheat keeps the weeds down and feeds the soil (and the honeybees and other pollinating insects). If there are weeds or lots of crop debris, we will till deep enough to bury that plant matter, then broadcast the buckwheat at a rate of 2–4 oz/100 ft2 (6–12 gm/m2), give another shallow tilling, then water and stand back. If there are no weeds or crop debris, there’s no need to till: you can broadcast the seed, and rake it in before watering (and standing back!). As an alternative to broadcasting you can sow rows of buckwheat with the #22 plate on an EarthWay seeder.

Prepare stale seed beds for fall carrots

If you have less than four weeks before you need to sow or transplant the next crop, you can use the time to kill weeds with the stale seedbed technique. Prepare the bed as if you were about to sow, producing an even surface with a fine tilth (surface texture). Then water as if you had sown something, keeping the surface damp by watering as needed. As soon as you see tiny weeds germinating, hoe the surface very shallowly in sunny breezy weather and let the weeds dry out. Make a last hoeing the day before sowing the next crop. This is especially useful for carrots, scallions or anything with tiny seedlings, which cannot easily compete with weeds.

Another method of germinating and killing weed seedlings when there is no crop in the ground is tarping: cover the bed with an opaque waterproof cover after watering the soil. Weeds seeds germinate, but the weeds cannot grow without light and will die.

Solarizing with clear plastic. Photo Pam Dawling

Solarizing is another approach that works well in hot weather: cover the prepared bed with clear agricultural plastic, such as scraps of a hoophouse covering. The heat of the sun bakes any weed seeds near the surface, and also any disease spores or small pests. Larger creatures such as earthworms can burrow deeper into the soil (as they do anyway in hot weather).

Rutabagas, although these ones don’t have much in the way of necks, a usual distinguishing feature.
Photo Penn State

Special Root Crop Topic for July in Central Virginia: Rutabagas

Rutabagas need to be sown in July in central Virginia. To clarify: rutabagas (known as Swedes in the UK) are Brassica napus, closely related to most other brassica crops. Botanically, rutabagas are part swollen tap roots, part swollen stem (the upper portion of the vegetable which forms the neck, the distinguishing feature of rutabagas). There are secondary roots growing in two rows down the sides of rutabagas. Rutabagas are mostly yellow-fleshed with a tan and reddish or purplish skin, although there are white-fleshed varieties. They all have blue-green waxy, non-hairy leaves. turnips are Brassica rapa, like Chinese cabbage and mustards. Turnips come in a range of colors, white or yellow flesh, with white, purple, red or golden yellow skins. The leaves are bright grass green, usually hairy, and not waxy. Turnips do not have a neck or secondary roots growing off the turnip. Rutabagas have twice the nutrients of turnips. And take longer to grow.

Rutabagas are among the hardiest of vegetables, and can be left growing (or at least not dying) until all other crops have been harvested. The flavor improves after frost. For small plantings, plan on 10’ (3 m) per person. Yields of rutabagas can be 75-180 lbs of roots/100’, (35-80 kg roots/30 m): 50% higher than turnips.

Rutabagas come in very few varieties. Laurentian (95 days OP) has a deep purple crown and cream yellow bottom. The uniform 5–6″ (13-15 cm) roots have sweet pale yellow flesh. Joan (90 days, OP), looks similar to Laurentian, with the added advantage that it is somewhat tolerant to club root. Gilfeather (85 days, OP) is sold as a turnip, but is botanically a white rutabaga. Sweeter and later to mature than turnips, it doesn’t become woody even at softball size. Southern Exposure Seed Exchange also has American Purple Top (not to be confused with the Purple Top White Globe turnip) and the Lithuanian Nadmorska a large oval 90d OP.

Fine rows of rutabagas. See the distinctive necks.
Photo Nan Chase

Keys to growing mild, sweet-tasting rutabagas include cool temperatures, sufficient irrigation, and no competition from weeds or over-crowding. The optimal germination range is 59-95°F (15-35°C). Rutabagas are a little slower to germinate. We sow four rows in 4’ (1.2 m) wide beds. Seeds need to be 0.5” (1.2 cm) deep. When flea beetles or grasshoppers are a problem, use rowcover or insect mesh.

Early thinning is especially important for shapely well-developed rutabagas. Thin to 4” (10 cm) within 10 days of emergence, or at least by 1” (2.5 cm) tall, then to 10” (25 cm) when 2-3” (5-7.5 cm) tall. If not well-thinned, they will grow in odd shapes and be small. 

Boron deficiency causes the middles of the roots to turn brown. Many common weeds are in the Brassica family, and could harbor pests and diseases that could attack the crop, so use crop rotations, stale seedbeds and clean cultivation to remove the weeds.

Aphids, flea beetles, cabbage worms, harlequin bugs, and grasshoppers can all be a problem. Rutabagas have worse trouble with aphids than turnips. Brassica flea beetles are not the same species as the nightshade flea beetles often found on eggplant. Rowcovers or insect netting and the planting of insectaries (flowers to attract beneficial insects such as ladybugs) can help avoid the problems. Bt can be used for the caterpillars, soaps for the aphids and Nolo bait for the grasshoppers (except where banned in order to preserve rare species of grasshopper).

More information 

GrowVeg Rutabaga Growing Guide 

Written in Vermont: Gardener’s Path:

Written in Mother Earth News by Sara Pacher:

DIY Network

The main diseases of rutabagas (and turnips) are club-root, downy mildew, powdery mildew, rhizoctonia rot, bacterial scab, and blackleg. All except scab are fungal diseases. Organic methods of prevention are crop rotations and field sanitation (plowing in residues promptly, removing weeds). Club-root fungus is able to live in the soil for up to 10 years, so is hard to eliminate. Avoid all brassica crops in an affected field for 10 years, and be vigilant about eliminating brassica family weeds. (Develop a fondness for spinach, chard and beet greens!)

Our rutabagas are ready from mid-October. Rutabagas (but not turnips except in warm climates) can be stored in the ground all winter. Mulch over them with loose straw once the temperatures descend near 20°F (-7°C). If you don’t manage to eat all the roots before spring, they will re-sprout and you can have an “early spring bite” of greens (a term more usually used for cattle fodder crops).

Rutabagas can store for as much as 6 months in perforated plastic bags under refrigeration. They do best stored above 95% humidity. Prompt washing before the soil dries on the roots will make them easier to clean later.

In the UK, rutabagas are not waxed as they are in North America. In fact, they store well without waxing, and I encourage you to try skipping the petroleum product.

Sliced rutabaga.
Photo Cornell

Book Review: The Organic No-Till Farming Revolution: High Production Methods for Small-Scale Farmers, Andrew Mefferd,

The Organic No-Till Farming Revolution: High Production Methods for Small-Scale Farmers, 

Andrew Mefferd, New Society Publishers, January 2019, $29.99

Organic No-Till has been an unachievable goal for many of us, but there’s no need to feel guilty or ashamed! We may understand the biology, and even the physics and chemistry of it, and why it’s a Good Thing. We can see how it can be done on a domestic scale, especially by those who can grow or buy lots of mulch, and especially if there’s no need to account for time and money invested.  There is equipment (roller-crimpers and no-till planters) that makes large scale organic no-till possible and efficient. But for those of us growing food in the middle scale, it’s proving harder. Giant equipment works for acres of soybeans but not for market farming. How to keep the weeds away while tending forty sowings of lettuce? The Organic No-Till Farming Revolution provides very practical information for those who want to increase the amount of no-till growing on their small-scale farm.

Andrew Mefferd says in the introduction, “No-till is as much about climate change as it is about soil health as it is about farm profitability.” Work on all three at once with this book. 50-70% of the world’s carbon in farm soils is off-gassed due to tillage (according to a Yale study). This decreases soil fertility at a time when we need to grow more resilient crops to cope with climate change. Global food production could be reduced by up to 17% by 2100 due to climate-induced crop failures. All steps in a good direction are worth taking.

Andrew is not a proselytizer and this is not a religion. You don’t have to commit to permanent no-till everywhere to benefit from some very practical new skills, enabling you to increase the area in no-till practices. Different strategies work for different farms and different crops. Not inverting the soil layers is important. Any reduction in tillage is a good step; shallower is better than deeper; less often is better than after every crop. The tilther and power harrow on a shallow setting are used by some no-till farmers. One last tilling before setting up permanent beds is OK if that’s what you need to do! Think in terms of doing more no-till and take away any pressure to feel bad if you continue to do some tilling. One step at a time towards healing the earth, the climate; improving your soil and your crops.

The first part of the book explains the concepts and presents various methods: mulch grown in place; applied cardboard, deep straw or compost; occultation (tarping) and solarization (clear plastic). The main section consists of in-depth interviews with seventeen farmers about what works for them. After reading the first part, you can dive into the chapters with the methods that most appeal to you. The book is written so it doesn’t have to be read sequentially to make sense.

Andrew worked at Virginia Tech’s Kentland Research Farm on organic no-till vegetable production, using roller-crimpers and no-till drills. The next year he moved to a 3 acre farm and temporarily forgot about no-till because the methods he’d seen were not applicable to that scale. Ten years later, in 2016, he read articles in Growing for Market magazine, and attended conference workshops by farmers who were succeeding with organic no-till on smaller farms. These growers were using various different methods, and Andrew decided to visit them and write up the interviews.

“Want to build organic matter and soil biology because of the way you grow, instead of despite it?” Andrew asks. Increasing the organic matter in the soil will help the soil hold more water, suffer less from run-off and need less applied water per year (1″ (2.5 cm) of water saved per 1% increase in OM has been quoted). Carbon is stored in the soil, keeping it out of the atmosphere. Paying attention to the soil biology and feeding the soil is the heart of organic farming. We must farm more ecologically if we want to survive. At the same time, small-scale farms must be profitable to sustain the farmers. This book has many examples of farmers that started small with limited resources, and are able to make a decent living. Avoiding the need to buy heavy machinery is a big saving.

I love this surprise quote: “Tilling the soil is the equivalent of an earthquake, hurricane, tornado and forest fire occurring simultaneously to the world of soil organisms.” Which outspoken radical farming group made this proclamation? The USDA-NRCS! Taking care of the soil biology reduces the urge to compensate with chemistry. The less tillage, the better-off we can be. OM levels can rise quickly when tillage is reduced. Cover-cropping, adding compost and organic mulches are all ways to achieve this. The churning of tillage burns up OM. As Bryan O’Hara of Tobacco Road Farm, Connecticut, says, “Tillage is a nutrient flush from all the death you just wrought on the soil…Tillage doesn’t give nutrient balance, it gives you nutrient release.” More OM must be added every year just to maintain levels that were there before tilling.

Tarping is a rediscovered method that lets the soil digest the plant material without any tilling. This is especially useful when you have several weeks to spare after a harvest, but not enough time to grow a cover crop. The soil biology breaks down the residue, weed seeds germinate then die. The soil is left ready to replant.

After listing all the many benefits of no-till, Andrew explains the disadvantages. Weed control without cultivation is the main issue, especially perennial weeds. The slowness of mulched soil to warm in the spring is another. A third is that high OM can lead to more slugs. If you mulch with tree leaves, you might find squirrels and chipmunks rummaging for acorns. Grass creeps in from the edges. These problems are all addressed in the book.

Andrew Mefferd
Photo by Ann Mefferd

The Overview of Organic No-Till Techniques is a summary of methods, biodegradable mulches and plastic sheet materials.

Biodegradable mulch grown in place is the method we used for many years for our large planting of paste tomatoes. We sowed winter rye, hairy vetch and Austrian winter peas in early September, following our spring broccoli and cabbage. At the beginning of May we mowed down the cover crop with our hay cutting machine and the next day dug holes and transplanted the tomatoes. We used a small shovel for our big transplants. Shawn Jadrnicek suggests using a stand-up bulb planter. The legumes provided all the nitrogen the crop needed, and the long-cut cover crop kept the weeds at bay for maybe 6 weeks. By then we had trellised the tomatoes and were able to unroll big round bales of spoiled hay between the rows. This dealt with the weeds for the rest of the season. One year in ten in our row crops rotation was no-till. We tried a few other applications of this method but generally they didn’t work as well. We were unable to direct-seed into cut mulch, for instance. Our watermelons didn’t like the cold soil, and we wanted watermelons in August, not October! To grow big enough cover crops for this to work, the food crop has to be planted no earlier than late April in central Virginia. Paste tomatoes worked well because we didn’t need an early harvest. Transplanted Halloween pumpkins and winter squash work. Fall cabbage and broccoli (on German millet and soybeans) can also work.

Bringing in biodegradable mulch (hay, straw, cardboard, paper, compost, tree leaves, wood chips, spent brewers’ grains) is the second method. The material needs to be spread thickly, usually 3″ (7.5 cm) or more and used appropriately (don’t switch plans and till in raw wood chips!). Straw can cost $750 per acre covered. A round bale covers about 200′ by 5′. We use hay bales or biodegradable plastic on annual crops, cardboard and wood chips around our fruit plantings. The existing weeds and crop residues will need to be removed first. Flaming works for small weeds, otherwise use one of the sheeting methods. Read the book to get the all-important details on how to be successful.

The non-biodegradable mulch methods are tarping (occultation) and solarizing. Tarping was introduced to most of us by Jean-Martin Fortier in The Market Gardener. For annual no-till crops, first tarp the soil using an opaque material such as silage tarps (or solarize in hot weather). After killing the weeds, uncover, spread mulch and transplant into it. Tarps will not kill docks or nut-sedge. Tarping takes from 3-6 weeks, (the shorter time in hotter weather). Allow longer if you’re bringing new land into production. Plan ahead, and tarp all winter. Silage tarps warm the soil for early spring plantings, and also prevent soil moisture from evaporating.

Solarization uses clear plastic (old hoophouse plastic is ideal). In a summer hoophouse, solarization can be as quick as 24 hours, Andrew says. When we’ve done this, one of our goals was to kill nematodes and fungal diseases, not just weeds, so we waited a few weeks. Outdoors it takes several weeks. You can see when the weeds are dead. Bryan O’Hara poked a thermometer probe through solarization plastic and found a 50F degree (28C) difference between the outside air and the soil immediately under the plastic; a 10F (6C) difference at 1″ (2.5 cm) deep and little temperature gain lower than that. Solarization does not kill all the soil life!

The growers interviewed explain which methods they use and why, helping readers weigh the pros and cons for the various crops we are growing, and our resources, climate and soils. Andrew offers some pointers on which methods are likely to work best for which situations. Several farmers tell how they transitioned into organic no-till for various crops, for instance buckwheat, compost and Weed Guard Plus paper mulch for a garlic crop, followed by two crops of lettuce. Mossy Willow Farm in Australia has a designated area for direct-seeded crops, where they use sprinklers, and the tilther if needed. The rest of their farm (transplanted) uses drip irrigation, but the soil does get too clumpy for direct seeding, and is slower to improve.

Farmers also address the things that went wrong while they were learning (thin stands of cover crops, cover crops not dying, getting the timing wrong on seeding or roll-crimping, weed seeds blowing in from elsewhere). They describe equipment they found helpful (drop-spreaders to lay down even layers of woodchips or compost, landscape fabric, the stand-up bulb planter, Tilther, Jang seeder, paperpot transplanter, broadfork). They also address timing of cover crop sowing to avoid warm-season and cool-season weeds; extending the weed suppression period of cut or crimped cover crops by adding tree leaves; pre-irrigating before digging transplant holes; and many other tips to success. A strategy for tall crabgrass is to mow it down, cover with newspaper and compost. A border of comfrey plants all-round the garden does a great job of keeping grass out. You can quickly see how this book will pay for itself many times over!

No-till beds are ready for early spring crops, even in wet regions, if the beds are mulched overwinter. Because no-till builds soil upwards, it is a good technique for land that is very rocky or with shallow topsoil. Another advantage of no-till is that you can install fairly permanent irrigation (drip or sprinklers). And you can farm intensively on small areas without needing to cater to the turning radius of large machinery. Getting high productivity from small areas is becoming an essential factor to consider.

Potatoes are a soil disruptor, and can bring up new weed seeds, so it’s worth covering the beds as soon as the potatoes are harvested. At Four Winds Farm in New York State, they plant garlic in the fall after potatoes, then mulch over the top of the garlic with a thick layer of compost. In their bigger plan, they only plant garlic in every other bed (although composting all). The following spring they plant winter squash in the empty beds, which can take over all the space after the garlic is harvested.

As I read the interviews, I started to worry: were none of these farmers having a problem using such high amounts of compost? The first problem is making or buying the sorts of quantities they are using, but the second is a build-up of phosphorus, which we have experienced on our farm. Singing Frogs Farm has studied this, testing the water run-off in the ponds at the low-point of their land. The phosphorus stays in place in their system, it does not leach. Nor does the nitrogen. The soil biology sponges up the nutrients, the 3-8 crops they grow in a year absorb them. They don’t rely on compost for fertility, but now   use pelleted feather meal, calcium and rock dusts. Their compost use is 0.5″ (< 1 cm) per year, very different from the many farmers using much more.

Daniel Mays at Frith Farm in Maine believes cover crops provide a more active kind of organic matter, which is tailored to the soil. He is seeing better results than with compost. Roots in the Ground! Hedda Brorstrom, of Full Blossom Flower Farm, Sebastopol, CA is trending in the other direction. She points out that a lot of the compost for sale is made with lots of animal manures, which does send the phosphorus levels way up. Because growing cover crops was not working for her, she researched available composts carefully. High-carbon compost is a way to avoid sending the phosphorus levels up too much. She has used 4-8″ (10-20 cm) of compost per year.

Neversink Farm in New York’s Catskill Mountains point to intensive production (“the greenhouse mentality writ large”), 5 people working on 1.5 acres of permanent (not-raised) beds, and direct sales to customers, as factors in their success. As Conor Crickmore says proudly, “Our farming practices may be radical but they have resulted in our farm being one of the highest production farms per square foot in the country.” Close to $400,000 gross on 1.5 acres!

The collected wisdom and experience in The Organic No-Till Farming Revolution can save newer no-till farmers from a lot of frustration and wasted time, money and mental and emotional energy.