Root Crops in March

We shovel many wheelbarrows full of compost to our raised beds every year.
Photo Wren Vile

Root Crops to Plant in Central Virginia in March

As soon as the soil is dry enough and not frozen, we spread compost on the raised beds we plan to plant in February and March, and till in the compost. We make ourselves a Spring Start-up Plan, so we know where to focus our energy when the weather gives us a chance.

Spring Start-up Plan

We aim to spread compost 4-6 weeks before planting, rototill 2-4 weeks before planting, and prep the bed a week or two before. This is more time than we allow later in the year, but in early spring it’s good to seize the opportunities that arise and not take the weather for granted.

This means in January we compost and till beds for spinach, turnips and our first carrots. In the first half of February we till the turnip beds and any beds of winter-killed oats cover crops that we will be planting soon. We compost the first lettuce bed, the kale and collard beds, and those for cabbage, beets, more carrots, senposai and peas (all have planting dates March 9 to 15). In the second half of February, we compost the third carrot bed and till the ones we already composted. In early March we till the third carrot bed.

A bed ready for tilling after mowing the cover crop and spreading compost.
Photo Pam Dawling

Once we get to March, day length has increased and temperatures are starting to climb. There is a noticeable increase in the rate of germination and growth (unlike for our February sowings, which are rooted in faith and optimism!) All being well with the weather (it’s extremely wet this year!), in early March, we direct sow turnips (3/6- 3/16), and radishes #1 (Cherry Belle or some other fast variety)

In mid-March, we can transplant kohlrabi. And we direct sow carrots #3 and beets. See below for more about beets. In late March, we direct sow our carrots #4, and more radishes and beets. We can sow kohlrabi if we have no transplants, and thin to 6” (15 cm) later.

Potatoes

A row of potato seed pieces ready to cover.
Photo by Wren Vile

We plant potatoes when the daffodils bloom, usually mid-March. Last year I wrote an extensive series of posts about growing potatoes.

See Planning to Grow Potatoes Again, the last part of a monthly series on growing potatoes, a dietary staple.

PART ONE: Planting potatoes (April)

PART TWO: Growing potatoes (May)

PART THREE: Potato pests and diseases (June)

PART FOUR: Harvesting potatoes (July)

PART FIVE: Storing potatoes (August)

PART SIX: Planning to grow potatoes again (September)

Beets

Detroit Dark Red beets in early June sunshine.
Photo Pam Dawling

Beets are workhorse root crops that thrive in mild weather, store well, and are popular traditional foods. They are crops that can provide high yields for the time invested.

Beets come in several types, round, top-shaped and long. The size and quality of the greens is a factor if you sell bunched beets with tops, or use the tops for greens. We like the 6” (15cm) long Cylindra/Formanova/Forono ones (55 days to maturity, OP). They are very tender and easy to cut into regular slices, for pickles or cooking. The skins come off easily, and the flavor is very sweet and the texture tender.

Among round ones we like Ace (50 days to maturity, F1 hybrid), and Detroit Dark Red (60d), a tender open-pollinated variety. Detroit Crimson Globe is said to maintain better flavor in hot weather than most others, which can develop off-flavors. Early Wonder Tall Top (48d), is also open-pollinated. Lutz Green Leaf (70d) is a big long-storage variety. There are also golden beets, white beets and candy-striped Chioggia beets, although in my experience, what they gain in appearance they lose in flavor and tenderness.

Beets seeds average 35,000 /lb. 2,200/oz, 80 seeds/gm. 1,285 seeds (2/3 oz, 18gm) sow 100’ (30m).  150’/oz, 2,300’/lb., 9 lbs/acre. 315,000 seeds/acre. Yield can be 40 lbs. (18kg) greens, 100 lbs. (45kg) roots/100’ (30m), or 14,000 lbs/acre, 2540 kg/ha.

Beets need a pH of 6.0-7.0, preferring 6.5-6.8.  They require abundant potassium, which can be supplied by woodash. Boron deficiency can show up in beets as internal browning, or dark dead tissue, as well as distorted leaf growth. It is most likely to occur in alkaline soils after long hot, dry spells. Beets can suffer from “zoning,” (white rings in the roots), if there are acute weather fluctuations.

Young Cylindra beets in early May.
Photo Pam Dawling

Sow beets whenever the soil is between 50°F (10°C) and 95°F (35°C), so long as you can keep the surface damp. With beets we do a single sowing in mid-March and more in early August. We are growing for fresh use, pickling and storage, but not bunch sales, so we don’t need to do frequent sowings. For a continuous supply of greens and baby beets, sow every 2 weeks from spring until 8 weeks before regular frosts usually occur, or about 10 weeks before a heavy freeze is expected.

We direct sow either dry beet seed, or some we have presoaked for 1-2 hours. Beet seed drowns easily: don’t use too much water or soak for too long.  Sow 0.5″(1.2cm) deep in spring, deeper in hot summers, but never more than an inch (2.5cm) deep. We sow an inch (2.5 cm) apart in single rows 8-10” (20-25cm) apart. Others sow in bands 2-4″ (5-10cm) wide, at about 15 seeds/ft (2cm apart), with bands 12-18″ (30-45cm) apart. As for carrots, avoid soil crusting.

It is important to get good soil contact for the corky seedballs, so tamp or roll the rows after seeding. Keep the rows damp, by watering as needed for the 5-17 days they take to emerge. Beet seeds are actually seed balls (clusters of seeds) so each one you plant will produce several seedlings right next to each other. “Singling” the beets is an important step, and they will benefit from hoeing, thinning and weeding. Beets deal with weed pressure and crowding a lot better than carrots do, so if you have to choose which to weed, the carrots win! We thin in stages, so that at the second thinning, the baby beets can be used as a crop.

Detroit Dark Red beets , harvested, washed and trimmed.
Photo Pam Dawling

For mature beets, allow each a minimum of 3” (7.5cm). The Cylindra beets can be left a bit closer, and will push themselves up out of the soil as they grow. Know and Grow Vegetables recommends establishing 5 plants per square foot (54 per square metre) for early beets. This translates to a final spacing of 4 x 7” (10 x 18cm). For maincrop beets, aim for 10-15 per square foot (107-161 per square metre.) For maximum total yields of small sized roots use a spacing of 1 x 12” (2.5 x 30cm).

This info about growing beets is excerpted from my book Sustainable Market Farming. See the book for more on pests and diseases, harvesting and storing, and seed saving.

In our climate, beets are one of the crops that can be sown in spring and again in early fall (actually August for beets here in central Virginia). See my August post Sowing beets, radishes and kale, transplanting cabbage.

See Root Crops in August for more about fall beets. Beets can be tricky to germinate in hot weather, but to get good storable-sized roots, we need to get them established by 8/20. (Two months before our average first frost.)

Root Crops to Harvest in Central Virginia in March

From storage, if we still have them, we can eat beets, carrots, celeriac, kohlrabi, parsnips, potatoes, rutabagas, sweet potatoes, and turnips.

As in January and February in central Virginia, there are no roots to harvest outdoors in March except parsnips, Jerusalem artichokes and horseradish. We do have horseradish, but not the others, but we don’t have a lot of demand for that.

We have had outdoor night temperatures of 12°F/-11°C and 11°F/-13°C. This winter we had some carrots outdoors over the winter. We harvested them and got 150 pounds from 400 row feet. Not a high yield but they do taste good! They are Danvers 126. The intended sowing date was August 14, but we didn’t get the seed in the ground until September 5.

A crate of overwintered Danvers 126 carrots

In the hoophouse our #4 radishes will get harvested during March. Our #5 radishes, sown 12/23, will then feed us until around April 7.

We still have some of our good size second hoophouse turnips until mid-March. We sowed those on October 25. The greens are a bit ragged now and less appetizing for cooking, although on cold rainy days, they make for more pleasant harvesting than any greens outdoors! Turnip greens (and Russian kale) are our last hoophouse greens to bolt, so we value them.  We need to harvest the turnips to make space to transplant our hoophouse tomatoes in mid-March.

Other Root Crop Tasks in Central Virginia in March

  • Green chit (pre-sprout) seed potatoes, see Planting potatoes .
  • Buy seed potatoes for June planting, and refrigerate them. Keep at 40-50°F (4.5-10°C) in the dark, until 6/1.
  •  Test and condition sweet potatoes for 2 to 4 weeks at 75-85°F (24-29°C), 95% humidity if you are planning to grow your own sweet potato slips.
Sweet potato sprouting slips.
Photo Pam Dawling

Special Root Crop Topic for March in Central Virginia: What makes vegetable crops bolt?

Green mizuna bolting in our hoophouse in mid April. Although the mizuna is bolting, the Scarlet Frills is hanging in there.
Photo Pam Dawling
  • Bolting is the term for plants going to seed. Rather than grow more leaves and bigger roots, the plants develop stems, skinnier and fewer leaves, then flower buds, flowers and seeds.
  •  The plants are switching their energy to survival of the species in the face of unsuitable conditions.
  •   When a plant starts to bolt, it is usually a sign to expect a poor harvest. It is also an indication that the plant will decline in terms of flavor. Lettuce become bitter. As long as you can harvest leaves or roots that are not too woody, you can eat bolting plants. But they do become too tough and inedible at some point.
  •  Crops inclined to bolt include arugula, basil, beets, brassicas (such as cabbage), carrots, celery, leeks, lettuce, onions, turnips and spinach.
  •  Bolting is initiated by plant hormones called gibberellins.
  •  Although bolting is usually seen on crops approaching maturity, it is initiated much earlier.
  •  It’s a complex business, understanding the various triggers to bolting.
  •  Stress factors, including changes in day length (usually an increase), high temperatures or low temperatures at particular stages in a plant’s growth cycle, plant size, plant type, root stress, and stresses such as insufficient water or minerals.
  • Increased day length: Bolting can happen when day length increases as summer approaches. This can be a problem if you planted your seeds too late in the spring. The extra hours of light trigger annual plants to run to seed.
  •  High soil temperatures: As soil temperatures increase in summer, plants are triggered to begin seed and flower production. This isn’t a problem late in the crop’s life, after bountiful harvests. But, when spring has unusually hot weather or if you plant crops too late into the growing season, your crop may bolt before any harvests. Cool weather crops like lettuce and spinach will bolt in spells of hot dry weather.
  • Cold temperatures: A sudden cold snap in spring can signal to biennials (such as onions, leeks, beets and carrots) that “winter” has happened and it’s time to develop seeds for the next season. If you start these crops too early in the calendar year, you risk exposing young plants to cold weather, priming the plants to develop flower stems as soon as the weather warms up again. 
  •  Plant size:
  •  Annual plants grow from seed, flower and set seed all in one year. That can be spring to winter or fall to summer. Annual crops are sensitive to daylength, and will start making flowers as the daylength (and temperature) increase. When an annual plant bolts, it’s the beginning of the end.
  • Biennial plants (onions, leeks, carrots, beets, and chard) grow big the first year, then seed the second year. They can initiate flowers in the first yea, due to unsettled weather early in the season. Bolting usually occurs after a prolonged cold spell, often during an immature stage. Cold nights, hot days and late frosts may also contribute to premature flowering.
  • Root stress: Bolting caused by root stress typically happens when you disturb a plant’s root system by transplanting, or if your plant runs out of growing space in a container that’s too small.
  • Stresses such as insufficient minerals or water: Healthy soil with plenty of nutrients and balanced moisture levels will encourage quick growth. Every grower should aim for this balance, especially those in hotter climates where it’s a race to plant leafy salads, cooking greens and root crops before the hot weather fights against you.

Collards bolting in late March.
Photo Pam Dawling

Next week I will provide information on avoiding, preventing and postponing bolting.

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