Root Crops in August

Root Crops in August

Misato Rose Winter Radish.
Photo Southern Exposure Seed Exchange
China Rose Winter Radish.   Monticello Shop

Root Crops to Plant in Central Virginia in August

Like July, August is not a good month for sowing many root crops in Virginia – it’s very hot. However, the daylight is getting shorter and so the hot part of the day is also getting shorter.  And the calendar is boxing us in. The month of August is when we establish crops that will feed us in the fall and winter.

Carrots:

On August 4, we sow our fall carrots, enough to store and feed us all winter. Twin Oaks can eat 30+ bags (50 lbs, 23 kg each) of carrots during the winter, so we try hard to grow a big crop of fall carrots. See Root Crops in May for more about sowing and growing carrots, including pre-emergence flame weeding.

Good irrigation is important for successful carrot growing in hot weather.
Photo Bridget Aleshire

Carrots do very poorly with competition, so try to grow them in a bed that had only light weeds. You can use the Stale Seedbed Technique, where the bed is prepared ahead of time, and one or more flushes of weeds are germinated and flamed or hoed off. Carrots do well on raised beds, because the soil stays loose and the roots can easily grow deep.

Some people bake old carrot seed to dilute the good new seed, to reduce the thinning work and the wasted seeds. Some people sow in single rows 8-10” (20-25cm) apart. Others sow in bands 2″ (5 cm) wide, at 8” (20cm) apart, with one length of drip-tape serving two bands in one 16-24″ (40-60 cm) bed.

Hard rain in the first 3 or 4 days after planting can dry to a crust that could prevent emergence. If you get heavy rain, irrigate for half an hour each day afterwards until the carrots emerge. Some people use shade cloth to help keep the soil surface moist.

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. The idea is to flame the beds the day before the carrots are due to emerge.

Table of days to germination of beets and carrots at various temperatures

Days to Germinate 50°F (10°C) 59°F (15°C) 68°F (20°C) 77°F (25°C) 86°F (30°C) 95°F (35°C)
Carrots 17.3 10.1 6.9 6.2 6.0 8.6
Beets 16.7 9.7 6.2 5.0 4.5 4.6

If we are unable to get our fall carrot sowing finished in early August, we sow them in late August. We try to avoid sowing in the middle of August when the hordes of baby grasshoppers emerge. If we have to sow in the middle of August, we use hoops and fine mesh ProtekNet, battened down well around the edges to keep the pests out. The hoops hold the netting up above the foliage, keeping it inaccessible to insects.

Beets

Beets can be tricky to germinate in hot weather, but to get a good storable-sized root, we need to get them established by 8/20 at the latest. (Our first frost date is 10/15 to give you an idea of when things cool down.) We get ready to sow on 8/1, but sometimes we wait for a cooler spell. I like the Cylindra beet. The shape is long (good for slicing), the skins come off easily, and the flavor is very sweet and the texture tender.

Young Cylindra beets.
Photo Wren Vile

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.  Either way, sow 1/2″-1″ (1-2.5 cm) deep, tamp the soil firmly so that the seed is in good contact with the soil and its life-saving water supply. Keep the row damp, by watering daily as needed for the 4-6 days they take to emerge. Beets prefer 50°F–85°F (10°C–29°C). Some people lay boards over the seeded rows but then you have to be sure to check frequently and remove the boards when the seedlings emerge. Other options include covering the beds with shadecloth on hoops, or making some other temporary screen to the south side.

Turnips:

I mentioned turnips in July as a crop to harvest. That was the spring-sown turnips. We sow our fall turnips 8/15 or up until 9/15 (our absolute latest). Turnips can be up the next day, even at 95°F (35°C). Most will be Purple Top White Globe for winter storage. Because of the high populations of harlequin bugs, and sometimes aphids or flea beetles, and cabbage caterpillars, we hoop and net all our fall brassicas. We like ProtekNet (for smaller amounts than a whole roll, try Johnnys)

Brassica transplants under ProtekNet. (I couldn’t find a photo with turnips) Photo Bridget Aleshire

Winter radish:

In central Virginia, we sow winter radish on August 4. They have no trouble germinating at high temperatures. We like to grow Misato Rose, Miyashige Daikon and Shunkyo Semi-Long.

China Rose winter radish.
Photo Southern Exposure Seed Exchange

Kohlrabi:

Early Purple Vienna and Early White Vienna can still be sown here in August. They take only 60 days from sowing to harvest. They can be direct sown or transplanted from flats or an outdoor nursery seedbed. Kohlrabi is hardy to maybe 15°F (-9.4°C). It doesn’t get that cold here before the beginning of November, so counting back 31 days in October, plus 30 in September, plus 31 in August – that’s 92 days already, more than enough. We can sow kohlrabi in early August and get a crop at the end of October.

Purple kohlrabi
Photo Small Farm Central

For fall brassica crops, we use an outdoor nursery seedbed and bare root transplants, because this fits best with our facilities and our style. Having the seedlings directly in the soil “drought-proofs” them to some extent; they can form deep roots and don’t dry out so fast. Other people might prefer to sow in flats.

We cover the beds with ProtekNet insect mesh on wire hoops until the plants are big enough to stand up for themselves against “pest bullying”. Overly thick rowcover or rowcover resting directly on the plants can make the seedlings more likely to die of fungal diseases in hot weather – good airflow is vital.

We aim to transplant most brassicas at four true leaves (3-4 weeks after sowing). In hot weather, use younger transplants than you would in spring, because larger plants can wilt from high transpiration losses. If we find ourselves transplanting older plants, we remove a couple of the older leaves to reduce these losses.

Fall radishes:

Easter Egg radish seedlings in early September.
Photo Pam Dawling

We direct sow small radishes from mid-August (best) to mid-September (latest). Our favorite is Easter Egg, a mix with a range of colors that don’t all mature on the same day, but feed us over a couple of weeks. They are less likely to get fibrous than Cherry Belle or Sparkler types.

Root Crops to Harvest in Central Virginia in August

Carrots:

I usually reckon on three months from sowing to harvest for carrots, but they can be faster in warm weather. See Root Crops in June for more on carrots. If you sowed carrots in May, they should be ready to harvest in August. Don’t delay or they will become woody in texture and soapy in flavor. I suppose they are still nutritious, so if this has happened to you, blend into soups or make flavorful stews.

Turnip thinnings:

A few weeks after sowing, you will need to thin your turnips. You can use the tiny thinnings as microgreens for salad, and the bigger ones (with marble-sized turnips attached) can be gently steamed or braised.

Potatoes being harvested.
Credit Kathryn Simmons

Potatoes:

Depending when you planted your potatoes, they could be ready from mid-June onwards. They take about 4 months to reach maturity, so during August, potatoes planted in April will become ready.

See Potato Harvesting and Root Crops in June for more on harvesting. For best storability, wait until two weeks after tops have died to harvest. During that time, the skins will toughen up and you’ll have fewer harvest injuries. Potatoes can bruise! They may look tough and inert, but they are living plant matter and should not be thrown or banged about. To test if potatoes are ready to store, dig up two potatoes and rub them together, or rub them firmly with your thumb. If the skins rub off, wait a couple of days before trying again. If the skins are strong, go ahead and harvest. see next weekk’s post for more on storing potatoes.

Other Root Crop Tasks in Central Virginia in August: sorting potatoes, thinning carrots and turnips

Sort potatoes

Sort potatoes two weeks after storing. Transfer the potatoes individually into clean crates, checking them for any dampness or softness. We triage (sort into three categories); those good to continue in storage, those fit only for the compost bin and anything we’re not sure about, but hope is not a total loss. We take these optimistically to our kitchen and plan to use them soon, if necessary cutting away bad portions. We find that this single sorting two weeks after putting the potatoes into storage can make all the difference. Most potatoes have “declared themselves” as fit or not by this point. Removing the rotting ones prevents the rot spreading. Often this is the only sorting we do. If you have time (or no bags of pasta in the pantry), you could aim to sort once a month until deep in the winter.

Sorting potatoes two weeks after harvest, to remove problems.
Photo Wren Vile

Ventilate the root cellar every few nights when it is coolest. Gradually get temperature down to 65°F (18°C). Try not to have temperature reversals. You don’t want to chill the potatoes yet – they are still breathing and need time to settle into dormancy.

Next week’s post will be devoted to storing potatoes successfully. It will be Part 5 of my Potatoes series. If you’re reading this in the southern hemisphere, you can use the Search box to find information of planting potatoes. Just add or subtract six months from my accounts.

Carrot thinning:

It is much easier to see the carrots, and they grow better if the first flush of weeds has been flamed off. Get to the initial thinning of carrots as soon as you can, spacing to about 1” (2.5 cm) apart, weeding at the same time. We usually have someone with good eyesight and hand-eye co-ordination hoe between the rows the day before the hand-weeding. If you are in an area with Carrot Rust Fly (Carrot Root Fly), remove all thinnings and broken foliage from the field, so you don’t lure the low-flying pest with the wonderful smell of the broken leaves. We do a second thinning, to 3” (8cm) at the stage when the baby carrots can be used for salads. If we get more weeds, we might do another round of weeding before harvesting the full size carrots. If carrots are spaced too widely, they will be more likely to split, and the overall yield will be reduced.

Carrot row thinned to one inch.
Photo Kathryn Simmons

Mowing:

Keep edges mowed, and any buckwheat cover crop not seeding, so that you don’t encourage grasshoppers.

Special Root Crop Topic for August in Central Virginia: Sowing and transplanting when soils are hot.

There are definitely some challenges to getting seeds germinated in hot weather. And a different set of challenges to transplanting (not so applicable to root crops, as most are direct-seeded.)

 Here are some tips to try:

  • Choose suitable varieties. Read the catalog descriptions carefully. Look for flavor, productivity, disease resistance and cold-hardiness as well as heat-resistance. The crops you sow now need to emerge in hot weather and keep growing into cold weather.
  • Consider direct-seeding crops rather than transplanting them. They can be more cold-tolerant, probably because there’s no damage to the taproot. And transplants can struggle to recover from transplanting when it’s very hot.
  • Good soil preparation is important. Avoid over-cultivating before planting, as this makes crusting more likely.
  • Water a day ahead of sowing or transplanting, to reduce the need to water copiously afterwards. Pre-water furrows for large-seeded crops (I can’t think of any root crops with large seeds, off the top of my head).
  • Plant seeds deeper than you would in spring, as the soil is already warm and you want to guard against the seeds drying out. In cold weather we are guarding against seed rotting in cold wet soil.
  • You could sprinkle sand, grass clippings, straw or sawdust lightly along the rows.
  • After sowing, watering should be shallow and frequent, using fresh-drawn cold water, not something from a hose in the sunshine. For close-planted small seeded crops, use overhead sprinklers. Chilled water, night watering, and even ice on top of the rows can help reduce soil temperatures as well as supplying vital moisture.
If using a nursery seed bed, you can put ice cubes on top of rows of seeds in hot weather to help cool the soil.
Photo Bell Oaks

Sowing when soils are hot

Check the germination requirements for your crop (see Sustainable Market Farming), and the expected number of days to emergence under your field conditions, and use a soil thermometer.

If the soil temperature is too high for good germination, cool a small part of the outdoors. You could use the shade from other plants, shadecloth, boards, or damp burlap bags. For crops you normally direct seed, consider cooling a small nursery bed for your seedlings and transplanting later.

If outdoors is too challengingly hot, start your seeds indoors. Put a sown flat in a plastic bag in your refrigerator or in a cool room. Try the basement floor, perhaps. Cover flats with wet newspapers until the seedlings emerge. You could use plug flats or soil blocks rather than open flats, to reduce transplant shock.

Soaking seeds – a help when temperatures are high and soils are dry.

The length of time to soak a seed depends on its size: bigger seeds can benefit from a longer soak. Soak large seeds like beans and peas overnight before planting. It helps them get all the water they need to absorb for the initial sprouting. After that the smaller amounts needed to emerge are more easily found. Don’t soak legumes so long that the seed coat splits, or they lose nutrients and may get attacked by fungi.

Smaller seeds may only need to soak for 1-2 hours. I suspect that when I’ve had failures with soaked beet seeds, I soaked them for too long and they suffocated from a shortage of oxygen. Small seeds that have been soaked tend to clump together, so after draining off as much water as possible, mix them with a dry material like uncooked corn grits, oatmeal or bran, or use coffee grounds or sand to make them easier to sow thinly.

If you are using a seeder, spread your soaked or sprouted seeds out in a tray for a while to dry the surfaces. Experiment on a small scale ahead of a big planting, to make sure your seeder doesn’t just grind the seeds up, or snap off any little sprouts.

Pre-sprouting seeds to plant

To pre-sprout seeds, first soak them in a jar, then drain off the remaining water and put them in a cool place. Rinse twice a day, draining off the water. Sprout the seed just until you see it has germinated. For most crops 0.2″ (5 mm) is enough. Seeds with long sprouts are hard to plant without snapping off the shoot. If your pre-sprouting has got ahead of the weather or the soil conditions, slow down growth by putting the seed in the refrigerator. If you have leftover soaked or pre-sprouted seeds, you can store them in the fridge while the others come up, and then use them to fill gaps.

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