Root Crops in June

Early September photo of mulched June-planted potatoes.
Photo Kathryn Simmons

Root Crops to Plant in Central Virginia in June

Potatoes: Yes, it is OK to plant potatoes in June, up until late June. Count back from your first frost date the 80-100 days or whatever your chosen variety needs to mature. See my post on planting potatoes. We buy our seed potatoes for the June planting in April, before local suppliers sell out of spring stocks. We store them in our walk-in cooler until two weeks before the planting date. I recommend some special techniques for summer potato planting. See the Other Root Crops Tasks section below for more details. An advantage of summer planting is that the harvested crop need only be stored from October or November, not over the hotter months.

Sweet potatoes: It’s still OK to plant sweet potatoes in June in central Virginia, and if you live in a colder climate, you probably wouldn’t even try to plant in May. It is best if the soil temperature is 65°F (18°C) for four consecutive days before planting.  See my post on sweet potato planting

Carrots: We direct sow our seventh bed of carrots in mid-June. It can be hot and the challenge is to keep the soil damp. Unlike some other crops (lettuce and spinach come to mind), carrot seed will germinate just fine at high temperatures. Shadecloth can help keep the soil damp, or you can just water a lot. You won’t need to do daily watering for long: maybe only 4 days. See Root Crops in May.

We only sow in June and July if we really need carrots, as hot weather impairs the flavor. Our hope is always that we will have grown enough between February and May to last till late October, and have bags in storage in the walk-in cooler. Sow carrots whenever the soil is below 95°F (35°C), so long as you can keep the surface damp. In summer we flame 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.

See the Special Topic below for more on growing carrots.

Warmer climates with later frost dates than central Virginia: you may still be able to plant crops we gave up on in May.

Colder climates: you may need to sow rutabagas, which we don’t need to do till July.

Root Crops to Harvest in Central Virginia in June

Cylindra Beets.
Credit Southern Exposure Seed Exchange

Beets: We like Cylindra best (55 days to maturity, OP). Detroit Crimson Globe is said to maintain better flavor in hot weather than most others, which can develop off-flavors. Remember as you harvest beets to check the leaves, as possible cooking greens too.

Beet leaf with Cercospora leaf spot.
Photo Purdue vegcropshotline.org

Later in the summer ours develop spotty holes from Cercospora Leaf Spot, and become unappetizing, but in early June they are usually fine. We like to clear all our spring beets by the end of June.

Store beets at 32°F (0°C) and 95% humidity. Trimmed beets keep well in perforated plastic bags under refrigeration. We have “rediscovered” stored bagged beets at the back of the refrigerator 9 months or so later and they were in fine condition.

There are also non-electric storage methods for roots, but these mostly rely on cool soil and cool air, so I’ll write about those when we get to fall. If you have a root cellar with a good temperature, you can use that. I have a chapter on root cellars in Sustainable Market Farming.

Carrots: Our second carrots (sown in late February) and third (sown in mid-March) will be ready to harvest in June. Possibly also our fourth sowing (late March), by the end of June. Don’t leave them in the ground too long, or they will get fibrous and woody. No fun!

Fennel bulbs: if you planted those in spring, they will be ready in June in central Virginia. If you didn’t grow this, consider it for fall, when it is easier to grow it without danger of it bolting. I wrote about fennel as a hoophouse crop in The Year-Round Hoophouse.

Kohlrabi: In our zone 7 climate, kohlrabi, like other brassicas, can be grown in spring or fall. So you can buy seed now and plan for kohlrabi in October, November, or into the winter if you store it. In spring we harvest kohlrabi from May 10 to June 30, when they reach 2-3” (5-7.5 cm) in diameter (or even up to softball size). The base of the globe can be quite fibrous, 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 root. We definitely need to dig all our spring kohlrabi by the end of June at the latest, or they get too woody. Unlike carrots and turnips, fennel and kohlrabi can successfully be transplanted.

Potato harvest.
Photo by Nina Gentle

Potatoes: In mid-June we can start harvesting spring-planted potatoes as delicious “new” potatoes. Check under a plant to see how big the potatoes are. If they are big enough and you aren’t worried about reducing later final yields by starting early, go ahead and dig some. It doesn’t matter that the tops haven’t died. These new potatoes will have shreds of thin skin, not the firm skins needed for potatoes to be storable, so just dig them as you need them. If this is your first year growing potatoes, you will be amazed at how good they taste boiled with a sprig of mint. So much tastier than store-bought!

Turnips:  They are among the fastest growing crops other than leafy greens. We harvest our spring turnips gradually, pulling the biggest and letting the rest grow bigger. By the end of June, though, we need to have them all up and if we have plenty, we store some in perforated plastic bags in the walk-in cooler, until mid-July. Turnips will keep for about 4 months at temperatures close to freezing and humidity of 90-95%. Higher humidity will make them rot.

Early Purple Top Milan turnip in late May.
Photo Pam Dawling

Other Root Crops Tasks in Central Virginia in June: Summer Potatoes

In early June, in preparation for mid-June planting, we chit (pre-sprout) our seed potatoes for two weeks in trays in the light. Unlike chitting in February and march, the potatoes don’t need supplemental heat at this time of year. The method is the same as I described in my post Planting Potatoes. Let all the sprouts grow. For warm-weather planting, one sprout per seed piece is usually sufficient – the chance of frost is over, and “spare” shoots are not needed. Tubers with many sprouts can be cut into many seed pieces, which can save money. See the Planting Potatoes post for details on Cutting Potato Seed Pieces.

In warm conditions, deeper planting, hilling and thick organic mulches all help keep the plants cooler, as does irrigation. To help keep the soil cool while the potatoes are growing through the heat of July, August and September, we mulch with spoiled hay. (Straw would be nice, but this is not a grain-growing area). We bale our hay in the big round bales, and we have almost a quarter acre of summer potatoes to cover, so it is by far easier for us to unroll the bales before the potato shoots emerge from the soil. To lay the mulch by hand around the potato plants after they come up would take way too much work on our scale. Home gardeners may use loose mulch and tuck it in around the plants later.

So, in order to mulch the day after planting, we cover the seed pieces with soil, using the tractor and the hiller. (When we used our BCS tiller for this, we simply tilled between the rows, which leveled the field and covered the potatoes well enough). Then we hill, and unroll round bales of spoiled hay immediately, or the next day. Potatoes emerge quickly in warm weather! Hilling is tricky without any visible signs of where the potato pieces are. We have sometimes used stakes and ropes to mark the rows, or else flags at the ends of the rows, and crossed fingers as we drive the tractor and ridger down the field.

Unrolling hay bales is close to an Olympic team sport! We line up the bales (using a tractor and hay spike or forks) shoulder to shoulder at the uphill end of the patch. Our land is almost flat, but even a slight slope makes a noticeable difference when pushing a hay bale, so do start at the top end! Next we study the pattern of the grass stems in the ends of the bale, and if needed twizzle it round 180 degrees on the ground, so that it will unroll itself when pushed. We cut and remove the twine, then two or three people start it rolling. Once it’s going, each bale has two people unrolling it, and eventually it gets small enough for one person to handle and the other can go back to the top and help start another bale. We try not to walk on the hills and we try to lay out the hay like wall-to-wall carpeting, without gaps.

Newly mulched potato patch in June.
Photo Pam Dawling

About 16 days after planting, in late June, we do a walk-through, one person per row evening out the mulch, and freeing trapped potato shoots. Everywhere we expect to see a potato but don’t, we part the mulch carefully, seeking pale flattened shoot. If we find one, we rearrange the mulch a little, so that the shoot is exposed to the light, but the soil is not. It’s not necessary to expose the whole shoot – even a little bit of stem is enough for the plant to reorient itself and be fine.

Later in the season we’ll need to weed the potatoes. I haven’t been mentioning it, but weeding is important for all crops, especially direct-seeded crops.

Special Root Crop Topic for June in Central Virginia: Carrot Types

I wrote quite a bit about sowing carrots, in the Root Crops in May blog post

These days there are many fancy colored carrots, but my preferences all lie with bright orange carrots, rich in beta carotene. We have tried growing a few white, yellow and purple varieties, but frankly I found them all very disappointing, as far as flavor and succulence. They tended to be scrawny! All carrots sweeten up when days are warm and nights cool.

Carrots come in five different carrot types based on their shape and size. The factors influencing your choice will be soil type, climate, market, and harvest time and method.

  1. Danvers are a long, thick-rooted cylindrical shape tapering to a point. They often have a yellowish core. The leaves and taproot are both longer than Chantenay types. They are suited to high production of bulk carrots and widely used in processing. They store well. They are more tolerant to poor soil, but grow best in deep, sandy loam. Making raised beds helps.

Varieties: Danvers (OP), Healthmaster (F1), Danvers Half Long (OP), Danvers 126 (OP)
Season: spring to fall. Summer in cool climates
Days to Maturity: 70-80 in spring, 80-110 in the fall

In central Virginia, zone 7, on a sandy clay loam, we grow Danvers 126, a sturdy open pollinated variety.

Danvers Half Long carrot
Photo Southern Exposure Seed Exchange
  1. Nantes are medium-length, straight, cylindrical roots 5-7” (13-17 cm) long with blunt tips and sparse foliage. A very quick growing variety. Nantes types have sweet, juicy, tender, crisp, almost red flesh; but only limited storage potential, and they are somewhat brittle. They contain few terpenoids, the volatile flavor compounds we think of as “carroty”. When poorly grown, they can be watery and bland. Nantes do best inloose, sandy soil or raised beds enriched with organic matter

Varieties: Early Nantes (OP), Scarlet Nantes (F1), Bolero (F1), Mokum (F1), Napoli (F1)
Season: spring to fall; summer if not too hot
Days to Maturity: 55-70 in spring, 60-75 in fall

We have grown the 75-day Bolero, a high-yielding carrot that stays sweet even in storage. 6-7” (15-18cm) long, with a 1 ½” (4cm) crown. It looks a bit prettier, and has slightly better flavor than Danvers, but ultimately we decided the extra cost of the seed was not worth it to us. The resistance to Alternaria or Cercospora found in Bolero has been important for our fall crop.

Scarlet Nantes carrot.
Photo Southern Exposure Seed Exchange
  1. Imperator –Most commercial growers produce this type. They are similar looking to Danvers, but bigger: longer, thicker in width, with stocky shoulders and strong fast-growing tops. They store very well. They perform best in deeply worked sandy loam soil. In rougher soils, they develop a slightly fibrous texture. Imperator types contain more terpenoids, and can be prone to bitterness if something goes wrong. Many hybrid varieties are a cross between Nantes and Imperator types.

Varieties: Sugarsnax (F1), Autumn King (OP)
Season: spring to summer in cool climates, or summer to fall
Days to Maturity: 55-100 in spring, 80-110 in fall

I have grown Autumn king in England and it was a very reliable variety.

Imperator carrots.
Photo Southern Exposure Seed Exchange
  1. Chantenay:short and broad conical roots with rounded tips, 6-7” (15-17 cm) long. Very vigorous top growth. Rich, sweet flavor. Chantenay store extremely well. They are the best type to plant in shallow, rocky or heavy clay soil due to their shape. Of course they also do well in better soils! These are a great choice for those gardening in containers. It is important to harvest at the appropriate length because they become woody and poorly flavored if harvested too big.
Red-Core Chantenay carrot.
Photo Southern Exposure Seed Exchange

Varieties: Red Cored Chantenay (OP), Kuttiger (white, OP), Kuroda (OP) Hercules (F1), Carson (F1)
Season: spring to early summer, midsummer to late fall
Days to Maturity: 55-70 in spring; 70-110 in fall

I have grown Red Cored Chantenay (65 days), a blocky variety with a blunt tip, 5″ (13 cm) long and 2″ (5 cm) at the shoulder. It resists splitting. The flavor of Chantenay types has been described as “parsley-like”. Kuroda types have a drier, creamier flavor. They are tolerant to Alternaria.

Heavy yield of Oxheart carrots.
Photo Southern Exposure Seed Exchange

In the past, before the soil here had been improved, we had to grow shorter carrots, as the long ones would break in the tight soil. Most of the varieties recommended for clay soils are small, as well as short. Nearby at Southern Exposure Seed Exchange, they have had astounding success with Oxheart (90 days, OP) a large, squat, chubby Chantenay type, with shoulders reaching 5″ (13 cm) across and 3-4″ (7-10 cm) long with a full carrot flavor.

  1. Miniature: round, cylindrical or tapered roots less than 5” (13 cm) long; crisp texture and frequently quite sweet This grouping includes carrot varieties that are shaped like radishes and miniature regular-carrot shaped ones. They work extremely well in containers due to their short taproot; They will grow in any fertile soil that drains well They have only limited storage potential.

Varieties: Thumbelina (OP), Little Finger (OP), Parmex (OP), Atlas (OP), Babette (OP), Romeo (OP), Paris Market (OP).
Season: spring to early summer, late summer to fall
Days to Maturity: 50-60 in spring, 60-70 in fall

Atlas carrots.
Photo Johnny’s Selected Seeds

Johnny’s has a pictorial comparison of some varieties on their website, under Growers’ Library/Vegetables at for maincrop and storage carrot varieties, the tiny round Atlas, Romance, Hercules, Bolero, Nectar and the long slender Sugarsnax; and  for early varieties, small Adelaide, Yaya, Mokum and Napoli.

Growing Potatoes

Potato plant emerging in spring.
Photo Kathryn Simmons

This is the second part of a monthly series on potatoes. Last month I talked about Planting potatoes. Now they are in the ground, we turn our attention to growing healthy plants and doing all we can to maximize the yield.

Frosted potato plants May 10., after two nights at 30F and 29F. I hope this didn’t happen to you! If you know a frost is coming, try to get the potatoes hilled, which protects more of the stem and leaves under the soil. This increases the likelihood the plants will be able to grow back.
Photo Pam Dawling

Potato development stages and crop requirements

  1. First the plant produces roots, stems and leaves. This vegetative state lasts 30–70 days. Bigger plants have more yield potential, so the goal for this stage is to produce robust large plants. Vegetative (leafy) growth of potatoes is favored by warm, 80°F (27°C) moist weather, but tuber growth is favored by cooler soil conditions of 60°F–70°F (15.5°C–21°C). This combination can be achieved either by planting in spring, when the soil temperature lags behind increasing air temperatures and is still cool enough for tuber formation, or by adding organic mulches to keep the soil cool if planting in early summer.
  2. Tuber formation (a two-week process) and branching of the stems comes next. All the tubers (potatoes!) that will grow on that plant are formed in those two weeks. The number of tubers produced per plant depends on hours of daylight, temperature and available water in that short period of tuber initiation. Watering stimulates the production of more tubers. 5 gal/yd2 (22.8 l/m2) is a good amount to supply when tuber formation begins. Short day length is optimal, with a night temperature of 54°F (12°C). If temperatures at night are 68°F (20°C), initiation will be reduced; and at 84°F (29°C), will be inhibited. High nitrogen also inhibits initiation. During this stage, leaf growth continues. Flowering can happen too, but it’s not essential, so don’t worry if you get few or no flowers. Hilling adds soil to the stems, encouraging stem growth and providing sites for tubers to form.
  3. Third, the tubers grow larger, but don’t increase in number. When the leaves start to turn pale, the plant has finished its leaf-growing stage and will be putting energy into sizing up the tubers under the ground. Adequate water and nutrients are important during this critical stage which lasts until the plant reaches maturity for that variety, up to 90 days. Try to ensure at least one inch (2.5 cm) of water per week, up until two weeks before harvest. Avoid very uneven watering, or overwatering, as hollow heart could result. The size of the tubers depends on various growing conditions. Two or three weeks after flowers appear (if they do), the baby potatoes will be 1–1.6″ (2.5–4 cm) across. The best temperature is around 65°F (18°C), and I’ve read that potato size decreases by 4% for every Fahrenheit degree (7% per Celsius degree) above the optimal. Spacing is another factor — we got large potatoes one summer because we had poor emergence and therefore wide spacing! The heat of the summer didn’t stop them.
Three flat-tined potato forks to the left, four round-tined digging forks to the right. Flat tines do less damage, usually.
Pam Dawling

Potatoes dug during this tuber-sizing-up period will be “new” potatoes, and not have the thick skins necessary for storage. If you dig your potatoes during this stage (or “snitch” some, leaving the rest of the plant growing), you will be happy short-term, but your final total yield will be less than if you grew all the tubers to full size. If you planned for this, and grew plenty, you will be happy now, and happy later!

  1. Finally, the tops naturally yellow and die. The skins of the tubers thicken, which makes them suitable for storage. No more growth is possible. Sometimes there are reasons to terminate potato growth early – see Early Harvest below for more about this.

Hilling potatoes

Start hilling (pulling soil up over the plants in a ridge) when the plants are 6” (15 cm) tall. Hill again two or three weeks later and two more weeks after that, if the plant canopy has not already closed over, making access impossible. Hilling also provides an opportunity for dealing with weeds, so if possible do this task in sunny breezy weather which won’t let the weeds re-root.

Rows of potatoes after hilling.
Photo Wren VIle

On a small scale, use a rake or standard hoe to pull soil up from the side of the row opposite to where you are standing. If you are sharing the job, one person can work each side of the row at the same time. If you are alone, turn round and work back when you get to the end of the row. Don’t be tempted to twist your arms around and move the soil up the side nearest you. You will damage your body by this distortion of your spine and shoulders!

At the next scale up, use a rototiller with a hilling attachment, or perhaps a wheel hoe with a hiller, if your soil and stamina allows. We have used a semi-manual planting method, making single furrows with our BCS walk-behind tiller, planting by hand in the furrows, then using the tiller again to cover the seed pieces and hill. Nowadays we use a tractor-mounted furrower that can make two furrows in each pass, and disks turned inwards in pairs to ridge the soil.

Alternatives to hilling potatoes

If you can’t hill, you can increase the effective depth of planting by covering the rows with thick straw or hay mulch. This is easiest to do immediately after planting, before the plants emerge. We don’t mulch our spring-planted potatoes because we want the soil to warm up some from its winter temperatures.

Potato plant emerging through hay mulch in early July.
Photo Pam Dawling

When we plant in June, we cover the seed pieces, then hill, then unroll round bales of spoiled hay immediately, like wall-to-wall carpeting. We choose this method to help keep the soil cooler through the summer. In warm conditions, deeper planting, hilling and thick organic mulches all help keep the plants cooler, as does irrigation.

Weed control for potatoes

Potatoes are sometimes said to be a “cleaning” crop, as if they did the weeding themselves. Not so! Any cleaning that takes place is a result of cultivation. As with many plants, the initial growth stage is the most critical for weed control. Hilling in sunny weather can deal with lots of weeds in a timely way, especially if the machine work is followed up by the crew passing through the field hoeing. Organic mulches also reduce weeds. Potatoes later in life produce a closed canopy that discourages more weeds from growing until the tops start to die. Mary Peet reports that potato yields were decreased 19% by a single red root pigweed per meter of row left in place for the entire season.

Flame weeding can be used for potato plants while they are small, as well (as for carrots and beets before emergence as we see here).
Photo Brittany Lewis

In wet weather it can be impossible to hill when you’d like to, and this is where flaming can save the day. Flaming is not an alternative to hilling, but it can be a way to buy time and deal with rampant weeds if the soil is too wet to hill. Potatoes may be flamed at 6″–12″ (15–30 cm) tall. Beyond that, flaming is not recommended. See ATTRA for more on flame weeding. Flaming when the potatoes are less than 8” (20 cm) tall is also an effective control measure for Colorado potato beetles (More on pests next month). Choose a warm sunny day when the pests are at the top of the plants. Flaming can kill 90% of the adults and 30% of the egg masses, according to ATTRA.

Early harvest of potatoes

Sometimes there are reasons to terminate potato growth early. If you need storable potatoes, cut, flame or mow the tops of the plants, and wait two weeks for the skins to thicken up. To test for storability, 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. You might do this if you have a fast crop turnaround after spring-planted potatoes, such as we used to do when following our spring potatoes with our fall cabbage and broccoli. Another time I’ve brought potatoes to a rapid end was in England, when we got Late Blight. We cut and removed the diseased tops (so no spores went down into the soil), and were able to salvage the potatoes two or so weeks later. Back then, the recommendation was to burn the green tops. This would probably not be recommended these days. It made for a smoky fire we kept going for several days. Terrible air pollution!

For the earliest possible crop in a dry climate (but not the highest yield), plant “old” seed (ones with lots of hairy sprouts) in early spring, hold off on watering until the tubers are marble size, then give a single good watering at 5 gal/yd2 (22.8 l/m2).

While it’s tempting to dig up potatoes early, the yields will be higher if you wait till the tops die.
Photo Kathryn Simmons

Next month I will write about potato pests and diseases.