Alliums for November: Plant garlic, sow onions in a hoophouse, eat leeks

Tadorna winter leeks in October.
Photo Pam Dawling

Cold-Tolerance of Alliums

Alliums are more cold-tolerant than most people believe. Here are my observations of killing temperatures for outdoor crops. Note that crops often survive night-time lows in the hoophouse that would have killed them outdoors.

  • 12°F (−11°C): garlic tops if fairly large, most fall or summer varieties of leeks (Lincoln,King Richard), large tops of potato onions
  • 10°F (−12°C) some leeks (American Flag aka Musselburgh and Scottish Flag, Jaune du Poiteau)
  • 5°F (−15°C): garlic tops if still small, some leeks (Bulgarian Giant, Laura, Tadorna, Bandit), some bulb onions, potato onions and other multiplier onions
  • 0°F (−18°C): chives, garlic, a few leeks (Alaska, Durabel); some bulb onions, yellowpotato onions, some onion scallions (Evergreen Hardy White, White Lisbon), Walla Walla onions sown in late summer (with rowcover for winter)

Planting Garlic

Planting garlic.
Photo Brittany Lewis

You can see my garlic slideshow for more info. I was surprised to find I haven’t written much in my blog about planting garlic, so here goes! See the alliums chapter in Sustainable Market Farming for more on types, varieties, and garlic genetics. The information here comes form that chapter.

When to Plant Garlic

Plant when the soil temperature at 4″ (10 cm) deep is 50°F (10°C) at 9 am. If the fall is unusually warm, wait a week. Instructions from Texas A&M say less than 85°F (29°C) at 2″ (5 cm) deep. We plant in early November. In New Hampshire, mid-October is the time. The guideline for areas with cold winters is 2-3 weeks after the first frost but before the ground freezes solid for the winter. In Michigan, planting time is 6 weeks prior to the ground freezing, giving enough time for root growth only, to avoid freezing the leaves. In California, garlic can be planted in January or February.

Both hardneck and softneck garlic do best when planted in the fall, though softneck garlic may also be planted in the very early spring if you have to (with reduced yields). If you miss the window for fall planting, ensure that your seed garlic gets 40 days at or below 40°F (4.5°C) in storage before spring planting, or the lack of vernalization will mean the bulbs will not differentiate (divide into separate cloves).

Garlic shoots emerging from the mulch a few weeks after November planting. Photo Twin Oaks Community

Garlic roots will grow whenever the ground is not frozen, and the tops will grow whenever the temperature is above 40°F (4.5°C). In colder areas the goal is to get the garlic to grow roots before the big freeze-up arrives, but not to make top growth until after the worst of the weather. In warmer areas, the goal is to get enough top growth in fall to get off to a roaring start in the spring, but not so much top growth that the leaves cannot endure the winter. If garlic gets frozen back to the ground in the winter, it can regrow and be fine. If it dies back twice in the winter, the yield will be lower than it might have been if you had been luckier with the weather. When properly planted, it can withstand winter lows of –30°F (–35°C). If planted too early, too much tender top growth happens before winter. If planted too late, there will be inadequate root growth before the winter, and a lower survival rate as well as smaller bulbs.

How Much Garlic to Plant

A yield ratio of 1:6 or 7 seems typical, and makes complete sense when you consider you are planting one clove to get a bulb of 6–7 cloves. Divide the amount you intend to produce by six to figure out how much to plant. For large areas 750–1,000 lbs/ac (842–1,122 kg/ha) are needed for plantings in double rows, 3″–4″ in-row (7.5–10 cm), beds 39″ (1 m) apart. For single rows, 8 lbs (3.6 kg) of hardneck or 4 lbs (1.8 kg) of softneck plants about 100′ (30 m). In the US, one person eats 3–9 lbs (1.4–4.2 kg) per year.

Popping garlic cloves in preparation for planting
Photo  Southern Exposure Seed Exchange

Popping Garlic Cloves for Planting

The garlic for planting should be taken apart into separate cloves 0–7 days before planting. We are doing this on November 7, along with our crop review meeting when the crew meets to make notes on the past season. This task is a good group activity. Twist off the outer skins and pull the bulb apart, trying not to break the basal plate of the cloves (the part the roots grow from), as that makes them unusable for planting. With hardneck garlic, the remainder of the stem acts as a handy lever for separating the cloves. We sort as we go, putting good size cloves in big buckets, damaged cloves in kitchen buckets, tiny cloves in tiny buckets and outer skins and reject cloves in compost buckets. The tiny cloves get planted for garlic scallions. Don’t worry if some skin comes off the cloves — they will still grow successfully. Cloves for planting should be from large (but not giant) bulbs and be in good condition.

Click the link to read about hot water treatment for seed garlic at WeeBee Farms. 

Pre-plant Seed Garlic Treatments

Many of us do nothing special with the cloves before planting, but if you have pest and disease problems, use pre-plant soaking treatments, usually done the night before planting. Some growers find they get better yields from treated cloves even if no problem was obvious.

To eradicate stem and bulb (bloat) nematode (Ditylenchus dipsaci), soak the separated cloves for thirty minutes in 100°F (37.7°C) water containing 0.1% surfactant (soap). Or soak for twenty minutes in the same strength solution at 120°F (48.5°C), then cool in plain water for 10-20 minutes.

Allow to dry for 2 hours at 100°F (37.7°C) or plant immediately. Anytime your garlic grows poorly and you can’t tell why, send a sample with the soil it’s growing in to your Extension Service to be tested for nematodes. Mites can eat the skins of the cloves, survive the winter and multiply all spring long, seriously damaging or even killing your crop. To kill mites (which hide between the wrappers) before planting, separate the bulbs into cloves and soak them overnight (up to 16 hours) in water.

Possible additions to the water include one heaping tablespoon of baking soda and one tablespoon of liquid seaweed per gallon (around 8 ml baking soda and 4 ml liquid seaweed per liter). Just before planting, drain the cloves and cover them in rubbing alcohol for three to five minutes, long enough for the alcohol to penetrate the clove covers and kill any mites inside. Then plant immediately. The long soaking will loosen the clove skins so that the alcohol can penetrate. Mite-infested garlic soaked like this does much better than unsoaked infested garlic. The solution used to kill mites can also be used to kill various fungal infections. The cloves need only fifteen to thirty minutes soaking.

In trials comparing treated and untreated cloves, treated cloves were larger and healthier than untreated ones. Fusarium levels can be kept down by adding wood ashes when planting and then possibly dusting the beds with more ashes over the winter (use moderation — don’t add so much that you make the soil alkaline). Or you could soak the cloves in a 10% bleach solution, then roll them in wood ash (wear gloves for handling ashy cloves). The wood ash soaks up the dampness of the bleach and provides a source of potassium. This information came from the Garlic Seed Foundation. Join GSF to find out all the details!

Other November Allium Planting

Plant shallot bulbs before the end of November and medium-sized potato onions (1.5″ – 2″, 4-5 cm) at the end of November or early December in zone 7. Finish dividing and replanting perennial leeks and Egyptian walking onions this month

Young onion plant in March.
Photo Kathryn Simmons

Special Allium Topic for November: Sow Bulbing Onions in the Hoophouse

We developed a system of growing onion starts in our hoophouse over the winter and transplanting them bare-root outdoors in very early March. I wrote about choosing onion varieties for your latitude last month. There I explained that to grow big onions we need to have large transplants on March 1, so we can have big vegetative plants before bulbing is triggered by the daylength.

The method involves making two sowings of bulbing onions, each enough for the whole planting. This provides insurance in case one date turns out better than the other. Then we follow this up with a partial third sowing to make up numbers of any varieties that didn’t germinate well. We make our first sowing November 10, our second November 20, and a third on December 5 as a back-up in case of problems. Our formula is: divide the number of onion plants wanted by 20, to give minimum length of row to sow, in feet. And sow this amount twice, 10 days apart. The onions will be planted out at 4″ (10 cm) apart. We add 20% to provide some slack. For a final row of 100′ (30.5 m), we’d need 100′ × 3 per foot × 1.2 (adding 20%) plants. 360 plants. We sow 3 seeds per inch (approx. 1 cm apart), 36 per foot (30 cm). At this sowing rate, we need 120″, or 10′ (3 m).

See The Year-Round Hoophouse for more on growing onions this way. If we find ourselves with extra onion plants in March, we usually re-categorize them as scallions. But we have also transplanted them in early March in a single row along the south edge of hoophouse beds, for an early crop. We got good onions but they dwarfed the pepper plants behind them. Maybe planting them on the north side of the bed is better?

Trimming roots from a leek in December.
Photo Pam Dawling

Storing Leeks

I wrote about how to dig up leeks last month. In zone 7 we leave our leeks in the ground till we need them, being sure to harvest the less hardy Lincoln and King Richard first. We use a walk-in cooler for short term storage (up to a week) and keep the root ends in water. Leeks are best stored at 33°F (0.5°C) and 65% relative humidity. In colder zones, leeks can be harvested and stored in a root cellar or basement. This is helpful in areas where the ground freezes solid for weeks on end. You can store leeks with the roots packed in soil, shoulder to shoulder in a crate or box in a root cellar, where they will keep for six weeks. They can be stored in plastic bags for two to three months at the right temperature, or frozen. Another possibility is to leave them in the garden, mulched with a foot (30 cm) of straw or hay as well as rowcover, if temperatures are below 10°F (–12°C). Our winter temperatures fluctuate a lot, so covering in-ground crops with mulch doesn’t work well for us.

Winter radishes, planting garlic.

Our main task this week has been planting garlic, both hardneck and softneck. As we separated the cloves for planting, we put all the tiny cloves (which wouldn’t grow big bulbs) into small buckets. We use these to grow garlic scallions. Planting them is next on our list.

Garlic scallions are small whole garlic plants, pulled and bunched in the spring like onion scallions. They are chopped and cooked in stir-fries and other dishes. They are mostly green leaves at that point, although the remains of the clove can also be eaten. Hard-core garlic lovers eat them raw like onion scallions. They provide an attractive early spring crop.

To grow garlic scallions,  plant small cloves close together in furrows, simply dropping them in almost shoulder to shoulder, any way up that they fall. (If you’ve just finished a large planting of main-crop garlic, you’ll probably be too tired to fuss with them anyway!) Close the furrow and mulch over the top with spoiled hay or straw.

A healthy patch of garlic scallions in spring
Photo credit Kathryn Simmons

You could plant these next to your main garlic patch, or in a part of the garden that’s easily accessible for harvest in spring. Or you could plant your regular garlic patch with cloves at half the usual spacing and pull out every other one early. Think about quantities, though. If we double planted, we’d have over 7000 scallions, far more than we could use. The danger with double planting is stunting the size of your main crop by not thinning out the ones intended for scallions soon enough. We plant our small cloves for scallions at one edge of the garden, and as we harvest, we use the weed-free area revealed to sow the lettuce seedlings for that week.

With a last frost date of 20-30 April, we harvest garlic scallions from early March until May,  depending on how long our supply lasts out, and when we need the space for something else. Harvesting is simple, although depending on your soil, you may need to loosen the plants with a fork rather than just pulling. Trim the roots, rinse, bundle, set in a small bucket with a little water, and you’re done! Some people cut the greens at 10″ (25 cm) tall, and bunch them, allowing cuts to be made every two or three weeks. We tried this, but prefer to simply pull the whole plant once it reaches about 7-8″ (18-20 cm) tall. The leaves keep in better condition if still attached to the clove. Scallions can be sold in small bunches of 3-6 depending on size. If you do have more than you can sell in the spring, you could chop and dry them, or make pesto, for sale later in the year.

Misato Rose winter radish
Photo credit Southern Exposure Seed Exchange

This week we also harvested our winter storage radishes, which we sowed in July. Winter radish varieties have large roots that may be round or long, with white, red, pink, green or black skin. They can be eaten raw, pickled, mixed in stir-fries or cooked like turnips. Our favorites are:

  • Shunkyo Semi-long  (32 days, OP), 4-5″ (10-12 cm), smooth, cylindrical, attractive rose-pink roots with crisp white flesh. The flavor is hot and sweetly nutty. The pink-stemmed leaves can also be eaten. This slow bolting variety can be sown throughout the year in mild climates.

The other varieties in this list are all day-length sensitive, for summer to fall sowing only. They bolt if sown in spring.

  • China Rose (55 days, OP). AKA Rose Colored Chinese, Scarlet China Winter. About 5″ (12 cm) in diameter. Round, with white flesh, pink skin. Cosmetically, this variety is more variable and less beautiful than Shunkyo.
  • Red Meat (50 days, OP). AKA Watermelon. Large round roots, 2-4″ (5-10 cm), depending on how long you let them grow. Green and white skin, with sweet dark pink flesh. Large leaves.
  • Misato Rose (60 days, OP). AKA Chinese Red Heart. Green and white skin, rose and white “starburst” flesh. Beautiful when sliced for salads. Unlike many radishes, this one will still bulb properly if crowded, according to Southern Exposure Seed Exchange. Attractive, spicy, not sharp, with “a rich sweet vegetable undertone.” Can grow as large as a big beet if given sufficient space. A good keeper.
  • Shinden Risoh Daikon (65 days F-1 hybrid). Daikon (pronounced “dye-kon”) is the Japanese word for radish. Daikon are huge long white roots which store very well and stay crisp for months under refrigeration. They can be grated or sliced thin for salads, pickled, or sliced and chopped for stir-fries. Kim Chee is a traditional Korean pickle made with daikon and napa Chinese cabbage. Daikon can also be harvested small.
  • Miyashige Daikon (50 days, OP). 16-18″ (40-45 cm) long by 2.5-3″ (6-8 cm) in diameter. These “stump-rooted” cylindrical white radishes are pale green near the crown. Very crisp and tender for pickling and storage.

China Rose winter radish
Photo credit Southern Exposure Seed Exchange

This year we grew 45′ each of Shunkyo Semi-Long, China Rose, Red Meat and Shindin Risoh Daikon. In terms of yield, the China Rose is the clear winner: 54 lbs from 45′.

And they look very smooth and attractive. Next best in yield was the other pink one, Shunkyo Semi-Long at 25 lbs. The daikon came in at 21 lbs, lower than I expected. Maybe we should have thinned more drastically. A big disappointment was the Red Meat at only 15 lbs. Mind you, this one sells itself on its impressive looks. See the picture above.

Miyashige White Daikon,
Picture credit Southern Exposure Seed Exchange