Garlic Almanac and Phenotypic Plasticity

Silverwhite Silverskin garlic
Photo Southern Exposure Seed Exchange

Garlic Almanac and Phenotypic Plasticity

(How garlic adapts to its locality)

It’s garlic harvest season for many of us and I notice many growers are searching my site for information. Here are quick links.

Garlic signs of maturity from October 2020

Everything You Need to Know About Garlic includes all the links listed below here.

Much about garlic is to be found in my Alliums for the Month Series:

Garlic harvest.
Photo Twin Oaks Community
Other posts about garlic, starting with harvest:
Pulling garlic scapes.
Photo Wren Vile

Phenotypic Plasticity

Phenotypic plasticity of garlic refers to the changes to a garlic variety grown in a particular location. Genetically identical garlics can grow differently in different environments. Garlic reproduces asexually, the new cloves are all clones of the mother plant, with no new genetic material introduced. And yet, over time, garlic saved and regrown each year in a certain locality will adapt itself to that location, due to the particular soil type, water availability, local temperatures, latitude, altitude and cultural practices. For example, studies have shown that varieties grown in drought-prone areas can, over years, develop more drought-tolerance. Commercial cultivars can have the highest bulb yield under well-watered conditions, but drought will show up the adapted strains in a comparison trial.

Garlic Plants
Photo credit Kathryn Simmons

We have been growing our own strain of hardneck garlic for over 30 years, and it does really well here. Originally the seed stock was a bag of garlic from the wholesale vegetable market. This is the very thing we are told not to do, as it may introduce pests and diseases. Indeed, it may, but our original folly is now deep in the past, and we have fortunately seen no problem.

I was reminded about phenotypic plasticity, when a friend and neighboring grower reported that the seed garlic we had passed on to her was doing well and was mature a couple of weeks before the variety she normally grows.

From the 2004 work of Gayle Volk et al, Garlic Seed Foundation analyzing 211 garlic accessions, we have learned that there are many fewer genetically distinct varieties of garlic than there are named varieties. Of the 211 accessions in that trial, only 43 had unique genotypes. But garlic shows high biodiversity and ability to adapt to its environment. The same garlic genotypes in different environmental conditions can show different phenotypes. This demonstrates the high phenotypic plasticity of garlic, probably linked to its complicated genetics, which somehow compensate for lack of sexual reproduction.

Work done in 2009 by Gayle Volk and David Stern, Phenotypic Characteristics of Ten Garlic Cultivars Grown at Different North American Locations  addressed the observation that garlic varieties grown under diverse conditions have highly plastic environmental responses, particularly in skin color and yield. This is a very readable paper for non-academic readers. Ten garlic varieties were grown at twelve locations in the United States and Canada for two consecutive years to identify phenotypic traits of garlic that respond to environmental conditions. The purpose of the study was to determine which phenotypic traits are stable and which vary with location.

Inchelium Red softneck garlic – note the small cloves in the center.
Photo Southern Exposure Seed Exchange
  • Clove number, weight and arrangement, clove skin coloration, clove skin tightness and topset number, size and color stay true to variety independent of location.
  •  Mostly, varieties classified as hardneck types produced scapes and those classified as softnecks did not, but there were some exceptions.
  • Bulb size, bulb wrapper color and bulb elemental composition (flavor) are related to location, (the influence of the local environment, such as the weather in that production year and the soil mineral content), rather than variety. The intensity of the skin patterns is highly dependent on the location. Some general trends were noted, but no clear correlation was found. (Read the study for the details).
  • For good size, predictably colored and flavored garlic, buy seed garlic grown locally that yields well. When garlic is grown in similar conditions to those in which it was produced, yields can remain consistent or improve.

    Our softneck garlic in May.
    Photo Pam Dawling
  • Varieties that grow well thousands of miles away are not a guarantee of a good result in your garlic patch. They may not match the bulb size, shape, color and flavor listed in the catalogs.
  • When grown under the same environmental conditions, the leaf number before bolting, flowering date, the final stem length, the flower/topset ratio, and pollen viability vary from one variety to another.
  • Studies that compared bulb firmness, pH, soluble solids, moisture content and sugar content with appearance determined that many of these traits are independent of skin color across 14 garlic varieties.
  • Bulb size was highly dependent on growth location with northern sites producing larger bulbs overall than southern sites for at least half of the trial varieties. Regional differences between varieties with respect to bulb size were noted, but because the project had a limited number of sites, specific variety recommendations for different regions were not provided.
  • Bulb size and weight were positively correlated with soil potassium levels.
  • Bulb sulfur and manganese content (flavor) were correlated with soil sulfur and manganese levels.

    The famous Music garlic, a hardneck type – see the stem.
    Photo Southern Exposure Seed Exchange
  • The demand for high-quality fresh garlic is increasing as restaurants and consumers seek out local vegetables. Consumers are attracted to colorful, unique garlic varieties for different culinary uses. As variety name recognition in garlic increases, understanding which traits define particular varieties and which traits vary within cultivars, depending on environmental conditions, will be valuable for successful marketing of new garlic types.

Hoophouse Squash Variety Trial, Garlic Recap, Flowers for Organic IPM

Golden Glory Squash in our hoophouse in mid-June.
Photo Pam Dawling

Hoophouse Squash Variety Trial

A month ago I wrote about our hoophouse squash variety trials for pollination issues and blossom end rot. I think our problem was mostly unpollinated squash, rather than blossom end rot. Go to last month’s post for valuable links to distinguish the two conditions.

We planted 15 Golden Glory zucchini (good at setting fruit without pollinators) along with 25 Gentry yellow squash (a favorite variety, except that we had pollination troubles with it in our hoophouse for several years). The trial is almost over, we’re about to pull those plants, and we have plenty of squash coming in from our outdoor plantings now. The first outdoor planting includes some Golden Glory too, so if I have more news I write about it when it happens.

Gentry yellow squash in our hoophouse in mid-June
photo Pam Dawling

As I said last time, I recorded the number of small rotting squash we removed. The Golden Glory produced far fewer rotten unpollinated fruit.

Date 15 Golden Glory plants: rotted fruit Golden Glory: rotted fruit per plant 25 Gentry plants:

rotted fruit

Gentry:

rotted fruit per plant

5/13 2 0.13 12 0.48
5/14 2 0.13 5 0.2
5/17 0 0 32 1.28
5/21 15 1 54 2.16
5/27 9 0.6 39 1.56
6/4 13 0.9 29 1.2
6/10 2 0.13 11 0.46
6/14 2 0.13 9 0.43
Average per plant   0.38   0.97

 But low numbers of rotted fruits is not the only goal! Yield is important too, and the healthiness of the plants (which relates to yield).

We noticed that the plants were starting to die, and we thought of bacterial wilt. But when I tried the test for that disease, the results were negative. The test is to cut through the plant stem, rub the cut ends together, then slowly separate them. If the plant has bacterial wilt, there will be bacterial slime in strings between the stem ends when you slowly draw them apart. We got nothing like that. More research needed!

We pulled the dying squash, put them in a black trash bag and set that in the sun to cook.

Diseased squash, mid-June.
Photo Pam Dawling

Here’s what we found:

Date 15 Golden Glory plants: Number of healthy plants Golden Glory: Percentage of plants healthy 25 Gentry plants:

Number of healthy plants

Gentry:

Percentage of plants healthy

6/4 15 100% 25 100%
6/10 15 100% 24 96%
6/14 15 100% 21 84%
6/18 10 67% 20 80%
6/24 6 40% 18 72%

Initially, the Gentry started to keel over, then suddenly the Golden Glorys weren’t so glorious!

As far as yield, we did not measure it much. We only have notes from one day, 6/10. We harvested 7 squash from 15 Golden Glory plants (47%) and 14 Gentry from 24 plants (60%). Different people harvested on different days, meaning sometimes they were picked bigger than on other days. My sense is that the Golden Glory were not as productive throughout their harvest period. They are beautiful, the plants are open, easier to harvest from, and we had fewer rotten squash, and initially fewer dying plants. Is this enough to recommend them for an early hoophouse crop in future years?

My inclination is to also try another variety that is rated well for setting fruit without pollinators (hence fewer tiny rotting squash) and try harder to also record yield as well as problems next year!

—————————————————–

Garlic Recap

Our garlic is at the “Trim and Sort” stage, but depending where you garden, yours may be at a completely different stage. See my blogposts from the previous year, when I posted my Alliums for the Month Series.

Trimming garlic stems.
Photo by Brittany Lewis

—————————————————–

For people in colder climates than Virginia, you may be just starting to harvest your garlic. Learn from Margaret Roach (who grows in Massachusetts) in A Way to Garden

—————————————————–

Here are a couple of allium resources that didn’t make it into the Alliums for the Month Series

Mulching alliums

The Nordells on mulching alliums

RAMPS

Barry Glick sells ramps

“The Cat Is Out Of The Bag”!!!
Sunshine Farm & Gardens
696 Glicks Road
Renick WV 24966 USA

Ramps plants.
Photo Sunshine Farm and Gardens

—————————————————–

Flowers for Organic IPM

This is my post on the Mother Earth News Organic Gardening Blog

Organic Integrated Pest Management involves tackling pest problems one step at a time with ecologically-based practices, starting with reducing the chances of the pest ever getting a grip on your crops. Follow prevention with avoidance, and finish with pest-killing if needed. I recommend the ATTRA online publication Organic Integrated Pest Management. Each  page is a poster, complete with good photos and concise clear info.

In May we transplant flowers in our vegetable garden to attract pollinators and pest predators. We like a combination of sunflowers, dill, borage, cosmos, calendula, tithonia (Mexican sunflowers), zinnias. See my earlier Mother Earth News post Insectaries: Grow Flowers to Attract Beneficial Insects

We sow sunflowers about every 10ft (3 m) in each of our bean beds. We are growing sesame surrounded by French marigolds in our hoophouse to deter nematodes, which we have in parts of our hoophouse soil. Sesame is apparently particularly good in deterring root knot nematodes, the type we have.

French marigolds and sesame to deter Root Knot nematodes in our hoophouse.
Photo Pam Dawling

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.