Things to consider before purchasing garlic planting stock

There is a lot of enthusiasm around growing garlic in Ontario. There are a few things that should be considered before starting this crop to ensure years or even decades of successful production.

Commercially-grown garlic is an asexually-propagated crop, meaning that each generation is a genetic clone of the previous generation. Asexually propagated crops can also pass along diseases to the next generation; pathogens that were in the mother plant are planted as daughter cloves the following season.

Here are some things to consider before purchasing new planting stock or trying garlic as a new crop;

• Start small, go through the entire process of planting, growing, harvesting and selling a crop before investing in large equipment
• Test planting stock for stem and bulb nematode before planting; the nematode lives in the clove and often is not noticed until their populations reach high levels in the third or forth year of growing; the ~$50 test could save you from crop failure three to four years from now

• Ask the planting stock seller if they have ever had white rot (Sclerotium cepivorum) on their farm; this pathogen very destructive and makes the plants unmarketable. There are no pesticides or management strategies that can control white rot other than prevention; spores can persist in the soil for at least 40 years

• Hardneck cultivars are the most common cultivar with ‘Music’ being the one that tends to be grown the most; see a list of Ontario planting stock providers here: https://www.garlicgrowersofontario.com/market-place-buy-sell
• Most growers plant in September-October; planting early could allow the plant to bolt and not overwinter, planting late limits adequate root growth before winter that is required for optimum yields
• Plant only cloves that appear in good condition; rogue out cloves with nicks, bruises, lesions or holes caused by insects
• Planting density depends on tractors/equipment/weed control methods and whether bulb size or yield is valued more; an average of 1200 lbs/acre of planting stock is required with rows being 18” apart and 6” between plants within the row
• Irrigation is key in dry years; a dry year could expect an average yield loss of 35% where an average year you could expect 10% loss
• Scapes in hard neck cultivars are best removed in early June by hand to increase bulb size
• Harvest when 40-60% of the leaves turn yellow (often 2nd-3rd week in July) and remove harvested bulbs from direct sun
• Cure by reducing humidity until the outer skins are dry and crispy, the center of the cut stem is hard, and the neck is constricted at the bulb
• Avoid planting garlic in the same area for at least 4 years to reduce the chance of pests and pathogens building in the soil

Types of Garlic Planting Stock

Types of planting stock	Definition	Pros	Cons
Conventional planting stock	General planting stock sold in the marketplace	-Most economical option available	-May have nematodes or other pathogens present; always test samples before planting and keep separate from other plantings for three years
Nematode-free planting stock	Planting stock that in theory, has been tested for stem and bulb nematode and is from fields that do not have stem and bulb nematode present	-Free of stem and bulb nematode means no surprises / crop failure 2-3 years from now	-May be marketed as nematode-free when in fact it is not; test a sample of cloves prior to planting; relies on trust with the seller
Certified Organic planting stock	Planting stock from a field that is certified organic. Certified to meet the requirements of an organic certification body	-Can charge a premium if organic certification status is maintained going forward	-May have nematodes present; always test samples before planting and keep separate from other plantings for three years
Clean Seed / Roundels / Clean Planting Stock	-Roundels (0.3-2 gram planting stock) that are from a clean-seed program that are tested and known to be free of known garlic viruses, nematodes and all other garlic pathogens	-Free of viruses and nematodes can potentially increase yields by 25-50% compared to conventional planting stock once it is has been grown for 2-3 years	-Most expensive -Limited number of roundels available yearly for purchase by members of the Garlic Growers Association of Ontario
Clean Seed / Successive generations of Clean Planting Stock	-Bulbs produced from roundels from a clean-seed program	-Increased vigour, and low levels of pathogens present depending on how each generation was grown from the roundel	-Limited amounts of 2+ generation planting stock available for purchase -Will not remain ‘clean’ if planted in fields with stem and bulb nematode or other pathogens present

Interested in more information? Attend a garlic production and pest management workshop for a detailed breakdown about growing garlic Ontario. Topics include cultivar selection, seeding spacing and density, crop insurance, weed control, pathogen and insect identification and management, crop rotation, scaping, clean seed production, upgrading equipment, cleaning, grading, curing and storage. Subscribe to the ONvegetables.com blog for a notification when the next workshop is scheduled. Currently, the next workshop is scheduled for August 19th, 2022 in Janetville, ON.