Garlic

Allium sativum (ophioscorodon variety—hardneck) (Alliaceae or onion family)

Production

---

Soil preparation

• There are many options to prepare the land for a successful garlic crop. Here are 2 options:
• Leave the land in bare fallow the summer before planting, usually after 2 years of red clover. Bare fallow will remove both red clover and emerging weeds. Plow under the clover in June or July. 
• To establish good weed-control tilth, you can also plant garlic after a regiment of cover crops. For example, plant a mix of oats and peas (at a rate of 100 lbs. per acre of each) as soon as the ground can be worked. Mow this cover crop and work it in when the oats have developed a flower stalk but not any pollen (anthesis), to avoid it becoming a weed. Follow this cover crop with a crop of buckwheat (at a rate of 80 lbs. per the acre). Again, work this under before the buckwheat is in full bloom to avoid it becoming a weed. 
• Apply compost and amendments based on the results of a soil test before planting or right before incorporating buckwheat.
• Spread lime as needed to increase both the pH and Ca levels. Dolomite lime will also increase Mg levels. Spread gypsum when calcium levels are low but pH is correct.
• Prepare the seedbed 1–4 weeks in advance, and shallowly stale seedbed before planting to eradicate weeds, if possible. Don’t disturb the soil too deeply, as this will bring up new weed seeds.
• Alternatively, prepare the beds no later than the end of August. (In the Northeast, this corresponds to 4–6 weeks before planting.) If the ground is dry, irrigate until the soil moisture is up to field capacity, and then place a silage tarp over the prepared beds. This will flush many annual weed seeds and reduce subsequent weed pressure. Remove the tarp when the weeds have died. 
• Some growers plant garlic through black or white plastic mulch with much success. See this article for more information.

Common recommended fertilizer rates¹

Nitrogen	Phosphorus	Potassium	pH
40-120	0-150	0-150	6.0-6.4
1Rates are for New York and are from Cornell University’s Nutrient Guidelines for Commercial Vegetable Production (2019). Check the Cornell website for updated guidelines, or consult with local experts for recommended rates outside New York.

Varieties

• Hardneck garlic varieties (Allium sativum var. ophioscorodon)
  • Hardneck garlic varieties are generally hardier than softneck varieties. They produce garlic scapes in early summer by sending up a strong central stalk in spring. Hardneck types tend to form fewer and larger cloves per bulb than softneck varieties. Within the hardneck family, there are 9 sub‐types of garlic: Purple Stripe, Marbled Purple Stripe, Asiatic, Glazed Purple Stripe, Creole, Middle Eastern, Turban, Rocambole and Porcelain. Within the hardneck type, the Porcelain (Music and German White), Marble Purple Stripe (Bogatyr), Purple Stripe (Chesnok Red) and Rocambole (German Red and Killarney Red) types are the best choice for growers in the northeastern United States and Canada.
• Softneck garlic varieties (Allium sativum var. sativum)
  • Softneck garlic varieties are the best ones to grow if you live in a milder climate. They don’t form scapes, and they generally form several small cloves per head. Softneck varieties mature quicker than hardneck varieties. Sub‐types within the softneck family include Silverskin and Artichoke.

Transplanting in 5- or 6- foot raised beds

Rows	In-row spacing	Planting depth (inches)	Notes
3-4	7 inches	Plant garlic right side up as deep as the length of the garlic cloves.	Mulch with clean straw or hay at a rate of 3 lbs. of material per foot (a 40 lbs. square bale covers about 12.5 feet). Apply before the first deep freeze.

Planting procedures

• Crack hardneck garlic by hand to avoid bruising the cloves. Machine cracking can cause greater incidence of disease, especially fusarium basal rot. Sort cloves carefully for mites, garlic bloat nematodes and fusarium.
• Plant garlic as deep as the clove is tall, with the growing point facing up. Plant in an 8x8 grid for very high populations on a smaller scale, or for larger-scale growers, plant in rows 12–15 inches apart with 7 inches between cloves within the row.
• Planting hardneck garlic with a machine isn’t advisable as the machine isn’t able to get this right. Planting rightside-up is less important with softneck garlic. 

Cultivation procedures

• Mulch directly after planting with straw or hay that is free of weed seeds. Depending on the maturity of the hay, it might break down faster than straw, so apply generously.
• Mulch will provide all the necessary weed control, making it unnecessary to cultivate.
• You’ll need to hand weed on a regular basis the season after planting.

Other cultural practices 

• You can apply additional nitrogen in early spring, but generally this isn’t advised unless excessive rain over the winter washed out the N reserves. At a yield of 4,000–5,000 lbs. garlic only takes up approximately 40 lbs. of N. High N applications are associated with lower quality bulbs and greater incidence of disease. Mulching prevents some nutrient losses over the winter.
• You don’t need to remove mulch to prevent yield loss due to cooler soil temperatures because moisture retention from the mulch may compensate for this.
• To increase bulb yield, remove (or harvest) garlic scapes as soon as they’re visible. This happens in June in the Northeast. It may happen as early as May on the West Coast. 

Insect and disease protection

• Check the soil for wireworms, as a high population will decrease yield because they feed on the garlic’s root system. To avoid wireworm damage, include buckwheat as a cover crop before planting. Some results have been obtained using beneficial entomopathogenic nematodes. Also, applications of Beauveria bassiana have had promising results. 
• Check for allium leaf miners. In southern regions, use exclusion netting to avoid an infestation. In northern regions, the moth generally emerges too late in the spring to do damage.
• Check garlic for possible infestations of white rot, dry rot and Fusarium basal rot. When a plant looks different, pull it out to inspect it, and remove all diseased plants from the field.

Double cropping and/or cover cropping

• Garlic is out of the ground by mid-July and can be followed by a number of transplanted vegetable crops that require relatively low fertility, like lettuce and escarole. 
• Work under any harvest remains and straw. The mulch will absorb much of the available N during the breakdown process so it is essential to provide some additional fertilizer to successfully grow another vegetable crop.
• Alternatively, continue to cultivate the ground and follow with a cover crop later in the season.

Additional resources

• Here is a good research report on the effects of growing techniques on yield, grade and fusarium infestation levels in garlic.

Harvest

---

Yield	An average of 0.2 lbs. dried and cured garlic per row foot from hardneck varieties
Standards	Harvesting1 35 lbs. garlic per person, per hour. This includes lifting the garlic with a bedlifter, removing the tops and putting them into boxes.
	Washing 40–50 lbs. per person, per hour
Tools and supplies needed	Gloves, a utility cutter, serrated knives, regular 1 ⅓-bushel boxes or any other plastic box (like 1 ¾-bushel), and a tractor with a bedlifter, or a fork or shovel for manual harvesting
1Harvest rates don't include the time required to transport crops from the field to a wash and pack shed or storage facility.

Ready-to-harvest and quality indicators

• The best indicator for harvest readiness is how the cloves are filling the wrapper leaves. To determine this, take a couple of average-looking plants from each variety and cut them in half perpendicular to the stem, so that you are cutting through all the cloves. For the garlic to be ready to harvest, each clove should be tight in its wrapper leaves. If there is any give when you squeeze the bulb, or if the wrapper leaves seem a little loose around the cloves, the garlic is still growing, and harvest is premature. At maturity a few of the outer wrapper leaves will probably be breaking down, which is normal.
• You can also look at the shape of each clove. Cloves start out being more or less round and expand to more of a wedge shape. On hardneck varieties, the cloves will pull very slightly away from the scape as the garlic reaches full maturity.
• If you let the garlic stay in the ground too long, too many wrapper leaves will decay, and the cloves will continue to expand until the garlic splits open. At this point the garlic becomes unmarketable.
• Make sure that you check your garlic every few days as it’s approaching maturity.

Harvest procedures

• When the garlic is ready, mow garlic at about 6 inches to avoid bringing a lot of wet material into the curing area. Pull garlic out of the ground with the help of a bedlifter, shovel or hand fork.
• Harvest in the morning to avoid sunscald, as it’s best to field dry the garlic for a few hours before taking it into the curing area. Bring it in before temperatures hit the upper 80°s.
• Either use a sharp serrated knife to cut the roots off ½ inch below the bottom of the bulb, or shake the dirt off. Never bang the bulbs to remove dirt from the roots. Any bruises will cause decay in storage. Don’t twist the roots off as damage to the basal plate of the garlic will introduce Fusarium basal rot.
• To prevent bruising, handle all garlic like apples by gently placing them in a crate for transport.

Washing procedures

• You can wash garlic straight after harvest, but only do this when field conditions are very muddy. Never wash garlic that is already drying, as this might cause the garlic to spoil.

Curing procedures

• After harvest, it’s best to cure garlic in a high tunnel on mesh benches with lots of good air circulation. Make sure the mesh is strong enough to prevent sagging in the middle. Galvanized metal wire mesh that’s 1x2 inches works well. Alternatively, use a plenum and forced air to save space.
• The high tunnel should be covered with 60% shade cloth to protect garlic from sunscald and to moderate temperature. Lay the garlic flat on greenhouse benches to allow for good aeration. Set the exhaust fan temperature to around 80°, and always keep the circulation fans on to avoid moisture buildup on the plastic.

• Curing is complete when the leaves flake off and the necks are sufficiently dried (with no evidence of moisture). This can take 2–3 weeks under optimum conditions. Do not over dry garlic, which leads to yield loss and poor storage life.

Cleaning and sorting procedures

• After curing, cut off any excess stem with pruning shears or a scissor-style utility cutter. Preferably use a utility cutter for root trimming as blades tend to get dull due to the soil particles left on the roots.
• You can remove any dirt particles by removing the outer wrapper. Do this under dry conditions so the wrappers come off easily. These conditions are favorable when the sun warms and dries the curing area (high tunnel/caterpillar tunnel).
• Check garlic for any discolorations, soft spots or other defects, and remove these bulbs from the curing area.
• After this, move the garlic to a cooler, dry area. Ideally this is a climate-controlled area like an insulated room with an AC unit keeping the temperature at around 60°. The AC unit will also maintain low moisture.
• Sort garlic for size and quality in a well-lit location when you’re ready to ship it.

Additional resources

• Growing, Harvesting, Storing and Marketing Garlic in the Northeast
• U.S. Standards for grades of Garlic
• Production Guide for Storage of Organic Fruits and Vegetables

Cleaning in the field	Cut tops, lift garlic, pull the bulbs and clean off roots.
Packing in the field	Fill in boxes for transport.
Packing for delivery	Sort to size: Small bulbs are less than 1.5 inches, medium are 1.5–2 inches and large are 2 inches and over. Pack in mesh bags or cardboard boxes at 20–40 lbs. See the International Federation for Produce Standards for the correct PLU code. Add the prefix 9 for organic crops.
Storage	SStore seed garlic at 70° and 65–75% relative humidity. For long-term storage of garlic that you plan to sell, ideally store at 32°–41° and 65–70% humidity. Garlic will sprout after being removed from cold storage. Garlic doesn’t produce ethylene and isn’t sensitive to ethylene.

This material is based upon work that is supported by the National Institute of Food and Agriculture, U.S. Department of Agriculture through the Sustainable Agriculture Research and Education (SARE) program. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and should not be construed to represent any official USDA or U.S. Government determination or policy.