Growing Garlic In Saskatchewan

Garlic (Allium sativum), a member of the Amaryllidaceae (Amaryllis Family), is a herbaceous perennial that is often grown as an annual crop.  Garlic has been grown for more than 5000 years and is thought to have originated in central Asia around the Caspian Sea and eastward toward China.  Eventually, garlic was distributed to China, the Middle East, and Europe, and ultimately to other continents. Garlic was probably first grown in Saskatchewan by Russian and East European immigrants who brought their own garlic strains with them.

The Plant

Garlic is a bulbous plant that goes dormant in winter. The bulbs are composed of smaller divisions called cloves, which may vary in number from 3 to 40, depending on the variety and growing conditions. The long, narrow, flat leaves are borne alternately on the stem and are green or bluish-green. Some strains of garlic will flower (called hardnecks) while others (softnecks) rarely do. Those that flower will produce small bulbils rather than seeds. 

Hardneck garlic is generally considered more flavorful and is easier to peel, with fewer, but larger cloves. Softnecks tend to store much longer than hardnecks and can last for up to a year. Recent research in Saskatchewan has indicated that garlic grown in northern climates represents better planting material than garlic grown at more southerly locals. 

Garlic will break dormancy after about 4 months in storage.  It is a hardy plant, adapted to cool growing seasons.  Many cultivars will survive very low temperatures in winter, and even young tops are quite frost tolerant.  Roots will grow at temperatures above 8ºC.  Temperatures above 30ºC, however, tend to inhibit bulb formation and cause foliage to senesce prematurely. For this reason, it is important for garlic to get an early start after snowmelt, so that vigorous top growth will occur in May and June, allowing for bulb formation in July.

Cultivation- Propagation

True garlic seed is not available without specialized techniques used under controlled lab conditions. This means that almost all garlic bulbs today are propagated vegetatively and are essentially clones of each other.

Bulbs are either purchased or selected from a grower's own harvest and then separated into cloves just before planting. This procedure is known as cracking and can be very labour-intensive when done by hand. The use of a screwdriver or cracking tool can help with the process.

Buyers should purchase the healthiest stock available. Only healthy cloves should be planted and it is preferable to plant the largest cloves available. Growers generally retain a part of their crop for replanting the following season. It takes approximately 6000 bulbs (depending on the variety) to plant 1 acre of garlic and yield about 50,000 bulbs at harvest. 

Hardneck garlic produces bulbils, which can be planted just like cloves. These, however, only produce single cloved bulbs (called rounds) in the first year. This means that most large gardeners or commercial growers do not generally use them as planting stock.

Varieties

There are hundreds of varieties of garlic available worldwide, but only a small number have been researched in Saskatchewan. Yields have not always been consistent within a given variety. It is recommended that growers do their own variety trials prior to undertaking commercial-scale plantings. The main family groups that have consistently overwintered and yielded well in Saskatchewan include: Purple Stripe (e.g. Persian Star), Porcelain (e.g. Music), Rocambole (e.g. Spanish Roja) and Artichoke (e.g. Italian Softneck).

Local growers may be able to provide or recommend other cultivars as well. Elephant Garlic is not a true garlic, but rather a large garlic-like leek, and is far less hardy than regular garlic.  

Time of Planting

Garlic can be planted in spring or fall, however, fall planting is generally recommended. Although there is an increased risk of crop failure due to winter kill when planting in fall, yields are significantly higher than spring planting. Fall plantings are usually covered with at least 4 to 6 inches of mulch to protect the garlic over winter and help mitigate issues with winter kill.  

Fall planting should occur from mid-September until the middle of October in Saskatchewan. Planting on the earlier side will usually give the plant roots more time to establish before winter. The cold winter will break the dormancy of the cloves and allow growth to begin in early spring.

If garlic is to be spring planted, the garlic bulbs should be chilled in the refrigerator for at least a few weeks to cause vernalization and break dormancy prior to planting. The cloves should be planted as soon as possible in spring. This early planting will allow the plant to obtain sufficient size by late June when bulbing begins.  Late planted crops will bulb poorly and give very poor yields.

Field Site and Soil Requirements

A field, which has not recently been planted to onions, should be chosen. Garlic is a poor competitor, meaning that fields with weed problems should be avoided. The planting site should be in full sun, and well-drained. Garlic can be grown successfully on most soils, including sand and clay. Sandy loams to clay loam soils are preferable. The heavier the soil, the more difficult cleaning of bulbs will be at harvest (especially under wet conditions).

Organic matter content is desirable for holding moisture, nutrients, and to reduce soil crusting.  Rotted manure or green manure crops can be used to improve soil organic matter content prior to planting.  Soil pH of 6.0 to 7.5 is acceptable.  If the soil is light, good irrigation is necessary and wind protection is desirable. 

Fertility requirements are similar to onions.  If soil nitrate-nitrogen content to 60 cm is above 90 kg/ha (80 lb/acre), no additional nitrogen is required.  On very infertile soil, up to 130 to 180 kg/ha (116-130 lb/acre) of N can be added.  The applications should be split into three to five applications, with the last application provided 4 to 6 weeks before harvest. Phosphate levels should be around 175 kg/ha (156 lb/acre) and potash levels between 225 and 450 kg/ha (201 and 401 lb/acre).  The latter is incorporated into the soil the fall prior to planting.

Planting in Field

Cloves are planted 1-3 inches deep (soil above the cloves), with in-row spacing of about 4-6 inches. Rows should be a minimum of 10 to 12 inches apart. Spacing is usually determined by weeding methods or cultivation equipment preferred by the grower. Cloves are generally hand planted in small plots, but for commercial-scale production, a planter is desirable to reduce labour costs.   

Irrigation

Garlic requires adequate moisture during growing and bulbing and is very sensitive to moisture stress. Most soils require at least 1 inch of water per week. On sandy soils, at least 2 inches of water per week is required. Ideally, watering should occur during the morning and cease by mid-afternoon, to allow the foliage to be dry overnight. It is desirable to keep garlic dry in the fall prior to harvest, as this helps with harvesting, cleaning, and reduces staining of bulb wrappers. Generally, watering should be reduced or eliminated 2 to 3 weeks prior to harvest to help reduce soil moisture. 

Weed Control

Garlic is a very poor weed competitor and therefore weeds must be diligently controlled. It is preferable that the field is summer-fallowed the year prior to planting. Most growers, (especially organic) find garlic very labour intensive. Mechanical or hand weeding should occur often and when the weeds are small.

Conventional growers have only a few herbicide options that are registered in Canada for garlic. Poast Ultra will control grassy weeds while Pardner and Dacthal will control certain broadleaf weeds.  Devrinol DF is registered for both broadleaf and grassy weeds in garlic.

Scape Removal

Hardneck garlic will produce a long flowering stem (scape), which ultimately produces bulbils. The scape should be removed early during its development, as this practice increases bulb yields, particularly in northern climates. There is some suggestion that too early removal of the scapes may cause the bulbs to store poorly. 

Insect and Disease Control

Garlic is prone to the same insects as onions. Onion maggots, thrips and wireworms are potential pests, but they have not been serious in commercial plantings in Saskatchewan.

Viruses are often found in garlic planting stock but are generally latent and cause little problems. When grown under stress, virus-infected garlic may lack vigour and produce low yields, particularly if multiple viruses are present. Tissue culturing can be successful in eradicating viruses, however, virus-free planting stock is not generally available.

Fungal diseases such as white rot, basal rot, botrytis and Penicillium mould may be found in garlic planting stock or in the field. Fungicides have not proven effective and so the main method of control is to purchase high-quality planting stock and to eradicate diseased plants as they are found.  Excessive soil moisture in the fall will promote fungal diseases, as will wounding the garlic during cultivation and harvesting. Garlic needs to be stored under optimum conditions to minimize fungal problems. 

Harvesting

Harvesting of garlic in Saskatchewan generally occurs at the beginning of August, however, every location can have varying dates. Digging should beginning when about 1/3 of the leaves have died back and at least 4 or 5 leaves are still green. This allows sufficient time for the bulbs to mature while preventing harvesting from occurring too late. If left in the ground too long, bulbs may stain, split open and become prone to fungal infection. Harvesting is usually accomplished by hand pulling or by using an undercutter.

Following digging, the bulbs must be cured. This can be done in the field for the first week and/or indoors (very good ventilation is required). A temperature of approximately 20ºC for 20 days is desirable. Following curing, the tops and roots are removed and the bulbs brushed to remove loose skin, dirt and roots.

Storage

The ideal storage temperature for garlic is 0ºC.  At higher temperatures, bulb weight loss, rots and sprouting become a problem. Relative humidity should be in the range of 60 to 70% to minimize disease problems, sprouting and root growth.  There should be good air movement within the storage room. Garlic will store 5 to 8 months under these conditions, depending on the variety stored. Garlic can also be stored under dry, room temperature conditions, as many homeowners do, however, they will dry out and deteriorate much quicker.

Planting stock should not be stored at very cold temperatures just prior to planting but should be held at 6 to 10ºC for a few weeks. 

Yield

Yield of garlic varies according to growing conditions, cultivars, planting time and plant spacing in the field. In general, a good crop should yield about 5 to 6 times what was planted. About 15 to 20% of the harvested crop is usually kept for future plantings.

Yields on the prairies of 2-4 tonnes/ha are common and up to 10 tonnes/ha is possible. Production practices and weather conditions play a major role in affecting yields. Bulk garlic is usually sold by weight and graded according to size. Retail garlic sold to customers is often sold by the bulb and also graded according to size. 

Marketing

Most garlic produced in Saskatchewan is sold directly to consumers through farm gate sales, farmers' markets or smaller grocery stores. As well, many garlic growers find that value-added production is desirable. Pickled products, braided garlic and garlic powders are among the most popular.

Organically produced garlic is generally in high demand at farmers’ markets.  Imported bulk garlic has kept commercial prices depressed since the 1990's and has made large-scale sales of bulk garlic difficult. Potential growers should carefully investigate markets before starting large-scale production of garlic.

References

  • Bodnar, J, B. Schumacher and J. Uyenaka.1997.
  • Garlic Production. Ontario Ministry of Agriculture, Food and Rural Affairs.
  • Engeland, Ron L. 1991. Growing Great Garlic.  Filaree Productions, Okanogan, WA
  • Saskatchewan Herb & Spice Association. 2000. The Grower’s Guide to Herbs and Spices.

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