Growing Garlic in British Columbia

In British Columbia, garlic is mostly planted in the fall and harvested the next summer. The following provides information on growing garlic in British Columbia, including, varieties, planting techniques, types of seed, soils, fertility, weeding, harvesting, storage and pest control.

Garlic (Allium sativum) is in the Alliaceae family, along with its cousins the onion, shallot and leek. The majority of the garlic grown in British Columbia is either produced for home use or sold fresh to customers as whole bulbs, green garlic, scapes or garlic powder.
 

Varieties

There are two types of garlic grown in British Columbia - hardneck and softneck. Hardneck varieties will bolt during early summer, producing a tall, flower stalk called a scape. Bulbils, which are small aerial cloves, are produced at the tip of scapes in place of a true flower.

There is a huge variation in the size and number of bulbils produced by hardneck garlic. They range from hundreds of small rice sized bulbils inside a single capsule, to a handful of large pea sized ones. Bulbils may be used as planting stock, but usually, require at least 2 years to develop into marketable bulbs. Often bulbils will form a single cloved bulb called a round, which can be replanted again to form a larger, multi-cloved bulb the next year.

Softneck varieties do not generally produce a scape, however, in cold climates like the colder parts of British Columbia, some bulbs will sometimes form bulbils in the stem. A general rule of thumb is that hardneck varieties are more winter hardy, produce larger cloves but have a shorter storage life than softneck varieties.

Traditionally, hardnecks were the main choice for growers in British Columbia, however, there are now hardy softneck varieties that are suitable for most regions of Canada (especially when covered by straw mulch). Softnecks can do especially well in the coastal areas of British Columbia where the winters are mild and spring comes early.  

Hardneck garlic can produce anywhere from 4-12 cloves per bulb. The main family groups grown in British Columbia include Rocambole, Porcelain, Purple Stripe and Marble Purple Striped. Softneck garlic varieties produce an average of 8-12 cloves/bulb. The main softneck family group grown in British Columbia is Artichoke.

Regardless of type, cultivated garlic plants do not produce true seed, therefore, no crossing or exchange of genetic material occurs between strains of garlic. All garlic is propagated vegetatively from cloves or bulbils, with each clove or bulbil being a clone of the parent plant. Over many hundreds and even thousands of years, rare mutations have occurred, resulting in the different varieties we see today.

For more specific information see The Best Garlic Varieties For British Columbia 

Purple Stripe (left) and Rocambole (right) garlic varieties.

Planting

Garlic is a perennial plant that requires a cold period for proper bulb growth to occur. In British Columbia, garlic is generally planted in the fall and harvested the following summer. Although fall planting is recommended, it is still possible to plant in the spring (see Growing Garlic in Spring for more info).

For colder regions of British Columbia, planting is usually done sometime between the end of September until the end of October. For the milder coastal areas such as Vancouver and Victoria, planting is usually done between the middle of October and the middle of November.

It is important that garlic is planted at the right time before winter.  Planting too early or too shallow risks having the shoots emerge above the soil surface and being exposed to extremely cold winter temperatures. This can cause die back of the leaves that have emerged or even death of the plant if the conditions are severe enough. If planted too late, there is a risk that cloves will not develop a large enough root system in order to establish themselves before winter arrives.

If planting is done at the right time, a strong, well-established overwintering plant will explode out of the ground in spring as soil and air temperatures warm up. If moisture and fertility are adequate, large healthy plants will develop before bulbing takes place. These large plants will then have the ability to produce maximum sized bulbs because of the large leaf surface area which is able to contribute more energy to the bulbing process. 

When possible, it is also important that cloves are planted with the pointed side up. Cloves planted on their sides can still grow nice bulbs, however, they sometimes develop curved stocks and misshapen bulbs. Many commercial growers plant cloves on their sides using seeding equipment, however, most gardeners and market growers, plant by hand with the tips pointed up.

Seed

Seed garlic should be kept as whole bulbs right up until just before planting. Cloves tend to start dehydrating and deteriorate quickly once they have been "cracked" and the bulbs are no longer intact. Dry bulbs are usually easier to crack and brake into cloves than damp bulbs. The cracking process can be done using mechanical devices or by hand. Mechanical cracking is much faster and is much less work, however, it has a greater potential to physically damage the cloves during the process.

The number of seed bulbs required for planting ranges from 5000 to 9000 bulbs per acre (approximately 50,000 to 60,000 cloves)  or 100 to 200 bulbs per 1000 square feet, depending on the variety planted and spacing used. Cloves should be spaced 4 to 6 in inches (10 to 15 cm) apart within the row.

Wider spacing between rows will usually allow for larger bulbs to be produced and easier weeding during the growing season. Row spacing can range from 8 to 16 inches (20 to 40 cm) depending on the planting, weeding and harvesting methods. Most growers use a spacing of between 10 and 12 inches (25 and 30 cm).

Some British Columbia growers use bulbils as a seed source. Depending on the variety, capsules can contain anywhere from four to a few hundred bulbils. One advantage of planting bulbils is that it allows growers to increase their planting stock quickly and helps reduce some soil-borne diseases from the planting stock. The disadvantage is that it can take several years of successive plantings to achieve good-sized bulbs from the initial bulbil planting. This delay is why most growers only use cloves for planting.

Bulbils tend to dehydrate very easily because of their small size and loose wrappers.This means that bulbil capsules should only be broken open and individual bulbils removed just prior to planting. Bulbils can be planted closer together then cloves, however, they can be hard to weed if planted to closely. An in-row spacing of between 1 and 4 inches (3 and 10 cm) is a good range for most growers. 

Irrigation is very important for bulbil seedlings due to their shallow root systems. They should be watered regularly and throughout the growing season. 

Capsule containing large Rocambole bulbils.

Soils and Fertility

Garlic grows well on a wide range of soil types including both sand and clay. It can be cultivated anywhere in British Columbia that can grow cool season vegetables.

Soils with high organic matter content are preferred, due to their increased moisture and nutrient holding capacity. Soils containing high levels of organic matter tend to be less prone to crusting and compaction. Heavy clay soils can be challenging during wet periods (although conditions can be improved greatly with the use of raised beds). Consistent irrigation and water conservation practices are required on light sandy soils due to their low moisture holding capacity.

 

Garlic is a heavy feeder and grows very well on fertile soils. Poor fertility is one of the most common reasons growers end up with small bulbs. To help ensure optimal nutrient levels, it is best to apply a balanced Organic Fertilizer when possible. Fertilization can be split into three or four applications. Once in the fall and two or three times in spring. 

If using conventional fertilizer, all the phosphorus and potassium should be added and incorporated before planting. About 1/3 of the nitrogen should be added just before or just after planting in the fall. The remaining nitrogen should be split into several applications starting first thing in spring and ending about one month before harvest. 

Taking a soil test before planting garlic is recommended in order to verify nutrient levels. The following are general fertility recommendations for garlic in Manitoba, however, they could be higher or lower depending on the soil type, length of growing season and previous crop grown.

Nutrient	Pounds per Acre	Pounds per 1000 ft2
Nitrogen	120 lbs (55 kg)	3 lbs (1.3 kg)
Phosphorus	160 lbs (73 kg)	4 lbs (1.8 kg)
Potassium	150 lbs (68 kg)	4 lbs (1.8 kg)
Sulphur	30 lbs (14 kg)	1 lb (0.5 kg)

Fertility recommendations for growing garlic. 

 

 Planting Location 

For colder locations in British Columbia, it is best to plant garlic in a sheltered location where good snow cover occurs. This will protect the cloves over winter and help prevent winter kill. Adequate shelter also reduces wind speeds which prevents wind erosion, especially on light sandy soils.

It is important to pick a location with good drainage, especially on heavier soils. There should be proper access to water if irrigation will be required. Large trees close to the planting area should be avoided, as well as any areas that are infested with perennial weeds
.

Mulching

In much of British Columbia and the rest of Canada, many growers mulch for the winter. Mulching helps moderate soil temperatures and protects the cloves from any harsh winter conditions that arrive. This can be especially important in British Columbia where drastic warm weather can occur during the winter resulting in all the protective snow cover melting before spring. The most commonly used mulch is straw, applied 4 to 6 inches deep directly over the planted garlic rows.

In the spring, some growers remove the mulch completely once the threat of frost is over, while others leave it on throughout the season to help maintain moisture and provide weed control. On heavy soils, leaving the mulch on can cause excess moisture issues, sometimes leading to disease.

Garlic rows covered with straw mulch for the winter.

Irrigation

Garlic is sensitive to moisture stress throughout the growing season. Periods of dry soil conditions, especially during bulb formation, will result in reduced yields.

On clay and loam soils, approximately 1 inch (2.5 cm) of water per week is required during the growing season. On sandy soils, 2 inches (5.0 cm) or more of water can be required during hot, dry weather.

Preferably, garlic should be irrigated in the morning to mid-afternoon. This allows sufficient time for the plants to dry before evening. Irrigation should be stopped around two weeks before harvesting. This will make the harvesting process easier and help reduce potential deterioration or staining of the bulbs.

Scape Removal

Hardneck garlic varieties produce a scape that should be removed if maximum bulb size is desired. Research shows that bulb size can be reduced by as much as 30% when scapes are not removed. This is because energy is diverted to growing bulbils instead of increasing bulb size. Remove scapes by snapping or cutting them just after the have one or two curls (depending on the variety), but before they straighten out. In British Columbia, this is usually some time between early June and the beginning of July.

A Purple Stripe garlic scape ready for removal.

Harvest

Garlic bulbs continue to grow in size during late spring and summer until the leaves of the plant begin to die. This process starts with the lower leaves as they dry and turn brown from the tips towards their base. Harvesting should begin when 30%-50% of the leaves have died and turned brown. This usually means about 3 to 5 leaves having died and 3 to 5 still green, depending on the variety. Bulbs that are harvested too early will be immature and will likely shrivel when cured. Late harvested bulbs tend to be stained and often have deteriorated wrappers with exposed cloves.

For small growing areas of garlic, hand harvesting can be done by using a pitch or broad fork to loosen the soil and make removal easier. Large plantings of garlic are usually harvested mechanically with an under-cutter blade pulled by a tractor that cuts the roots and loosens the soil, making harvesting by hand less work. For very large farms, there is mechanized equipment that can be used to lift the bulbs and remove the tops all automatically in one operation.

Curing

Curing is the process of drying bulbs in order to increase storage life. This is done by reducing moisture content which results in the reduction of microbial and fungal growth.

Garlic should be cured immediately after harvest and can be left in the field to begin drying for a couple of days. Plants should be laid on the ground in single layer rows. When laying down the garlic plants, use the tops to cover the bulbs of the previous row to protect them from sun scalding.

Alternatively, the garlic can be removed from the field immediately after harvest and brought inside for the entire curing process. Plants can be tied in bundles of 10 and hung to dry or the tops can be removed and the bulbs placed into slotted crates, on wire racks or on open trays in a well ventilated area.   

Similar to bulbs, bulbils must be cured prior to storage. Harvest scapes with the bulbil capsule intact just prior to garlic bulb harvest. Once harvested, bunch, tie and hang scapes to dry for a few weeks. Once dried, remove the bulbil capsules and store them in a dry location until the time of planting.

 
Harvested garlic laying in the field to dry for several days.

Storage

Storage conditions for garlic depend on the end use. Garlic for consumption (table stock) can be stored differently than garlic for planting stock. Garlic for table stock is best stored at 0°C-4°C with a relative humidity of 60%-70%. Avoid storing in higher humidity, as this creates an excellent environment for penicillium mould and root growth. Table stock can also be stored at room temperature in a cool well-ventilated area but may dehydrate faster. Store garlic intended for planting stock at anywhere from 10°C to room temperature with 60%-70% relative humidity. Plant as soon as possible to prevent deterioration of the bulbs.

At room temperature, hardneck varieties can usually be stored up to 5 months and softneck varieties up to 10 months. In temperature and humidity controlled conditions, storage life can be increased to 8 months for hardnecks and over 12 months for softneck types.

Weed Management

Garlic plants are very weak competitors and require dedicated weed control in order to maximize bulbs sizes. Weeding can be done with hand hoes, wheel hoes, tillers, mechanical cultivation with a tractor, mulching or with herbicides. Garlic plants have very shallow roots that can be damaged easily, meaning that care should always be taken when tilling or cultivating. Damage to the garlic roots can reduce yields significantly.

Garlic field that has been weeded several times throughout the growing season.

Insects and Diseases

There are a number of pests and diseases that can affect garlic. Some occur frequently, while others are rarely seen in British Columbia. The most common pests include, bulb and stem nematode, Fusarium basal plate rot, Penicillium mould, and viruses.

Fusarium Basal Plate Rot

Fusarium basal plate rot attacks the basal plate region of the bulb and roots. This soil-borne pathogen invades the roots, resulting in empty, tan-coloured, non-functional roots, while the basal plate region may develop a pinkish-brown growth of mycelium. Above-ground symptoms include yellowing of the leaf tips and dieback of the shoot during the spring. Warm soil temperatures and high soil moisture promote disease development. Since the organism survives as dormant spores in the soil or on plant residue, rotate with non-allium crops. 

Penicillium Mould

Penicillium mould is the main cause of decay of garlic in storage. The disease appears as masses of blue-green growth usually first seen at the base of the bulb. The primary source of inoculum is diseased bulbs used for planting material. When diseased bulbs are cracked, healthy cloves may be contaminated with airborne spores. Wounded cloves are particularly susceptible to this disease.

Infected cloves are often invaded by secondary decay organisms such as bacteria and other fungi, masking the original pathogen. Clove rot and reduced plant stands are often the result of planting infected cloves. Warm temperatures (22°C-25°C) are optimal for spore germination and disease development. Planting garlic too early in late summer when soil temperatures are high may increase the severity of clove rot. Irrigation may be beneficial, as high soil moisture appears to suppress clove decay.

Bulb and Stem Nematode

Bulb and stem nematode is a microscopic parasitic nematode that enters garlic through the roots or wounds on bulbs. Early in the season, young seedlings infected with nematodes are often stunted, with yellowing and bloating of young leaves. Later infections can cause twisting of new growth, bulb softening and desiccation, and loss of roots.

Bulb and stem nematode becomes active in the spring with damage symptoms generally appearing mid-July through harvest. The key to management of this pest is prevention. This means planting nematode-free seed into nematode-free soil. Test your soil before planting, use clean seed and follow a 4-year rotation with non-host crops. Once in the soil, bulb and stem nematode can be spread through irrigation water, on contaminated seed, equipment, humans and animals.

White Rot

White rot is a soil-borne fungal disease that can survive as sclerotia in infected fields for decades. It is a serious concern, particularly in cool, wet growing seasons. Symptoms of white rot of garlic include yellowing, wilting and toppling over of older leaves, watery bulbs and the presence of a fluffy, white mycelium and pinhead-sized black sclerotia, as well as rotted roots. Because sclerotia and mycelium overwinter in the soil and plant debris, thorough cleaning of field equipment and properly disposing of cull garlic is necessary for preventing the spread of white rot to uncontaminated fields.

Viruses

Virtually all sources of garlic contain viruses, though most are latent (dormant). Latent garlic viruses may not become visible or reduce yields until the garlic plant is stressed or growth is interrupted. The most common symptoms of virus infection are colour changes of the leaves. These include mosaics, flecking, streaking and mottling. Leaf shape distortion may also occur. Always remove plants that look diseased or sick from the field during the growing season.

About the Author: John Côté owns and operates John Boy Farms with his family who have been farming the same land for over 140 years. As an agronomist and experienced farmer, he helps others learn how to grow garlic successfully. He has written many articles and is the author of The Master Guide to Growing Big Garlic.