Soil Requirements, Soil Preparation, and Planting of Garlic

Soil Requirements and Preparation for garlic cultivation

For garlic cultivation, soil can rarely be a restrictive factor since it can survive in a wide range of soil conditions. However, the plant thrives best in middle composition to sandy soils with good drainage, a pH 6 to 7, and rich in organic matter (about 5% is ideal). Avoid clay, compacted, and reddish soils since they will negatively affect sprouting and bulb formation and may color the skins, reducing the product’s quality. In general, the plants have good drought tolerance. On the other hand, it does not like soggy soils. In heavy, compacted soils, tillage may be needed before planting to improve drainage. As an alternative, growers may rotate garlic with other crops that need tillage. However, in most cases, there will be a need to loosen up the soil before planting the garlic cloves. Plowing (15-20 cm or 6-8 inches deep) removes rocks and other undesirable materials from the soil, and it is an efficient weed management measure for perennial weeds. Finally, in compacted soils with poor drainage, farmers choose to plant garlic in raised beds.

One week after plowing the field, many farmers apply a pre-planting fertilizer such as well-rotted manure, plant-based products (like alfalfa meal), or synthetic (mineral) commercial fertilizer, always after performing a soil analysis test and consulting a local licensed agronomist. It is essential to provide sufficient amounts of nitrogen (in slow-release forms), phosphorus, and potassium to the plants at the first stages of their lives.

Most farmers integrate top dressing on the same day, using tillage tractors. The next day is the right time to install the drip irrigation pipes. Following the installation, some farmers can apply soil disinfection substances through the irrigation system if soil analysis has revealed soil infection problems (ask a licensed agronomist in your area).

The next step is optional. It is mainly used in countries with non-optimum soil temperatures during planting and is the linear polyethylene coating. Some producers cover the rows with black or green Infrared – Transmitting (IRT) or black plastic film. They use this technique to maintain the root zone temperature at optimum levels and prevent weeds from growing.

Garlic Planting and Planting spacing

In many garlic-producing countries, the most suitable time to plant garlic outdoors is during autumn (mid or second half) or the first half of spring. At that time, temperatures are close to 10°C (50°F). In autumn, it is essential to give the plants enough time (3-6 weeks) to develop the root system before any frost events for the plants to survive. Farmers can apply a 5-10 cm (2-4 inches) layer of straw mulch right after planting in areas prone to frost to protect the young plants and preserve soil moisture. On the other hand, if garlic is to be planted in spring and there are not enough chilling hours, it is best to store the cloves beforehand in a refrigerator for 8 weeks.

Farmers generally prefer big to middle-sized, healthy cloves for planting. It is essential to purchase the propagation material from a legitimate seller to ensure the cloves’ variety, purity, health, and good sprouting rate. At the same time, the growers should check their country’s legislation (quarantine requirements) if he/she wants to buy propagation material from abroad (in some countries, like Australia, it is not allowed for garlic for sanitary reasons). If the propagation material needs to be stored for some time before planting, it is advised to keep it as whole bulbs and place it in a protected area with good aeration and a temperature of 10 °C (50 °F). Storing at a temperature above 18 °C (64 °F) or below 5 °C (41 °F) may harm the viability of garlic cloves.

After all the preparation steps before planting (plowing, basic fertilization, installation of the irrigation system, and plastic film covering), we can proceed with planting. Growers label the exact points on the ground where they will plant the young plants. They then dig holes of 2,5-5 cm (1-2 inches) depending on the clove size and plant the cloves. Elephant garlic should be planted a bit deeper due to the larger size of the cloves (at 5-6cm or 2-2.5 inches). Planting of garlic can be performed by hand (in smaller fields or gardens) or mechanically with different types of planters (halls, trickle or cup seeders). It is important to plant only healthy cloves, with no green shoots growing and in the proper orientation (the thinner edge of the clove facing upwards). Ideally, garlic cloves should be larger than 5 grams (0.01 lb), but generally, all above 2 grams (0.005) are acceptable and can be used for planting.

As a general recommendation, for having around 320,000 cloves per hectare (or 12.800 cloves per acre) (with 50g or 0.11 lb bulb size), the farmer needs to plant:

2 tons of cloves per hectare for garlic varieties that produce 8 cloves per bulb (or 1784 lb/acre)
1.3 tons of cloves per hectare for garlic varieties that produce 12 cloves per bulb (or 1160 lb/acre)
0.5-1 tons of cloves per hectare for garlic varieties that produce 20 cloves per bulb (892 lb/acre).

A typical pattern for planting is: 8-15 cm (3.15-6 inches) distance between plants on the row and a 25-40 cm (10-16 inches) distance between rows. However, this is not always the case. Garlic can also be planted in double rows (with a 6 in. or 15 cm distance). The distances and the number of plants that will be chosen, depend on the garlic variety, environmental and soil conditions/characteristics, and of course, the yield goals of the farmer. Keep in mind that by increasing the plant density, you can obtain higher yields (up to a level) but smaller bulbs.

References

Further reading:

Garlic Plant information and Variety selection

General information and nutritional value of Garlic

Growing garlic in your backyard

Growing Garlic Commercially – Complete Growing Guide for Garlic from Start to Finish

Soil Requirements, Soil Preparation, and Planting of Garlic

Garlic Water Requirements and Irrigation Systems

Garlic Fertilization Requirements

Garlic Pests and Diseases

Garlic Weed Management

Garlic Harvest Yield and Storage

Garlic Wholesale Market

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