Plant information and physiology
Garlic's scientific name is Allium sativum, a member of the Alliaceae family and closely related to onions, chives, shallots, and leeks. It is a perennial bulbous plant, even though the majority of producers grow it as an annual. Garlic has long, flat, green leaves, slightly V-shape, arising directly from the bulb or a short pseudostem. Leaves height varies from 30-60 cm (12-24 inches) and 5-7 cm (2-3 in) wide depending on the variety, while the stem can reach 5-6.5 cm. The shallow adventitious root system of the plants develops right under the bulb. The bulb consists of many smaller individual bulbs known as cloves. The number and the size of cloves depend on the variety and the growing conditions.
Broadly speaking, most varieties contain 5-30 cloves (around 10-12 per bulb). Garlic plants can produce a few hermaphrodite flowers with spherical clusters inside 2 paper resembled bracts. The blossom's color varies from greenish-white to red and has 6 or more petals. The blooming period for garlic is summer (July-August) in most areas.
Garlic thrives in hardiness zones 4-9. Garlic gives the best quality products in temperate climates with full sun exposure. Most garlic varieties need cool winters (1-2 months at 0-10 oC or 32-50 oF), followed by mild spring temperatures to initiate bulb formation. However, too low temperatures may lead to the formation of fewer and smaller bulbs. The ideal temperature for garlic growth is 13 to 24 oC (55-75 oF). The daylight also affects bulb formation (photoperiod=duration of day and night), but to a lesser extent than onions. As a result, depending on the region, farmers must select a suitable garlic variety adapted to local conditions (short-day or long-day types).
Types and varieties of garlic
While over 600 cultivars of garlic are available in the market, scientific data reveal that all are closely related to just 10 varieties. All these cultivars are classified into 2 major categories-types: Hardneck and Softneck (or common garlic). These 2 garlic types can be further subcategorized into other groups based on the photoperiod needs, the color, number, and size of bulbs and cloves they produce, the flavor, and the self-life expectancy.
- The Hardneck (Ophioscorodon) includes the Rocambole (most commonly grown), Purple Stripe, and Porcelain types.
- The Soft-neck (Sativum) includes Artichoke and Silverskin.
The Hardneck garlic can be found in white, purple, or purple-striped color, producing long scapes with fewer but larger cloves per bulb. The plants produce around 4-12 cloves with a relatively short shelf-life. This type of garlic is mainly cultivated in cooler climates due to its particular temperature preferences.
Some of the most commonly cultivated varieties are: German Red, Chesnok Red, Glenlarge, Italian Pink, Persian Star, New Zealand Purple, Metechi, Valencia, Spanish Roja, Creole, Roja, Music, Georgian Crystal, Brown Tempest, and Continental.
The Softneck garlic varieties are more adaptive to warmer climates and are largely cultivated in the Mediterranean, South Europe, and California. Plants of this type do not produce flower stalks and tend to give higher yields than the Hardneck varieties (smaller but more cloves (around 12-20, or even 40) per bulb). We mainly find it in white color and has a more intense, spicy flavor than the sweet Hardneck varieties. Moreover, these garlics have a longer shelf-life compared to the ones of the other category. The most commonly cultivated varieties are: California Early, California Late, Idaho Silver, Italian White (1 and 2), Susanville, and Printan.
References
- https://www.nda.agric.za/docs/brochures/prodguidegarlic.pdf
- https://extension.uga.edu/publications/detail.html?number=C854#Garlic%20Cultivars
- https://www.agric.wa.gov.au/garlic/growing-garlic-western-australia?nopaging=1
- https://hort.extension.wisc.edu/articles/garlic-allium-sativum/
- https://www.hvgf.org/garlic-varieties
- https://dogr.icar.gov.in/index.php?option=com_content&view=article&id=126&Itemid=178&lang=en
- https://www.rhs.org.uk/vegetables/garlic/grow-your-own
- http://cceonondaga.org/resources/garlic-varieties
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