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The scientific truth about garlic varieties

Garlic diversityBy Lynn Byczynski 

Photo by Gayle M. Volk
When getting started with garlic production, growers soon learn that there are literally hundreds of named cultivars or strains available in the U.S. and Canada. Choosing among that wealth of options is a challenge that has befuddled many beginners. As Ron Engeland wrote in his book Growing Great Garlic, “Professionals have wrestled with the problem of garlic varieties for over 100 years and basically succeeded in creating a very fine mess with very little agreement.”

Fortunately, science has come to the rescue of garlic growers and provided some definitive information about the confusing subject of garlic varieties. Now it’s known that all varieties can be sorted into 10 basic types; that there is a great deal of duplication among the so-called varieties; and that many with different names are genetically very similar. It’s also known that some of garlic’s most important traits are determined by location, soil, climate, and the skill of the grower.

For beginning garlic growers, here are the basics :
Botanically, all culinary garlics are in the species Allium sativum. There are two sub-species: the hardneck or ophio garlics, which have scapes; and the softneck garlics, which don’t.
Hardneck garlic is more flavorful and the cloves are bigger and easier to peel than softnecks. Softneck garlic, the kind usually found in supermarkets and often imported, has the best storage life and is easier to braid than hardnecks. 
Growers with freezing winter weather can grow either hardneck or softneck garlic, but have the best success with hardnecks. Growers in warm winter areas do better with softnecks.

Sorting through the names
In 2003, Dr. Gayle M. Volk of USDA’s National Center for Genetic Resources Preservation in Fort Collins, CO, did DNA fingerprinting of 211 varieties of garlic. Many were so genetically similar as to be statistically the same. However, she found that there are 10 distinct types: silverskin and artichoke are the two softneck types; rocambole, porcelain, purple stripe, marble purple stripe, Asiatic, turban, creole, and glazed purple stripe are hardneck types.
In 2005, Dr. Volk and David Stern of the Garlic Seed Foundation led a project in which 10 cultivars, one of each of the 10 types, were grown by garlic farmers in 12 locations around the United States and Canada. The cultivars were ‘Ajo Rojo’, ‘Chesnok’, ‘German White’, ‘Inchelium’, ‘Purple Glazer’, ‘Red Janice’, ‘Sakura’, ‘Siberian’, ‘Silverwhite’, and ‘Spanish Roja’.  The small-scale, sustainable farmers were provided with planting stocks from the same original sources and were asked to grow them on their farms for two consecutive years using their best practices. The harvested bulbs were analyzed for quality, wrapper color, yield, clove characteristics, and elemental composition. Here are the significant findings reported in the August 2009 issue of HortScience:

“Clove arrangement, number of topsets, topset size, topset color, number of cloves, clove weight, clove skin color, and clove skin tightness were generally stable for each cultivar regardless of production location and conditions.  Soil potassium levels were positively correlated with bulb circumference and fresh weight. Soil sulfur and manganese levels were correlated with bulb sulfur and manganese content. Bulb wrapper color and intensity were highly dependent on location and cultivar. The Silverwhite cultivar was consistently white and ‘Ajo Rojo’, ‘German White’, ‘Inchelium’, ‘Sakura’, and ‘Spanish Roja’ were generally white with some faint violet or brown stripes or splotches across the locations. In contrast, cultivars Chesnok Red, Purple Glazer, Red Janice, and Siberian were more likely to have moderate or dark violet stripes, streaks, or splotches, particularly when grown at the northern Colorado, Minnesota, Nevada, New York, Ontario, Pennsylvania, or Washington locations.”

The implication for growers is that the variety you plant may look different in size and color when you harvest it, especially if you purchased it from a distant supplier. Dr. Volk’s advice is to trial a number of different varieties representing the different types.  She suggests that, at the least, you grow an artichoke, silverskin, purple stripe, porcelain and a rocambole. Skilled growers can grow almost all types well, she said, so personal taste and market success may be the most important factors to consider when assessing a variety. Once you have determined the type that works best for your farm and markets, you can begin to propagate your own stock, selecting the biggest and best bulbs to plant the next year. In this way, you develop your own strain adapted to your conditions.
For detailed descriptions and photographs of the 10 types of garlic, visit

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