What can you tell me about lavender cultivars and propagation?
Answer: Lavender?a small, non-hardy, perennial, evergreen shrub?is best propagated from softwood cuttings of standard types. Seed may not come true to type, and lavandin seeds are sterile.
Different cultivars are raised for different purposes. Most growers favor deep blue flowers, lush growth, and hardiness. Other types of lavender?such as ?Spike’?are not commonly grown in the United States, except as specimen plants. White and pink forms of L. angustifolia are curiosities sometimes seen in home gardens. Although some California growers favor ?Irene Doyle’ for its fragrance, ability to flower bi-annually in Zone 7, and its slightly darker lavender blue flowers, the most commonly grown cultivars in all parts of this country are the lavandins ?Provence’ and ?Grosso’. ?Grosso’ attracts attention in tourist areas, creating a striking effect of large fields of “purple haze.” It is very hardy and grows to three feet in height. Products of acceptable quality can be made by judiciously blending ?Grosso’ distillate with imported sweet oils.
The English lavender (L. angustifolia) cultivar ?Munstead’ is commonly grown in New England, as is the lavandin (L. x intermedia) cultivar ?Grosso.’ ?Munstead’ is reportedly the only English lavender that does well at high altitudes and was recently reported doing well in Nevada. Nurseries may market cultivars of L. angustifolia and L. x intermedia (lavandin) under deceptively similar names. For example, ?Hidcote’ is L. angustifolia, while ?Giant Hidcote’ is L. x intermedia.
The different cultivars of lavender vary slightly in specific gravity (s.g.) and have distinct chemical profiles. Because lavender oils are lighter than water (s.g. of less than 1.0), they rise to the top. The lower the s.g., the more easily the oil is volatized. More information on distillation parameters can be found in E. Guenther’s The Essential Oils, four volumes (1948-52); Brian Lawrence’s The Essential Oils, three volumes (1976-78); the Journal of Essential Oils; and the Journal of Agricultural Food Chemistry. Chemical profile affects the olfactory properties of an essential oil and, hence, the quality.
You’ll benefit from reading ATTRA’s recently updated its publication Lavender Production, Marketing, and Agritourism. This publication discusses geographic and climatic considerations for lavender, soil-preparation and cultivation techniques, lavender propagation, and field production. It also addresses marketing options for lavender, including essential oils, essential-oil distillation, direct marketing of a variety of lavender products, and information and resources about lavender agritourism and value-added lavender products.