Did you know that there are over 2000 named lilac cultivars (cultivated varieties) of lilacs throughout the earth? Read more about lilacs at the International Lilac Registrar website. This website provides a bit of background on cultivar name registration, has a link to the downloadable Register files (lists of named lilac cultivars), and has contact information to the Registrar.

Lilac Color and Classifications

Lilacs are categorized by color and by whether the bloom is single or "double." (In fact, there are several kinds of double lilac blooms and even some triples that are classed as doubles.) The bloom is listed as "S" for Single, or "D" for double.

Lilac blooms are graded for color when 1/3 of the buds burst open. Color evaluation should take place in the shade before the bloom has a chance to fade. Of course, your own lilacs may exhibit differences in color from the official color grade. Differences in color can result from such things as soil pH, local climate or recent weather, and how much sunlight your plant receives.

Roman numerals are used for listing lilac colors. The following colors are the names used for lilacs:
    I - White
    II - Violet
    III - Blue
    IV - Lilac
    V - Pink
    VI - Magenta
    VII - Purple
(Some European organizations also recognize VIII - Creamy Yellow.) So, for instance, a lilac that is "S V" is a single pink lilac.

View the 4-year Lilac Study at Lilacia Park, The Morton Arboretum, etc. (published in 1978) to learn more about your own lilac collections.