It’s lilac season in the cooler climes of North America. Your Road Trips Gardener has already highlighted three of the top lilac festivals: Lombard, Illinois (May), Rochester, New York (May) and Mackinac Island, Michigan (June).

The International Lilac Society Convention takes place May 13 through 16, 2010, at the Shelburne Museum in Shelburne, Vermont

Other lilac festivals on the flowering calendar are:

Hulda Klager Lilac Festival, now through May 9, 2010, Hulda Klager Gardens, 115 South Pekin Road, Woodland, Washington.

Lilac Sunday, May 9, 2010, Arnold Arboretum of Harvard Arboretum, Boston, Massachusetts.

Lilac Festival, May 28-31, 2010, McLaughlin Gardens, 97 Main Street, South Paris, Maine.

Fourth Street Lilac Festival, May 30, 2010, Calgary, Alberta, Canada

And, Road Trips Gardeners who are lilac fans definitely should plan to get to the Royal Botanical Gardens, 680 Plains Road West, Burlington,Ontario, Canada, to see the Katie Osborne Lilac (Syringa) Collection (Lilac Dell and Lilac Walk) in May or early June. The Gardens are home to the largest lilac collection in the world. RBG is also the home of the International Registration Authority for new lilac cultivars, and a site for their display and evaluation. From the 26 wild lilac species native to eastern Asia and southern Europe, breeders have developed over 1,600 cultivated varieties.

Another great place to see lilacs is the Lola & Milton Flack Lilac Collection (see photo by Emily Levine, at right) in the Earl G. Maxwell Arboretum at the University of Nebraska in Lincoln. This is a new collection, begun in 1981, and the entire collection is listed online.