DAYtrip

Lilacs

at the U.S. National Arboretum

By Mark L. DeBard

I visited the lilac collection at the U.S. National Arboretum (USNA) in Washington, DC, last year in late April. I was welcomed and assisted by Kevin Conrad, curator for woody landscape plants; Harlan Svoboda, herbarium curator; Susan Greeley, field manager for research plots; and Margaret Pooler, research leader. USNA has 334 lilacs in their possession, including most of the 10 natural and 15 hybrid species, but most of them are in private research areas. However, scores of lilacs are in their main public viewing area, easily accessible from either the New York Avenue or R Street entrances, seven days a week from 8am to 5pm. Because this is a research collection and not a featured garden collection, there is no public map or signage available to the lilac area nor for any individual lilac. But this won’t prevent you from enjoying the wide variety of early and common lilacs in this area (primarily S. vulgaris). It’s wonderful to enjoy the expected great lilac fragrance while viewing many of the unusual, unnamed test lilacs in the area. There is a free U.S. National Arboretum mobile app that can help you navigate the vast grounds of the Arboretum via a digital map. A search feature allows you to enter Latin or common names and locate specific plants on the grounds. Lilacs come in seven widely recognized colors: white, violet, blue, lilac, pink, magenta, and purple. Common lilacs can be bred to have double flowers as well. There are four types (or Series) of lilacs that don’t interbreed and bloom one right after the other, prolonging the blooming season for 8–10 weeks. An individual lilac will bloom 10–20 days, depending on the weather. Watch for the important feature of contrasting bud color, since the lilac bloom slowly moves from the base to the tip of the panicle. If you’re lucky, you’ll notice some of the few named cultivars present, such as the multipetal blue ‘Wedgwood Blue’ or the deeply contrasting dark- and light-pink double ‘Sweetheart’ (pictured on page 15), or the soft-pink gradations of ‘Maiden’s Blush’. If you wander through the public research collection, look for one lilac whose florets have a “whirlybird” appearance—a trait that has become common and favored in the newer Eastern European cultivars, but is rare in North America. It will have a nicely saturated purple color. Perhaps you can find the deep-purple one that has a branch with a rare sport mutation of white buds and purple corolla giving rise to two-tone flowers. Or perhaps you’ll notice the violet one that has highly reflexed floret tips that point backward (most lilac petals are flat or cupped inward). I love the one with fabulous saturated magenta color and densely packed giant florets. Another great hybrid that has a nice contrast of dark-magenta buds with lighter-pink florets, but the

florets have lots of color gradations and are long, thin, and spaced apart so they can be clearly seen, with some white edging. Very interesting. There is always competition to see which lilac has the deepest purple color. USNA has a candidate: Look for the darkest purple you can see with nice cupping of the florets, a contrasting lighter backside, and giant florets and panicles. And did I mention the fragrance? Intoxicating to walk through the collection. As a bonus, the azalea and rhododendron collections will be blooming about the same time. Go see them both. o

Mark L. DeBard, MD, is a retired emergency physician whose retirement hobby is indulging his lilac passion. He is a Master Gardener, an officer and member of the Board of Directors of the International Lilac Society, and registrar for the International Register & Checklist of Cultivar Names for the Genus Syringa. DeBard lives in Columbus, OH, where he grows 170 different lilac cultivars in-ground and 50 more in pots.

2022 is the Year of the Lilac!

The National Garden Bureau has declared 2022 the Year of the Lilac. Here are some facts about this enchanting shrub. See even more at https://ngb.org/year-of-the-lilac/. • Lilacs have myriad uses in the garden. In addition, new sizes, a wider range of growing zones, and reblooming characteristics make them attractive and accessible to gardeners who may not have thought about growing them in the past. • Clusters of small, four-lobed flowers are borne in conical to narrow pyramidal clusters (panicles) up to 8 inches long that stand out from the green heart-shaped leaves. • Carl Linnaeus first described the lilac genus, Syringa, in 1753. The name is derived from the ancient Greek word syrinx, meaning pipe or tube. The stems of the common lilac have a spongy pith that can be removed, leaving hollow tubes that were used to make panpipes. • Rejuvenate an overgrown plant or one that blooms sparsely by cutting onethird of the oldest branches back to 12 to 15 inches from the ground. Do this over a three-year period to refresh the plant without sacrificing blooms. • These plants are at home in so many types of themed gardens, including pollinator, butterfly, cutting, fragrance, cottage, deer-resistant, and single-color (white, purple) gardens. Some are used for firescaping and firewise gardens. o