Have you ever been caught behind a slow-moving car that’s obviously sightseeing? It might be me.
A favorite summer pastime is driving around town looking at trees, flowers and landscapes, and if the lineup of cars behind us gets too long, my wife, Mary, always suggests I pull over, which helps keep the horn-honking to a minimum.
Apparently, we aren’t the only ones noticing what’s growing, because an eye-catching tree currently in full bloom is prompting many questions as it’s viewed in yards and along city streets. It’s the Japanese tree lilac, whose botanical name is Syringa reticulata, with its large, billowy white flower clusters. If you didn’t know better, you might not even recognize them as lilacs, although they’re cousins of common shrub-type lilacs.
Japanese tree lilacs can be grown as single-trunked trees, or in a multi-trunked clump. They’re becoming more popular because they’re so versatile. The eventual height of a Japanese tree lilac is about 20 or 25 feet high, which classifies it as a small-scale tree, when compared to our large shade trees that can reach 60 feet.
Their neat shape makes them an ideal feature in small spaces such as courtyards, narrow side yards and close to decks and patios. The leafy canopy stays fairly low-headed, making them a great screening tree between neighboring yards, or to add privacy to backyard patios and decks. There’s a lot to like about Japanese tree lilacs.
Its prime feature, of course, is showy flowers. When the spring blooms of ornamental crabapples have faded, the Japanese tree lilac takes center stage with its display of creamy white flowers, usually blooming from about mid-June through early July, later than shrub-type lilacs.
The Japanese tree lilac even adds winter beauty. The bark is somewhat glossy and copper-colored, providing interest if planted where it can be viewed in winter. The seedheads usually persist, adding further interest. It’s one of the toughest and most trouble-free trees for landscapes.
Japanese tree lilac is winter-hardy throughout the region and is well-adapted to alkaline soil types. They grow well even in dry sites, once they become established. They can’t, however, tolerate wet, poorly drained soil, which is a common trait among all lilacs.
Like other lilacs, they require full sunshine to bloom their best. The Japanese tree lilac is a great choice for boulevards as well as yards and public landscapes. Its rounded canopy and 25-foot height fits nicely where overhead power lines are a challenge.
Japanese tree lilacs require little extra care, and they don’t have major disease and insect problems. Extra shoots or branches will occasionally sprout from the lower trunk region, and they should be pruned flush while small.
Japanese tree lilacs are readily available at garden centers, especially those locally owned. You’ll find named cultivars, including Ivory Silk, Summer Snow, Signature, and First Editions Snowdance, whose sterile flowers don’t produce seedheads.
Here’s an exciting locally developed cultivar to watch for in the near future: North Dakota State University’s Woody Plants Improvement Program has recently introduced Summer Flare Japanese tree lilac, which will hopefully be on the market soon. For locations where a somewhat higher, dramatic flowering tree is wanted, Summer Flare becomes an upright oval, taller than wide, maturing at 30 to 35 feet high instead of the usual 25, yet with a width of only 14 to 16 feet.
Don Kinzler, a lifelong gardener, is the horticulturist with North Dakota State University Extension for Cass County. Readers can reach him at email@example.com or call 701-241-5707.