Select lilacs fastidiously, or find yourself with high-maintenance shrub

The sight and perfume of lilacs, blooming in shades from deep violet-purple to pink to white, are among the many splendors of spring.

If you happen to’d wish to have that splendor in your yard, watch out concerning the lilac you select, mentioned Julie Janoski, Plant Clinic supervisor at The Morton Arboretum in Lisle. “They’re wonderful for about two weeks in Could, however the remainder of the time, old school lilacs is usually a lot to deal with,” she mentioned.

Essentially the most acquainted species is widespread lilac (Syringa vulgaris), a plant from the Balkans that’s well-liked around the globe and has been planted in Chicago-area gardens because the nineteenth century. Many decades-old lilacs survive immediately.

Mature shrubs are sometimes 15 to twenty ft excessive and simply as vast. “They’re vigorous, spreading shrubs that want a number of area,” Janoski mentioned.

If a lilac must be pruned, do it quickly after the shrub finishes blooming. “If you happen to wait too lengthy, you’ll scale back the spring bloom subsequent yr,” she mentioned.

That’s as a result of lilacs develop subsequent yr’s flower buds over the course of every summer time. “You’ve a window of three or 4 weeks to prune,” Janoski mentioned. “After that, you’ll be slicing off subsequent spring’s flowers.”

Lilacs attempt to kind clumps by sending up new shoots from spreading roots. “Prune out the suckers to maintain the lilac beneath management,” she mentioned.

An previous lilac usually turns into a dense tangle of thick, gnarly previous stems, useless wooden and new shoots. This crowding can impede circulation and encourage powdery mildew, a standard downside with older types of lilac. Opening up the inside of the shrub by pruning can enhance air move and restore vigor.

There are two methods to tame a tangled previous lilac: renewal pruning and rejuvenation pruning.

For a gradual method that retains lilac blooms coming each spring, attempt renewal pruning. First take away all of the useless wooden, slicing useless stems as little as you possibly can. Then take away the thickest, oldest residing stems, pruning them off inside 1 or 2 inches of the bottom. “Take out solely one-third of the residing stems,” Janoski mentioned. The remaining stems will help the shrub with their sun-gathering leaves and can bear spring blooms.

In every of the subsequent two years, take away one-third of the oldest stems, and hold eradicating useless wooden. By the fourth yr, all of the stems might be youthful and extra vigorous. “After that, examine annually and prune as essential to hold the large tangle from returning,” she mentioned. “At all times take away the oldest stems, and be sure to by no means take out greater than a 3rd of the plant.”

For a extra drastic, much less painstaking method, attempt rejuvenating the shrub. Reduce off all of the stems — the entire plant — inside 1 or 2 inches of the bottom. Subsequent yr, new stems will sprout, however they received’t have blooms. “You’ll lose a yr of flowers,” Janoski mentioned. The primary blooms will seem the next spring, and it’ll take a number of years for the shrub to get again to its full dimension.

Not all lilac issues might be solved by pruning. For instance, it received’t restore bloom to a shrub that’s in an excessive amount of shade.

Lilacs in nature solely develop in full solar in well-drained soil, in response to Kris Bachtell, vice chairman of collections and amenities on the Arboretum. With out full solar, they received’t bloom.

In gardens, previous lilac shrubs that had been planted in full solar might now be in shade as a result of bushes have grown overhead or newer buildings now block the solar’s rays. “There’s nothing you are able to do to make a lilac bloom if it doesn’t have sufficient solar,” Janoski mentioned. “It’s simply a big nonflowering inexperienced shrub.”

For gardeners who don’t have the area or endurance for an old school lilac, a number of extra manageable species and cultivated varieties can be found. These smaller lilacs often don’t require as a lot pruning as old school lilacs, needing solely occasional pruning for form.

Meyer lilac (Syringa meyeri) grows 6 to eight ft excessive and vast. Though it blooms greatest in full solar, it could tolerate half shade. It blooms barely later than the widespread lilac. The most typical cultivar is Palibin.

Manchurian lilac (Syringa patula) is thought primarily for one cultivar, Miss Kim. It has aromatic mild purple flowers that fade to mild pink on a plant that’s 5 to eight ft tall.

Reblooming lilacs are hybrids that bloom once more in late summer time or early fall, though not as lushly as in spring. The Bloomerang collection contains a number of cultivars, together with Bloomerang Purple (Syringa ‘Penda’); Bloomerang Darkish Purple (Syringa x ‘SMSJBP7′); and Bloomerang Dwarf Pink (Syringa x ‘SMNJRPI’). They’re all smaller than the widespread lilac, however sizes differ amongst cultivars, so analysis every plant and select the best dimension on your yard.

For tree and plant recommendation, contact the Plant Clinic at The Morton Arboretum (630-719-2424, mortonarb.org/plant-clinic, or plantclinic@mortonarb.org). Beth Botts is a workers author on the Arboretum.