Caring for Lilacs

When lilacs bloom in Southern Alberta, it’s usually getting close to the May long weekend. That also means it’s time to get the garden, shrubs and patio plants going. If you’ve thought putting in lilacs but are worried about when to plant, when to prune, or even the type of dirt they prefer, here are a few ‘good to know’ basics to help you decide if lilacs will suit you!

Common LilacBasics about lilacs

  • Most species of lilacs prefer the climates of hardiness zones 3 to 7 (check your zone here) but there are cultivars that will do well in warmer zones. The USDA Hardiness Zone Map has a page dedicated to lilacs for warm climates.
  • Lilacs love well-drained soil that’s more alkaline than acidic.
  • Lilacs grow best in full sun but partial shade won’t hurt.
  • When planting, allow room for good air circulation to reduce the possibility of powdery mildew — a common problem for lilacs.
  • New shoots can take up to three years before flower buds begin forming.
  • Deadhead, or remove spent blossoms with sharp clippers, as soon as possible to encourage new buds to form for the following year.
  • As your lilac shrub matures, the job of deadheading isn’t as important as it is in the first 3 or 4 years. An established plant won’t need the extra encouragement provided by deadheading, to produce new buds — they may be too high up to clip anyway! I still remove old blooms as far up as I can reach without a ladder.

Pruning lilacs

A general rule about pruning — when your lilac shrub reaches a height of 6 to 8 feet and the main stem is 2 inches in diameter, it’s time to start pruning and shaping the shrub.

Lilac bud

Next year’s flower bud

The best time of year to prune is after the spring flowers are done. Pruning early in the season will give new buds the rest of the summer to develop; if you wait too long you risk removing next spring’s buds.

To keep the lilac shrub looking rejuvenated, remove about 1/3 of its stems. Prune dead or diseased stems, pencil thin suckers, twiggy growth and branches that grow across one another.

Trim large stems from the center of the shrub to allow air circulation and room for new shoots on the outside of the plant to develop.

If left to grow on their own, lilacs could reach heights of 15 feet or taller, but it’s personal preference whether to keep your lilacs to a manageable height or let them grow tall.

An excellent resource for pruning how-to’s is the Horticulture Gardener’s Desk Reference

Interesting facts about lilacs

  • Lilacs are edible! A Canadian Foodie makes an easy, beautiful and delicious garnish of lilac flowers.
  • The lilac, botanical name Syringa vulgaris, is a species of flowering plant and a member of the olive, Oleaceae, family.
  • Look closely at the name: Syringa or syrinx is Greek for ‘hollow tube’. In ancient times the shoots of the lilac plant were easily carved or hollowed out and made into reed pipes and flutes!
  • Vulgaris means ‘common’ or well known — there are at least 20 known species of lilacs and more than 2000 named cultivars, lilacs are indeed well known and well-loved.
  • The common lilac, S. vulgaris is native to the rocky hills of the Balkan Peninsula and was brought to North America in the 17th century.

The fragrant purple flowering lilac blooms inspire Canadians (or me anyway) to start planting. I’d say it’s because they’re in bloom during the month of May and the May long weekend is our signal that it’s finally safe to be in the garden!

Photo credit: wikimedia commons

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