How to Care for Lilacs

Lilac branches

The Fragrant and Beautiful Lilac …

May’s long weekend is usually right around the corner, when lilacs start blooming in Southern Alberta. This also signals the best time for you to start preparing your patio plants, shrubs and garden. Here are a few useful pointers to help you decide whether lilacs are for you if you have considered including them in your garden but are not sure about their soil, planting and pruning requirements.  

Lilac Growing Basics

Even though you can find some varieties that grow best in warmer climate, most lilac species require hardiness zone 3-7 climates; look here to identify your zone. You can find a full page on lilacs that grow well in warmer climates on the USDA Hardiness Zone Map.

  • Well-drained alkaline soils are great for growing lilacs.
  • Even though some shade can’t hurt them, lilacs perform better when grown in direct sunlight.
  • Powdery mildew is a common issue for lilacs; you can reduce the likelihood of occurrence by providing sufficient space for the circulation of air when planting them.
  • It may take up to 3 years for new shoots to start forming flower buds.
  • To encourage the formation of new buds the following year, remove spent blossoms with a pair of sharp clippers or deadhead them.

Deadheading lilacs is essential for the first three or four years, after maturity it becomes less important. To form new flower buds, a mature plant, in addition to being too high, the plant won’t need deadheading to encourage the formation of new buds. However, without using a ladder, I always remove as many old blossoms as I can get to.

Lilac branch on a table

Lilac Pruning Requirements

As a rule of thumb, you should only start pruning, and shaping, your lilac plant when the main stem’s diameter is 2” and the height is anywhere between six and eight feet.

After the spring flowering season is over, it is time to start pruning the plant. Newly formed buds will have all summer to develop when you prune early. You might end up pruning away the buds for next spring if you do it too late. 

Prune away around one third of the plant’s stems to keep it looking fresh. Branches that grow across each other, diseased and dead stems, twiggy growth and pencil thin sucker should be removed.

To allow the growth of new shoots and the circulation of air around the shrub, remove large stems from the center of the plant. 

Even though the choice to allow the plants to grow tall or to a manageable height is all up to you, when left to their own devices, the plants can grow to a height of more than 15 feet.

lilac shrub

Some Interesting Facts About Lilacs

You can eat lilacs! A simple, tasty and attractive lilac flower garnish prepared by a “Canadian Foodie”.

Categorized under the Oleaceae (olive) family, the lilac is a lowering plant whose botanical name is Syringa vulgaris.

The term syrinx or syringa roughly translates to “hollow tube” in Greek. Ages ago, flutes and reeds pipes were fashioned from the shoots of lilac plants.

The term Vulgaris on the other hand roughly translates to well-known or common. Just to show how common lilacs are, there are more than twenty known species of the plant, with over 2000 documented cultivars.

Brought to North America back in the seventeenth century, the popular S vulgaris lilac originated from the rocky hills of the Balkan Peninsula.

Canadians, myself included, are encouraged each year to start planting when we see and smell the sweet flowering lilac blooms. I guess the main reason is that the May long weekend is considered as our time to prepare our gardens; and these flowers typically bloom in May.