Common lilac

Questions about common lilac

Does common lilac need sun or shade?

Common lilac grows in full sun (6 or more hours of direct sun a day).

It wants ordinary well-drained soil, of average fertility, and a good soak in dry spells.

What zones does common lilac grow in?

USDA zones 3 to 7. It is hardy to zone 3, which means it survives winter nights down to about −30 °F (−34 °C).

Above zone 7 it struggles: the zones measure winter cold, but a plant's top zone usually means the summers are too hot or the winters too mild for it to rest.

Gardening in Canada? Use the USDA zone for your town: Canada's own zone map uses different numbers.

When does common lilac flower in my zone?

In zone 5 it flowers early May to late May. As a spring flower it moves about a week for every zone: earlier where it is warmer, later where it is colder.

Worked out from Hopkins' bioclimatic law: spring arrives about four days later for each degree of latitude north, and one zone is roughly two degrees. A warm spring or a cold one moves any garden two weeks either way.

How far apart should common lilac be planted?

8 ft (250 cm) apart, from the middle of one plant to the middle of the next. That is a little closer than its full width of 10 ft (300 cm), so a group knits into one patch.

It grows 11½ ft (350 cm) tall. Give it the full distance from anything taller, or it will lean out towards the light.

How many common lilac plants do I need?

Usually one. At 8 ft (250 cm) across, it is a plant you place, not one you mass. For a hedge or screen, set them 8 ft apart: two plants for a 10 ft run.

In the bed above, the planner used one in one group.

Is common lilac poisonous to dogs and cats?

No toxicity is recorded for dogs, cats, horses or people, according to NC State Extension.

"Not toxic" is not "edible": a pet that eats a lot of any plant can be sick.

Is there a native plant like common lilac?

Common lilac comes from Balkan Peninsula. These North American natives come closest to doing its job:

• Carolina allspice: the same job in a bed; 3½ ft shorter, 20 in narrower.
• American cranberrybush: the same job in a bed, the same size and the same flowering time; white, not lavender, wants moist soil.

Matched the way the planner's Swap button matches plants: the same job in a bed, then size, then flowering time.

Do deer eat common lilac?

Mostly not. NC State lists it as resistant to deer and rabbits. No plant is proof against a hungry deer in a hard winter, but this one is low on the menu.

Will common lilac spread?

It spreads sideways, by runners or roots; the risk of it taking over is moderate. Spreads by suckers into a wider clump. Remove the outer shoots to contain it.

What flowers after common lilac?

Common lilac is over by late May. These start as it finishes and carry the same spot on, so it never goes flat:

• Peony: from late May to late June, 3 ft tall, to stand in front of it and cover its fading stems (a recorded partner).
• Mock orange: from late May to late June, 10 ft tall.
• Ninebark 'Diabolo': from late May to late June, 8 ft tall, to stand in front of it and cover its fading stems.

What does common lilac look like in winter?

Common lilac drops its leaves and stands as bare branches. That is when to see its shape, and to prune it if it needs pruning.

Is common lilac good for bees and butterflies?

Common lilac is visited by pollinators, bees, butterflies, moths and hummingbirds.

It is a host plant: the caterpillars of laurel sphinx and promethea moth feed on its leaves. A butterfly can only lay its eggs on its host plants, so these do more for it than any nectar flower.