Lilacs

How to Plant, Grow, and Care for Lilac Shrubs

Yankee Doodle Lilacs

Huge blooms, wonderful scent.

Wally Patrick

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Who doesn’t love lilacs? The ideal lilac shrub has about 10 canes and produces flowers at eye-level—all the better to enjoy that sweet, haunting fragrance.

Lilacs do come in seven colors, but most are familiar with the common lilac, Syringa vulgaris, which blooms in the northern states for 2 weeks in late May. However, there are early-, mid-, and late-season lilacs, which, when grown together, ensure a steady bloom for at least 6 weeks.

Lilacs are hardy, easy to grow, and low maintenance. They can grow from 5 to 15 feet tall, depending on the variety. The fragrant flowers are good for cutting and attractive to butterflies.

Planting

  • Grow lilacs in fertile, humus-rich, well-drained, neutral to alkaline soil (at a pH near 7.0). If your soil is in poor condition, add compost to enrich. Learn more about soil amendments and preparing soil for planting.
  • Select a site where your lilac will get full sun—at least 6 hours. If lilacs don’t get enough sun, they will not bloom well.
  • Make sure the site drains well. Lilacs don’t like wet feet and will not bloom with too much water.
  • Plant in either spring or fall, although the latter is preferred.
  • If you’re lucky, a friend will give you a sucker, or offshoot, of the root system of one of his plants. Your sucker will look pathetic at first but just dig a hole, backfill it with soil, and stick the sucker in. Then water and wait. In 4 or 5 years, you’ll be rewarded with huge, fragrant blossoms.
  • Transplanting lilacs from a nursery is also easy. If it’s container-grown, spread out the roots as you settle the plant into the ground; if it’s balled or burlapped, gently remove the covering and any rope before planting. Set the plant 2 or 3 inches deeper than it grew in the nursery, and work topsoil in around the roots. Water in. Then fill in the hole with more topsoil.
  • Space multiple lilac bushes 5 to 15 feet apart, depending on the variety.

Care

  • Each spring, apply a layer of compost under the plant, followed by mulch to retain moisture and control weeds.
  • Water during the summer if rainfall is less than 1 inch per week.
  • Lilacs won’t bloom if they’re overfertilized. They can handle a handful of 10-10-10 in late winter, but no more.
  • After your lilac bush has finished blooming, spread some lime and well-rotted manure around the base. Trim the bush to shape it, and remove suckers at the same time.

Pruning Lilacs

  • Lilacs bloom on old wood, so it’s critical to prune in the spring right after they bloom. If you prune later in the summer, you may be removing the wood. Here’s a tip: If your lilac flower clusters are getting smaller, time to prune!
  • Every year after bloom, remove any dead wood. Prune out the oldest canes (down to the ground). Remove the small suckers. Cut back weak branches to a strong shoot. Cut back tall canes to eye height.
  • If your lilac is old and in really bad shape, remove one-third of the oldest canes (down to the ground) in year one, half of the remaining old wood in year two, and the rest of the old wood in year three. Another option for old lilacs is to chop the whole thing back to about 6 or 8 inches high. It sounds drastic, but lilacs are very hardy. The downside to this option is that it takes a few years to grow back. The upside is less work and more reward, as the lilac will grow back bursting with blooms. 
  • It must be recognized that severe pruning results in the loss of blooms for one to three years. For these reasons, a wise pruning program aims to avoid severe and drastic cuts by giving the bushes annual attention. 

Pests/Diseases

  • Prone to attack by slugs and snails.
  • Powdery white mildew may appear after a summer of hot, humid weather. It may be unsightly, but it does no harm. Ignore it.

Recommended Varieties

Wit & Wisdom

  • To improve the flowering of lilacs, keep the grass from growing around them. A 16- to 24-inch circle of landscape cloth placed around the bushes and covered with bark or stone will keep the grass down.
  • Force a winter bouquet from cut branches of lilac. Bruise the cut ends and set them in water. Spray the branches frequently. Keep them in a cool place until they bloom, then move to a warmer area for display.
  • Poet Walt Whitman thought of lilacs when Abraham Lincoln died: 
    When lilacs last in the dooryard bloom’d … I mourn’d, and yet shall mourn with ever-returning spring.”
  • Lilacs supposedly symbolize the joy of youth. Learn about more flower symbolism here.

Reader Comments

Leave a Comment

we planted our bushes 2 years

we planted our bushes 2 years ago and had a frost i mistakenly covered them with black trash bags and they burnt since then the bushes look very healthy but have never bloomed will they ever?

lilac blooms

As you figured out, cover with cloth or fabric, not plastic. Lilacs are super duper hearty. I'm sure it will be fine. There are tips above about how to encourage blooms. When you prune/cut down a lilac, it only wants to bloom more!

Lilac Care

Some varieties of lilacs need a few years to mature. Other reasons for not blooming: A late freeze, too warm a winter (lilacs need chilling), lack of sunlight (6 hours of full sun needed), overfertilizing (not needed), soil that's too acidic (get a soil test and amend with lime if needed), and incorrect pruning (the most common mistake). Pruning helps a lilac flower. Avoid drastic pruning while your lilacs recover. See the pruning tips above.

Lilac roots

How big do the roots get? Can I plant it next to my house near my bedroom window?

lilacs near house

Plant the lilacs about 12 feet or more from the foundation to avoid worry. Lilac roots aren't invasive though they can ramble and lilacs need room to grow in all directions. The roots are about one to one-half times the length of the branches. A 10-foot shrub would have roots about 15 feet in every direction. However, the roots aren't invasive and don't worry too much about foundations.

weather requirements

We expect a frost, does anything need to be done to protecr our lilac bushes? they have started to bloom.

thanks

lilacs and frost

Most lilacs are quite cold hardy (to USDA zone 2) and the plant itself will be fine. However, if you have buds already (given this strangely warm winter), you can throw a cloth sheet over the bushes if they're not too big. The buds are damaged easily. Either you'll lose the flowers totally or the panicles will not be filled out---dead spots, a few flowers, etc.

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Botanical Name: 

Syringa

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