How to Grow Trimming Lilac Bushes - Plant Care & Tips

By NorwichGardener Team   /   2024

Trimming lilac bushes is a great way to encourage new growth and keep your plant looking its best. It's important to wait until after the blooming season to trim, as this is when the plant is putting all its energy into flowers. Once the blooms have faded, you can trim back the stems to encourage new growth.

How to Grow Trimming Lilac Bushes - Plant Care & Tips

Also known as

  • butterfly bush
  • summer lilac
  • Japanese tree lilac
  • common lilac
  • fragrant lilac

Good to Know

  • Trim lilac bushes in early spring, before new growth begins.
  • Cut off any dead or diseased branches.
  • Cut back any branches that are crossed or rubbing against each other.
  • Thin out the bush by removing some of the older branches near the base.
  • Cut back the remaining branches by about one-third their length.
  • Make sure to use sharp pruning shears or loppers to avoid damaging the branches.
  • Try to avoid cutting into the woody part of the branch, as this will encourage new growth.
  • After trimming, apply a layer of mulch around the base of the bush.
  • Water the bush deeply to help it recover from the pruning.
  • Fertilize the bush in early spring to promote new growth.

Related plant:
Trimming Holly Bushes

Growing Steps

  1. For trimming lilac bushes, first step is to cut back the main stems by about one-third.
  2. Cut back the side branches to just above a bud.
  3. Remove any dead, diseased, or damaged wood.
  4. Thin out the interior of the bush to promote air circulation.
  5. Cut back any suckers that are growing from the base of the plant.
  6. Apply a balanced fertilizer to the soil around the bush.
  7. Water the bush deeply after trimming.
  8. Mulch around the bush to help retain moisture and control weeds.
  9. Prune again in late winter or early spring, before new growth begins.
  10. Enjoy your beautiful, healthy lilac bush!

Related plant:
Shrub Trimming

The Soil

About soil condition, the best condition for lilac bushes is well-drained soil set in full sun. They're not too particular about soil type as long as it isn't soggy. If you have heavy clay soil, raise the bed by mounding it up 6 to 8 inches and adding organic matter to help with drainage.

Light condition

So, like the other plants, lilac bushes need sunlight to grow. They should be planted in an area that gets at least six hours of sun each day. If you want your lilac bush to thrive, make sure it gets plenty of sun.

Ideal Temperature

The temperature condition is ideal for trimming lilac bushes. The sun is shining and there is a slight breeze. You will want to dress in comfortable clothing that you can move around in. A pair of gloves will protect your hands from the sharp thorns on the bushes.

Ideal Humidity

Ideal humidity condition for this plant is 50%. If the humidity drops below 40%, the leaves may begin to turn brown and drop off. If the humidity gets too high, above 60%, the leaves may develop powdery mildew.


Mentioning fertilizer, this plant loves root fertilizers. In the spring, work a balanced fertilizer into the soil around the base of the plant. You can also top-dress the area with compost in the spring.

Plant Pruning

Pruning lilac bushes is a necessary part of their upkeep. By pruning the bush, you are able to encourage new growth and keep the plant healthy. When pruning, be sure to focus on the main stems of the bush. Cut away any dead or damaged branches and then trim back the remaining branches to the desired length.

About Propagating

Propagation is the process of creating new plants from existing ones. It's a simple process that can be done with just a few tools and materials. To propagate lilac bushes, you'll need to take cuttings from the parent plant. These cuttings can be rooted in a pot of soil and then transplanted to the garden. To take cuttings, use a sharp knife or pruning shears to remove a 4-6 inch section of stem from the parent plant. Cut just below a leaf node, which is the point where the leaves attach to the stem. Strip the leaves from the bottom half of the cutting, and dip the cut end in rooting hormone. Fill a pot with a well-draining soil mix, and make a hole in the center with your finger. Gently insert the cutting into the hole, and firm the soil around it. Water the soil well, and place the pot in a warm, sunny location. Keep the soil moist, but not soggy, and in a few weeks you should see new growth. Once the new plant is established, you can transplant it to the garden.

Plant Growth

Usually, the plant growth rate is generally fast, so they will require annual or bi-annual pruning to maintain their shape and size. American lilacs (Syringa vulgaris) can grow up to 24 inches per year, while Japanese lilacs (Syringa japonica) can grow 36 inches per year.

The Problems

Common problems for this kind of plant include overgrown and misshapen shrubs. Most lilac shrubs need to be trimmed every 3 to 5 years to maintain their shape and prevent them from getting too large. Trimming also helps to encourage new growth and keep the shrub healthy.

List to Know

  • Make sure to plant your lilac bush in an area that gets plenty of sunlight.
  • Be sure to water your lilac bush regularly, especially during periods of drought.
  • Fertilize your lilac bush every spring with a slow-release fertilizer.
  • Prune your lilac bush annually to encourage new growth and maintain its shape.
  • Deadhead spent flowers regularly to keep your bush looking tidy.
  • Watch for pests and diseases and take steps to control them if necessary.
  • Mulch around your lilac bush to help retain moisture and suppress weeds.
  • Give your bush plenty of room to grow by spacing it at least 6 feet away from other plants.
  • Stake taller lilac bushes to prevent them from toppling over in strong winds.
  • Enjoy the beautiful flowers your bush produces each spring!

You May Like

  • Savel (methyl salicylate, SS-cream)
  • Savlon (antiseptic ointment)
  • Zovirax (aciclovir, antiviral ointment)
  • Elidel [(pimecrolimus) (cream)]
  • Ciclopirox (cream)
  • Miconazole (cream)
  • Ketoconazole (cream)
  • Clotrimazole (cream)
  • Triamcinolone (cream)
  • Desonide (cream)

Yard and Garden: Lilacs | News
Prune properly, your forsythia and lilac shrubs will thank you
Lilac | Horticulture, Landscape, and Environmental Systems

Richelle Author Photo
Reviewed & Published by Richelle
Submitted by our contributor
Shrubs Category