Getty Images: Purple lilac tree (Syringa vulgaris) at Arnold Arboretum
Many plants benefit from some form of pruning, whether it involves a light shaping or a more drastic cut to rejuvenate. One plant that particularly benefits from pruning is the lilac shrub. Over time, lilacs can become unruly and overgrown. Pruning helps maintain the plant at a manageable size, preventing overcrowding and reducing the risk of disease. One of the most appealing aspects of pruning for gardeners is that it promotes a more abundant blooming season, resulting in more flowers to enjoy in the garden or use in arrangements. Is your lilac shrub in need of a trim? Find out when and how to prune lilacs with advice from experts.
Meet the Experts:
– Linda Langelo, horticulture specialist at Colorado State University and author of “Plants Are Speaking. Are You Listening?”
– Kelly Funk, president of Jackson & Perkins, a full-service nursery offering flowers, trees, shrubs, ground covers, bulbs, and more
Benefits of Pruning Lilacs:
Pruning lilacs is crucial for their care and health. “Pruning lilacs helps maintain their health by removing old wood that can stifle the lilac,” says Linda Langelo, horticulture specialist at Colorado State University. “It also allows light to penetrate the interior of the lilac bush.” Additionally, pruning directs energy towards flower production rather than seed production, resulting in a longer and more abundant growing season.
In addition to enhancing productivity, pruning lilacs also has aesthetic advantages. “Pruning lilacs improves their shape, promotes stronger blooming, prevents overgrowth, and keeps plants healthy by eliminating dead or diseased wood,” says Kelly Funk, president of Jackson & Perkins. “Pruned lilacs tend to remain more compact and attractive in the landscape.”
When to Prune Lilacs:
Prune lilacs in late spring or early summer immediately after they have finished blooming. “This timing allows you to enjoy the current season’s flowers while avoiding accidentally removing next year’s buds, which start forming shortly after blooming,” says Funk. “Pruning too early removes current blooms, while pruning too late eliminates future ones.” Pruning in early summer gives the plant sufficient time to heal and produce new buds.
How to Prune Lilacs for Maintenance:
Maintenance pruning helps to keep your lilac bush looking neat by removing spent blossoms and damaged branches. It also aids in disease prevention by eliminating crossing branches to enhance airflow.
– Remove dead, damaged, diseased, and crossing branches to open up the center of the plant.
– Trim off spent flowers, cutting just above a healthy set of leaves to encourage tidy regrowth.
– Prune 1/3 of the oldest, thickest stems down to the ground to stimulate new shoots.
– Remove stems thicker than 2 inches in diameter to control the overall height.
How to Prune Lilacs for Rejuven
It will take a few seasons for your lilacs to bloom again using this method. Here are some tips for pruning your lilac shrub to ensure its health and vitality:
1. Maintenance pruning is best: Regular seasonal pruning helps keep your lilacs in good shape. It’s better to do annual maintenance pruning rather than rejuvenation pruning, which can be more stressful for the lilac.
2. Wait until maturity to prune: It’s not necessary to prune lilacs when they are young. Wait until the shrub reaches a height of about 6 to 8 feet before pruning.
3. Make angled cuts: Cut branches at a 45-degree angle to prevent water from collecting on the open wound, which can lead to fungal diseases like powdery mildew.
4. Use sharp tools: Always use sharp, clean tools to prevent the spread of disease and ensure clean cuts. Avoid using tools that have been used on diseased plants without cleaning them first.
5. Cut in the right spot: Trim just above a pair of healthy buds or lateral branches to encourage outward growth. Cutting in the wrong spot can hinder future growth.
6. Avoid pruning too late: Pruning lilacs too late can remove next year’s buds. Winter pruning can stress the lilac and make it more susceptible to winter damage.
By following these tips, you can keep your lilac shrub healthy and thriving.
