Pruning Lilacs

Pruned lilacs are more likely to bloom every year and to stay a size that suits you. They'll probably be healthier, the blooming more prolific and the flower clusters larger. Annual pruning is essential in arboretums and public gardens, where the lilacs need to look their best every spring. In the home garden, lilacs can be pruned every year or less frequently. The less frequently you prune, the bigger and more difficult the job will eventually be. In small gardens, where space is at a premium, annual pruning is essential.

Cutting lilac flowers to bring indoors is a type of pruning, not very methodical but the right idea. The shrubs quickly replaced the removed vegetation with new leaf and flower buds for next spring's show. Of course, picking flowers is too random to be a reliable pruning method. People who want cut flowers snip off only the most accessible ones. Their scissors or knives may spread disease. To do this job properly, you will need a pruning saw-preferably curved and with a strong handle-and sharp pruning shears or secateurs. For branches thicker than about an inch (2.5 cm), you may also want the leverage afforded by long-handled pruning shears. Keep your saw and pruners sharp, and disinfect them between plants in Lysol, rubbing alcohol or a fresh solution of 1 part household bleach diluted in 10 parts water.

Cut branches in one of three places: just above a bud, flush with the adjoining branch or at the ground. On all lilacs, pruning should be done as soon after the flowers have faded as you can manage. Most people aren't too fond of the look of spent lilac flowers, so this schedule takes care of deadheading and pruning at the same time. In summer, the plant forms its buds-both leaf and flower-for the next year, so don't leave pruning so late that you end up cutting off next year's flowers. Most hardy spring-flowering shrubs, incidentally, have the habit of flowering on buds developed the previous season, so you can set aside a day for pruning not only the lilacs but also white spiraea, forsythia, mock orange (Philadelphus), caragana (Caragana spp.), ninebark (Physocarpus opulifolius), honeysuckle, and double-flowering plum. If you spot broken, diseased, rubbing or winter-killed branches any time of year, however, prune them back to a suitable place below the problem area as soon as you can.

Don't trim shrubs with hedge shears to produce rounded heads. That sort of geometric pruning might work for cedar or yew, but it spoils the natural look of a lilac, removes flower buds and encourages branching at the top of the plant. Also, don't remove all the low branches and those that arch near the ground so that a mower can be run up to the base. The former removes all your new wood for potential flowering. The second practice destroys the natural shape of the shrub. Grass usually won't grow in such a shady place anyway, but if you do need to mow under the branches, raise them first. Alternatively, clear away the sod, and put down mulch or plant a low, shade-tolerant groundcover.

Remove new shoots (suckers) that grow from below the graft of grafted plants. Generally, the foliage will look different-probably smaller-than that of your desired variety. If you leave the suckers until they flower, you will have more than one type of flower on your plant, and the below-graft shoots may eventually dominate the shrub.

COMMENTS

Back To Top