How to Prune Lilacs and Rhododendrons

When simply deadheading isn’t enough, here’s how to prune lilacs and rhododendrons that have become too tall.

By R. Wayne Mezitt

Apr 28 2008


Photo Credit : Denise Torres
Every spring I remove the faded blossoms on our lilacs and rhododendrons after they’ve finished flowering, to help them bloom better the following year. Now the plants are getting too tall to see the flowers well. What do you recommend for pruning lilacs and rhododendrons? — E.W., Boylston, MA Removing spent flowers — called “deadheading” — is a good idea for many plants, including lilacs, rhododendrons, and mountain laurel. Not only does it keep them tidy, but it also lets the plant devote its energies to producing new growth and flower buds rather than to developing seed. Pruning lilacs and rhododendrons right after they finish blooming is best when they grow too big for us to enjoy their flowers. Cutting them back removes the old flowers and also lowers the tops for a better view. Do it in late spring to allow plenty of time for new shoots to grow and for next year’s flower buds to form. Pruning lilacs that have grown too large for your area may be done over several years, cutting back a third to half of the stems each year. Suggestions, please, on pruning and mulching gooseberry bushes. — W.B., Willow Street, PA Gooseberry (Ribes grossularia) is an underutilized and very productive fruiting plant, well suited to the home garden. Thorny, winter-hardy to Zone 3, and low-maintenance, gooseberry cultivars are easy to grow in almost any soil as multistem shrubs or single-stem plants. To simplify maintenance and harvest, train your plants to a cone shape growing from a 6-inch-high single stem, called a “leg.” The first spring, start developing the framework by cutting back, to about 6 inches, the three or four most vigorous shoots growing from the top of the leg. Remove all other shoots. Early next spring, again cut back the three or four most vigorous shoots growing from the top of each of last year’s stems, and remove all other shoots. Thereafter, remove weak shoots and crossed branches each spring. Removing and shortening stems produces smaller crops with larger fruit — easier to pick. Gooseberry plants benefit from a 2- to 3-inch-thick layer of mulch to insulate their shallow roots, maintain moisture, and minimize weeds; refreshing it each year is a good practice. Lee Reich’s fine guide, Uncommon Fruits for Every Garden (Timber Press, 2004; $24.95), describes numerous unusual fruiting plants and includes a chapter on gooseberries.