Gardening Advice: Overgrown Shrubs

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Gardening Advice: Overgrown Shrubs

October 3, 2001
08:16am

Q: Our prewar house is crowded by overgrown lilacs, bridal wreath spirea, mock orange, and forsythia, which flower little, if at all, and seem to be choked with dead wood. Is there any way to nurse them back to ornamental health? — Frances Anderson, Oskaloosa, Iowa

A: Your lackluster shrubs are a pruner’s dream. A sturdy pair of bypass pruning shears, a small but sharp pruning saw, loppers, and a few pleasant days are all that’s needed. Late winter is the ideal time to tackle this satisfying job: no leaves obscure the framework of the plant, the roots have plenty of food stored for resurgent growth come spring, and the gardener has a strong case of cabin fever. Along with the old-fashioned spring-flowering Weigela, Deutzia, and beauty bush (Kolkwitzia amabilis), the shrubs you mention are all exceptionally tough, vigorous plants. It’s understandable, though, why in some circles they’ve fallen out of style. They put out canes — long, sparsely branched stems — that tend to grow weak and unkempt with age; they usually bloom only for a couple of weeks; and landscapers overused them during the first half of this century. But there’s no good reason why mature specimens don’t deserve a second chance, and they can easily be rejuvenated to attractiveness in just two or three years.     

Remove approximately one-third of the branches — the oldest, twiggiest, and weakest — at the base, and cut a third of the remainder back to a strong fork or outward-facing bud. Repeat the process the following winter, taking out another third, or — if you’re getting really impatient — the rest of the old wood. If you go crazy and chop the whole bush to the ground the first year, it will survive, though only by sending up an overabundance of spindly suckers. Also, with these spring-flowering shrubs, keep in mind that whatever wood you remove in late winter will cost you in flowers; but since you’re not getting much bloom anyway, it’s a wash. Once a shrub is flourishing again, cut off one or two of the oldest canes every few years, right after flowering, to keep the plant in good shape.   

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