What to Prune Now, and How

It’s pruning time, y’all! At least for roses and shrubs that bloom mid-summer or later.  And pruning is the most important gardening task that most people never do.  Or if they do prune, they do it the old-fashioned way – by shearing plants into perfect shapes.  But these days shearing is discouraged in favor of a more naturalistic style that’s better for plant health and requires less frequent pruning by the gardener.  And to my eye, plants allowed to look natural are just prettier.

This healthier method of pruning is called renovation or renewal pruning because it prompts the plant to grow new stems from the base rather than masses of new leaves at the outer edges of the shrub, where they form a shell that prevents air and light from reaching the inside. The following are shrubs that are most in need of this type of pruning, which should be done soon – between now and April 1.

Butterfly bush and Caryopteris should be pruned now.

Butterfly bush and beautyberry should be chopped to within 3 or so inches from the ground. Nandina needs its tallest, leggiest stems cut back to near the ground.  For cherry laurels, euonymus, privet, photinia and summer-blooming spireas, remove one-third of the stems to the ground, choosing for removal the tallest and oldest and the ones that are crowding the interior.  That’s in addition to removing any dead, diseased or broken stems or branches. Roses need yearly pruning and most of them need it in March, but how and when depends on the type, as explained here by Homestead’s guru Gene Sumi.  (Photo below shows Gene’s pruning work on a Knockout rose.)

Shrubs in hedges may need to be sheared in order to be kept narrow enough for their site, but they still benefit from having up to a third of their oldest stems removed.  Then if the outer edge is thick and blocks light from the interior, use a hand pruner to punch holes in it.  That will encourage growth on the inside while improving the air circulation that helps prevent disease.

There’s another group of shrubs that should be pruned now, but only if they really need it, which they may not.  Two that are often pruned – late-blooming hydrangea (like Annabelles and H. paniculatas like ‘Limelight’ and ‘Tardiva) and crape myrtle – don’t need regular pruning at all, unless they’re too big for where they’re planted.  Here are more evergreens and summer-bloomers that can be pruned now: abelia, boxwood (through July is fine), clethra, cotoneaster, redtwig dogwood,  gardenia, hibiscus, St. Johnswort, and osmanthus

Why now? Winter is the best time to prune most trees and many shrubs because it’s when they’re dormant.  And for the leaf-dropping types, it’s when you can better see what you’re doing.  Just don’t prune spring-bloomers now if you’d like to enjoy those blooms this season; wait until the blooms have faded.  (Evergreens can be pruned any time from December through August.)

Prune forsythia after they bloom.

So in late spring, give these spring-blooming shrubs this seemingly drastic treatment and they’ll thrive – I promise.  Yes, you’ll be removing huge amounts of plant material, but be brave!  Forsythia should be chopped down to the ground or close to it.  For azaleas, weigelas, viburnums and spireas, remove one-third of the stems to the ground.  Rhododendrons don’t suffer from overcrowding like the others in this group but may still benefit from renewal pruning if they’ve become top-heavy or otherwise misshapen.

Before you grab your tools, just one more tip about pruning.  Make the cuts just above a node or branch, about 1/4 to 1/2 inch away.  That way, unsightly, unproductive stumps aren’t left hanging, and cuts are made where they can generate the most new growth – at those nodes where the growth hormones are.  The tools you’ll use are: hand pruners, loppers and folding pruning saws.

To learn more, just Google “prune X”, X being the name of the shrub, and click on the links that end in “edu” or “gov”. For more visual help, do the same at Youtube.com.

Forsythia photo credit.

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