Around the Garden

Notes From/To a Negligent Gardener

From my living room window, I can see the twelve-foot-tall spires of a Rose of Sharon, flowering only at the very top. Why is my Rose of Sharon not covered in blooms, as my neighbors’ shrubs are? Likely because it’s smashed up against an equally vigorous Japanese Pieris and an Oak-leaf hydrangea that has expanded like a Saint Bernard pup on steroids. All three shrubs could use more sun light, but they each have to make do with about one-third of their daily quotient.

What to do, what to do? Pruning is, of course, the answer, but the scary question with flowering shrubs is always when to do it. First, let’s distinguish deadheading from pruning. Cutting some flowers to bring indoors is not pruning, nor is removing spent blooms. Pruning refers to redirecting the growth of a branch, or reducing the size of the entire plant.

This is not to say that you shouldn’t snip judiciously at all times, however. ALWAYS cut woody stems back to a healthy twig or node (bud) that’s growing in the direction you want the new growth to go in. If you leave a length of stem that has no buds on it, you will have a section of dead wood that can introduce disease into the rest of the plant. Woody plants have specialized tissue at nodes to help heal over any cut that you make.

Cutting flowers is a good idea now, as it will encourage formation of new flower buds. Pruning is not so good: depending on the plant, you might stimulate a flush of new growth that will not harden in the fall. When frost and snow hit, that tender growth is likely to die back, and you have just wasted a lot of the plant’s energy.

The usual rule is to prune spring shrubs right after flowering, and fall-blooming shrubs in

late winter to early spring. Buddleia is a great example of a plant that is happiest if cut back very

hard in late March or early April. Many of the blue-gray foliage plants should be cut back just as soon as a couple of new leaves appear in early spring: lavender and Russian sage will be much bushier and more vigorous as a result. Cut just above the base, leaving a little of the new foliage, and your new plant will thrive.

And what about the truly woody late

summer shrubs? Some of them need to be shorn just to encourage flowering. Callicarpa, or Beautyberry, is a good example of a shrub that will reward hard pruning in early spring with a much improved show of flowers and dazzling purple berries. (Some recent articles claim that Beautyberry in the garden is a natural defense against mosquitoes and ticks. I hate to think what my garden would be like without it!)

Another good reason to prune hard is to discourage flopping. My huge mass of Clethra alnifolia (Summersweet) collapsed from its own weight onto a perennial bed this year. The Clethra is still covered in sweet-scented flowers – the common name is accurate – but the perennials are buried alive.

One final note – shrubs are very different from trees. Trees will die if pruned hard – with the possible exception of the Norway maples that sprout and resprout endlessly in my garden!