Fall Pruning TipsSeptember 25, 2015
Have you been duped into believing fall pruning is ideal? Surprise! Fall is one of the worst times to prune. Or at least, it’s the worst time to prune most woody plants. There’s plenty of other cutting and cleaning work to do instead.
Put down your saw this time of year and spend this time weeding, raking, mulching and cutting back perennials ready to hunker underground for the cold months ahead.
Why not cut woody plants now? Making cuts on plants does a number of things to their growth systems. Trimming can stimulate new growth, and new growth is tender. If a cold snap hits, which can happen unexpectedly and fast anytime in fall, any tender new shoots can be damaged, weakening your plant and making it look awful. That being said, if your shrubs have been neglected for a long time and are full of dead material, go ahead and snap the dead stuff out. Just don’t start sawing on living limbs at this time of year.
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Have happy hedges! You know those hedges that look raggedly and full of holes all winter. Maybe they die out in spots as winter trudges by? Most likely they were cut hard in autumn. Instead, save shearing work for late winter, early spring or even mid-summer. Trimming hedges just ahead of the spring growth surge ensures they’ll flush out with lush, privacy-providing new growth fast; trimmed in mid-summer, they’ll put on a little regrowth with time for it to toughen up for the cold season and look tidy as well.
Wait! What about winter bloomers? Prune these only as they’re blooming or shortly after. If you trim a winter-flowering hedge or shrub after early spring, you’ll cut off all it’s flower buds for the winter to come!
If not trees and shrubs, What should you be cutting in fall?
Stick to herbaceous perennials. These are plants that sprout from the ground each spring, leaf out and bloom during spring, summer and early autumn only to retreat into the soil to live through the winter. They do not have woody stems. While they do not really die each fall and winter, their top growth does whither and disappear during fall. Examples include bleeding hearts, columbine, Japanese painted fern, peony (not tree varieties), phlox, black-eyed susan, Solomon’s Seal, Japanese forest grass, hostas, Astilbe, Miscanthus and more.
Should I just raze the earth of perennials in autumn to tidy things up? No! Avoid cutting back perennials that don’t completely disappear underground in winter such as hellebore, Brunnera, Heuchera, deer fern, Bergenia, Epimedium and sword fern. And, hold off cutting late bloomers like asters, late-flowering sedums and monkshood or you’ll miss their showiest times.
Don’t forget about the wildlife! If your perennials have seedy flower remnants or berries and hips, let the birds forage them clean before you trim. And, leaving some leaves unraked, twigs unpruned, spider webs unbroken and other “messes” builds habitat for the wild birds and bees every garden needs.
And, just to confuse things a bit more: Some plants cross the line between herbaceous and woody perennials. Hardy fuchsia is one of the best examples. Most fuchsias bloom into late autumn, or until a frost hits them, so leave them be early in fall. Once they do get hit by a chill, you may choose to leave some varieties like F. magellanica standing tall to show off its peely bark. Or, cut it hard to refresh the growth when it is ready to arise again in spring.
Did we miss something? That wouldn’t be surprising. Pruning can be tricky and complicated. And while we’ve covered some basic rules here, rules are made to be broken…or at least fine-tuned and modified to go with all the complicated life forms that reside in our gardens. Share your challenging issues via the comments below or get in touch to schedule your in-person Garden Mentors consultation session for customized gardening guidance that’s just right for your garden!