Have you been duped into believing fall pruning is ideal?
Surprise! Fall can be one of the worst times to prune. Or at least, it can be the worst time to prune woody plants. And there are many plants that you should not prune in fall. But, rules are made to be broken. So be sure to read the details before you decide if it’s time to prune your plants in fall or not.
Why is fall pruning often not a good idea?
Fall pruning can be detrimental to many plants. Especially if you start cutting plants at the start of fall rather than later in autumn.
But to know why, let’s consider what happens when we prune.
First, making cuts on plants does a number of things to their growth systems. For instance, trimming can stimulate new growth. And new growth is tender.
So if you do fall pruning and your cuts stimulates new growth, your plant is more likely to sustain freeze damage. 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. But don’t start sawing on living limbs at this time of year.
Is fall pruning always problematic?
No. In fact, once your plants have lost their leaves and have been standing bare for at least a couple of weeks, that’s the time to begin many woody pruning jobs. That’s because at this point in the season you’re unlikely to stimulate new growth! Why no new growth stimulation? The plants have entered dormancy and “know better” than to put on new growth at this point.
What about trimming hedges in fall?
You know those hedges that look raggedly and full of holes all winter? Maybe they die out in spots as winter trudges by? This is most likely because these hedges were cut hard in autumn.
A better choice is to save shearing work for late winter, early spring or even mid-summer. In fact, trimming many hedges just ahead of the spring growth surge is ideal. This may help them flush out with lush, privacy-providing new growth fast. On the other hand, when hedges are trimmed in mid-summer, they’ll put on a little regrowth. And, in most situations, that little bit of new growth will have time for it to toughen up for the cold season and look tidy as well.
Should I prune winter bloomers in fall?
No! Prune these only as they’re blooming or shortly after. That’s because 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. So fall pruning isn’t good for winter flowering woody plants.
Is fall pruning good for non-woody plants?
Many herbaceous perennials can be trimmed to the ground in fall. To clarify, 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. So 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 of perennials for fall pruning 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.
However, keep in mind that wildlife may be relying on those “ratty looking” perennials to stay put through winter. So cleaning up by cutting them back may not be the most eco-friendly gardening option.
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.
Again, don’t forget about the wildlife when you prune in fall!
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. Plus, many insects need these stems to over-winter or for their eggs to over-winter. So, sometimes leaving withered perennials stems standing helps wildlife too.
And, just to confuse things a bit more:
Some plants cross the line between herbaceous and woody perennials. So you may be unsure about pruning them in fall.
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.
Still need more help with your specific fall pruning challenges?
Finally, if you’re looking for help pruning specific plants, try using our search. That’s because you’ll find several library articles here covering when and how to prune plants like rhododendrons, strawberry trees, and more.