Although I had never been an advocate of a large scale cleanup in the fall garden, this year has found me in a different frame of mind. For some reason it all looked so tired, so messy, this fall. I don’t know whether it was a result of the hot, dry summer, or if my ‘horticultural slackness’ during the latter part of August and into September may have contributed to the disarray I was subjected to on a daily basis.
I am always asked in the fall whether one should trim or leave perennials alone for the winter. For novice perennial gardeners it’s difficult to know whether to trim or to abstain. I’ve generally left all my perennials alone in fall, reasoning that their stems will catch leaves or snow, and provide a bit of extra winter protection. But it certainly doesn’t do much for the appearance of the garden in winter. If you look up the word “disheveled” in the dictionary it is defined as “Scott’s garden during the winter months.”
So, I’ve decided to trim away this year, and I’m glad I did. The garden looks much neater, and there will be less to do next spring, perhaps four truckloads of compost material instead of six! If you’re of a like mind, and want to take the pruners or hedge shears to all the dead and bare stems here are some guidelines.
Ornamental grasses generally look great right through winter, so I wouldn’t do anything with them. Their flower heads provide motion in the wind, and the foliage, even though it may turn to a tan colour with the frost, remains attractive until next spring. An added bonus to living in the Okanagan is that the snow is generally quite dry, so it doesn’t sit on top of the grasses, bending them over and making them look beaten down.
Some perennials spring up from a rosette of foliage right down at ground level. Heuchera, Euphorbia, some Sedums, Salvia, Coreopsis and many others fall into this category. The upright leaves and stems can be cut back, but leave the lower leaves until next spring, when you can give them a quick trim as you see new growth emerge from the ground.
There are many perennials which have evergreen foliage through the winter, including several rock garden plants like Arabis, Aubretia, Iberis, Cerastium and Dianthus. These should be left alone in fall; the best time to trim these is right after they bloom.
Woody-stemmed perennials like Perovskia, Lavatera and Caryopteris can be trimmed back a bit in fall, just to clean them up, but save the main pruning until early spring. With Perovskia, the Russian Sage, I find that taking off about half of the unruly stems in fall makes it much easier in spring, when I cut them down to about eight inches above ground level at the time when you can see the new growth shooting out of the bare wood.
While you’re out trimming in the border take the time to pull out any weeds that may still be lingering, particularly annual weeds that have set seed. Again, it will be one less job come spring.
If you haven’t done any of these tasks yet and it appears that winter has arrived to stay, don’t despair. We’re sure to get some warmer days ahead where it will be quite pleasant to do some cleanup work in the mid-day winter sun.

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