Cleaning Up
Do fall yard and garden work in stages
By Rachel Foster

What a glorious fall we’ve had this year, and I am not just referring to the election. The crapshoot that is Oregon weather brought not only great wine grapes and an embarrassment of apples and pears to the Willamette Valley but also fall color like we haven’t seen in decades. As November approached and I marveled at the colors in the wider landscape, I also appreciated the smaller, subtler effects in my own garden as perennials, shrubs and grasses prepare for dormancy. 

Like many flower gardeners, I’ve concluded there is too much to lose from cutting down and removing a whole season’s biomass in an October clean-up. Particularly this year. After a brief period of chilly but (at least here in town) frost-free nights, the weather has turned mild. What isn’t arrayed in yellow or scarlet is still fresh. Some ornamental grasses are still green and vibrant, while anemones, fuchsias, dahlias, cannas and the occasional rose provide mementoes of summer glories.

Late color isn’t the only thing we sacrifice in the name of clean-up. Beetles and spiders overwinter in cozy perennial clumps, and birds enjoy foraging for seed; a layer of coarse organic debris prevents compaction from rain. All the same, most of this detritus must go to the compost heap eventually, and there are both horticultural and esthetic reasons for doing it sooner rather than later. 

Fallen leaves left lying on evergreen plants can result in bald spots. Diseased foliage on roses and irises and rotting, rain-soaked blooms increase your garden’s bank of fungal spores. A few plants, notably kniphofias and some irises,  are easier to cut back before they rot, while others look just plain ugly beyond a certain stage of decomposition. 

A bit of clean-up makes it easier to plant bulbs in perennial and shrub borders. It also makes a more attractive setting for emerging bulbs in early spring and may help keep you out of sensitive beds in February, when the ground is wet and the emerging snouts of bulbs are especially vulnerable. 

If you do go in for clean-up and prefer to do it in stages, what should be your priorities? Starting in the areas you see most often, clean up around small evergreen shrubs so you can actually enjoy them. They will also benefit from more light and improved air circulation. Remove seedheads from things that self-sow wildly — it will save work later. Clean up diseased foliage and any frosted plant tops. Mulch exposed soil wherever possible. 

Care of ornamental grasses can be confusing because they vary so much in their life cycles. Some change color rapidly in autumn and then collapse. Clean these up any time. Some adopt fall colors gradually and remain standing well into the new year. Cutting them down now won’t hurt them, but as long as you like the way they look, let them stand. Just remember that if you leave the clumps uncut much after January new growth will make the job a lot more difficult. By the way, I belatedly tried that trick of tying the tops of taller grasses in a bundle before cutting. It certainly makes for a neater job. 

 What about grasses that remain green, bronze or gray all winter? Some of these may be damaged by cutting back in fall. Leave them alone until next spring, when you may find you can remove old blades with a combing action or a sharp tug on a few blades at a time. Sedges can be deciduous or evergreen, and the latter resent being cut down in fall. Cut them to the ground in spring, when they already show signs of new growth. Other things to leave alone in fall and winter include New Zealand flax (phormium) and semi-hardy shrubs like lavender, rosemary and plumbago, and almost anything with silver foliage. 

The ever-popular butterfly bush (Buddleia davidii) is seriously invasive when it escapes into natural areas. If you grow buddleia, you should deadhead it. Since this brittle and often overbearing shrub is best treated like a giant perennial, it would seem simplest to prune it back to a couple of feet in fall, killing two birds with one stone. Unfortunately, buddleia is another of those things that may sulk and even die if it is cut back hard in fall, so I was interested to learn a while back that it does not release its seed until late winter. 

Late winter is the usual time to prune buddleia, and the Forest Service official who told me about this claimed he can trace the popular routes to yard-waste recycling yards by the copious butterfly bushes that grow along the way! He suggested cutting plants back part way in fall and discarding the seedheads before the seed shakes loose. In early spring,  complete the pruning job by cutting back to a low framework of major
branches.

Rachel Foster of Eugene is a garden consultant and author of All About Gardens, a selection of past EW columns. She can be reached at rfoster@efn.org