When to Cut Perennial Plants Down | Gardening Advice

Wondering when to cut perennial plants down? Read on for our expert advice.

Many perennial gardens in New England are beautiful in autumn, but most find that these flowerbeds are a mixed bag in the fall. There are plants such as asters, mums and Montauk daisies that are in full bloom. Some perennials, such as Ajuga, are past bloom but still have attractive foliage into winter, and others are attractive even as they die back and turn brown. We enjoy the ornamental grasses for a number of months, for example. But there are many perennial plants that are no longer thriving and beautiful. So what’s a gardener to do? The good news about fall perennial garden maintenance is that there is not one right way. Some want all their plants cut back to the ground early in the fall so that they can cross this off their list. Others clear out perennial plants as they die back, leaving those plants that are attractive in the garden as long as possible. And there are those gardeners who decide to leave all perennials in the garden until spring. There are advantages and drawbacks to each of these approaches. If you are the “let’s get this garden cleared up now” type, go right ahead and cut all your perennial plants down in October. Leave about 2” of stem above the ground so that it’s easier to see where late-emerging perennials are located in the spring. The only exception to this approach is with plants with woody stems or newly planted perennials. Woody plants such as Russian sage and lavender don’t get cut down in the fall. Lavender is treated as a small shrub, and sheared in the spring, and Russian sage will get cut down by half or more once you see how much of the old stems survived the winter. Newly planted perennials seem to survive their first winter better if left as is until spring. This may be because their stems catch leaves that provide insulation. For some plants with thicker stems, energy may be stored there that helps the plants to survive the winter. But in any case, leaving those intact and then clearing them out in the spring helps with first-year winter survival. If you are someone who enjoys seeing attractive foliage and late-flowering plants in the garden as long as possible, clear your garden on a plant-by-plant basis. I suggest the following rhyme to help you remember which plants to leave: If it’s brown, cut it down. If it’s green it must be seen. There will be some perennial plants you cut in October, but others that will look good through much of the winter. Finally, some people decide to avoid the fall cleanup altogether. A friend of mine leaves everything in her garden because, she says, “Snow needs something to fall on.” Others know that beneficial insects often over-winter in the leaf litter and debris, and they want to encourage the butterflies and bugs that do so. Birds eat seeds off of perennials all winter, and in the early spring the winter-worn foliage provides early nesting materials. So whether you’re in the mood to just get it done, or whether life is so busy this fall that you don’t get around to putting your perennial garden to bed, know that all approaches work. What’s your method for dealing with perennial plants in the fall? This post was first published in 2016 and has been updated. 

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