Putting your Colorado garden to bed for the winter

Autumn weather so far is resembling summer, other than the brief cold snap last month.

Along with recent 80-degree days, there are dangerous fires still burning in parts of the state. The city of Fort Collins is on water restrictions because of drought, the Cameron Peak fire and the maintenance project on the Horsetooth Reservoir.

Next week, temperatures should cool to the 60s with little to no moisture relief in sight.

Will sweater and parka weather arrive soon? Your guess is as good as mine. It is Colorado, after all, and winter can arrive any minute, impolitely skipping a gradual cool-wet fall season that gardeners and landscape plants prefer.

Let’s all make the best of it: Get some exercise outside on these beautiful October days and put the landscape to bed properly.


Our landscapes are dry. We’ve had only one moisture-producing storm of late along the Front Range. (You remember Sept. 8 and 9, when it snowed and gardeners quietly cursed.) For an already dry region that only receives roughly 15 inches of precipitation yearly, we are currently at 7½ inches. Nature has some catching up to do.

Landscape plant roots absolutely need to be moist going into cold weather prior to the ground freezing. Dry roots can spell disaster for perennial plants that went in the ground this past spring, summer or last week. Dry tree roots, coupled with lack of winter moisture, can lead to root and branch death, less foliage, scorched foliage, no foliage or no tree next year.

If you are unsure if your landscape is dry, the simplest way to assess is to poke a screwdriver straight down in landscaped areas, like mulched beds, lawns and around trees. If it goes down easily, you’re probably not too dry. Conversely, if you’re using a bit of effort, there’s your answer.

Water all plants weekly until temperatures remain below 40 degrees and decent rain and snow arrive. Water deeply so all landscapes plants enter winter with adequate soil moisture. Trees need to be watered to a depth of 12 inches. For all other landscape plants, apply water so that the plant itself, and close-by surrounding soil, is moist to a depth of a couple of inches (not wet, but moist). A 2- to 4-inch layer of organic mulch like shredded bark or chopped leaves mixed with chemical-free lawn clippings are readily becoming available as trees shed leaves and you’re still mowing.

If you are new to Colorado, winters can be bone dry for long stretches. That means you need to drag out the hoses and give every plant another deep drink or two between snow events.

Garden cleanup

It is a gardener’s choice whether to cut back ornamental perennials with dead foliage in the fall or spring. Plants receive additional insulation and protection from our frequent freeze/thaw winter cycles when foliage is left in place. Snow-covered foliage can also add interest during the winter months. Birds appreciate seed heads and using the foliage for screening.

Any recent spring- or fall-planted perennials and shrubs should not be cut back in the fall.

Do not cut back woody plants, including butterfly bush, culinary sage, lavender and other late-summer or fall-blooming plants. Established perennials that may have had a disease like powdery mildew or harbored pest insects can be cut back in the fall, including plants like bee balm, phlox, salvia and Japanese anemone.

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