Centennial Before the Freeze: What to Save, What to Cut and What to Leave Alone

There comes a point every autumn in Centennial when we begin playing a familiar Colorado game.

The afternoon is sunny and warm enough to make you wonder whether summer actually left. Then you check the overnight forecast and suddenly there is a 32 staring back at you.

Welcome to frost season.

For gardens in 80015, that first stretch of freezing nights does not mean everything outside needs to be chopped down, pulled out or hauled to the trash. In fact, some plants need protection, some need to come indoors, and quite a few are better off if we simply leave them alone.

Here is your Centennial pre-freeze checklist.

1. Decide What Is Worth Saving

Not every flower needs an emergency blanket.

If you have annuals that are still thriving and giving you plenty of color, a little frost protection can extend their season. Colorado State University Extension recommends using coverings such as sheets or blankets during light frost conditions. Remove those covers during the day so sunlight can warm the soil again.

Containers are particularly easy to protect. Move smaller pots into the garage, against a protected wall or under a covered patio overnight.

And don't assume every colorful annual will collapse at the first frosty breath. Pansies, violas and snapdragons are among the cold-tolerant flowers commonly grown in Colorado. Nick's Garden Center specifically lists these among its frost-hardy annual selections.

So before holding a midnight funeral for your flowerpots, check what you actually planted.

2. Bring the Tender Crowd Indoors

Houseplants that spent summer vacationing on the patio need a change of address.

Bring tropical plants and other tender container plants indoors before temperatures become too cold for them. Check the pots, leaves and undersides of foliage for insects first. Nobody wants to accidentally establish an indoor aphid resort.

Give plants a transition spot with appropriate light and expect some adjustment. The move from bright Colorado sunshine into the house can be significant.

This is also the time to decide whether certain tender plants are worth overwintering.

Dahlias are a good example. Nick's notes that dahlia foliage does not tolerate frost and recommends allowing frost to kill the vegetation before preparing the tubers for winter storage rather than relying on them to survive Colorado winter conditions in the ground.

3. Put Down the Pruners

Here is where our tidy instincts can get us into trouble.

Brown does not automatically mean "remove immediately."

Arapahoe County's Colorado State University Extension recently reminded gardeners that leaving perennial stems and ornamental grasses standing through winter can provide real benefits. Stems can trap snow and leaves around the plant crown, helping insulate roots from Colorado's freeze-thaw cycles. Seed heads on coneflowers, black-eyed Susans and other perennials provide food for birds, while hollow stems may offer winter habitat for beneficial insects.

So that slightly shaggy perennial bed?

It may actually be doing important work.

Cut back diseased or pest-damaged material, but healthy plants do not need to be scalped simply because the calendar says fall. CSU also recommends reducing fall perennial cleanup when possible to support pollinators and wildlife.

Think less "clean everything" and more "edit thoughtfully."

4. Don't Forget the Water

The sprinkler system may be approaching winter shutdown, but your landscape has not stopped needing moisture.

Colorado's fall and winter conditions can be extremely dry. CSU Extension recommends supplemental watering for trees, shrubs, lawns and perennials during extended dry periods when air and soil temperatures are above 40°F and there is no snow cover.

This is especially important for:

• newly planted trees and shrubs

• evergreens

• recently established lawns

• exposed perennial beds

• shallow-rooted trees

Water during the warmer part of the day so moisture can soak into the soil before temperatures fall again.

A tree going dormant is not the same thing as a tree suddenly becoming capable of living without water.

5. Leave Some Leaves

The leaf blower does not have to win every battle.

Leaves covering sidewalks, driveways and thick sections of turf should be removed, but leaves tucked into perennial beds can become useful natural insulation and habitat.

That does not mean burying the yard under six inches of soggy maple leaves.

It means recognizing that a perfectly sterile garden is not necessarily a healthier garden.

Nature has never been particularly interested in winning a neighborhood landscaping award.

6. There Is Still Time for a Nick's Run

If you are unsure what should be protected, planted, stored or left standing, Nick's Garden Center & Farm Market remains a terrific nearby resource for Centennial gardeners.

Fall also happens to be one of the liveliest times at Nick's. Its 2026 Fall Fest runs through October 31 and includes pumpkins, gourds, cornstalks, seasonal décor and family activities in addition to the garden center. Entry is free, with separate charges for certain rides and attractions.

Nick's Garden Center & Farm Market
2001 S. Chambers Road, Aurora
303-696-6657
Visit Nick's Garden Center

You might go in for frost cloth and leave carrying a pumpkin.

Colorado autumn has rules.

A Better Kind of Fall Cleanup

The goal this time of year is not to make the yard look finished.

It is to help the landscape enter winter healthy.

Protect the tender plants. Bring in what cannot handle the cold.

Water when Colorado stays dry. Remove diseased material. Let healthy perennials and grasses provide winter structure. And give yourself permission to leave a little bit of nature exactly where nature put it.

Because in a Centennial garden, sometimes the smartest fall chore is the one you decide not to do.