When (and how) do Denver-area gardeners get prepared for winter? The first fall frost usually arrives here in the first half of October, giving high-country Coloradans plenty of time to tidy up their gardens and put them to bed until spring. Grab your calendar—here are the most important items on your fall gardening to-do list!
1. Remove fallen plant debris
Annual plants die off at the end of the growing season, and many perennials drop their leaves or turn brown as they go dormant for the winter. Allow bulb Clean up any mushy debris—including decaying fruits and vegetables—that can cause root rot, attract pests, or detract from your landscape’s aesthetic.
Destroy hand-pulled weeds and diseased leaves and stems—never add them to your compost pile.
2. Add soil amendments
If you add soil amendments to your garden in late summer or fall, your soil ecosystem will be primed and stabilized for early spring planting. Fall soil conditioning also raises the accuracy of spring soil tests, after which you can make fine adjustments if needed.
Need help testing your soil for proper pH and nutrients? Country Fair Garden Center sells home testing kits, or you can pick up a soil sample kit at our Denver store. Follow the easy instructions, bring your soil samples to us, and we’ll forward them to Colorado State University’s soil testing lab for the most accurate results. Then let us help you select the products you need to balance your soil!
3. Divide early-blooming perennials
Mature perennials get “crowdy” after a few years, requiring them to be separated the root ball. Early fall is the ideal time to divide spring and early-summer bloomers, most notably iris, lily, hostas, bleeding hearts, and other bulb or tuberous species. Colorado State’s Plant Talk blog has excellent advice for dividing spring-blooming perennials grown in our region.
4. Protect container-grown patio plants
Potted perennials are less insulated than plants grown directly in the ground. Move your dormant container plants into a shed or garage where they’re less likely to experience extreme temperature fluctuations. Some herbs do well in a sunny room or windowsill, allowing you to enjoy fresh flavoring through the winter!
5. Prune or cut back plants
Find out which of your shrubs, trees, and herbaceous perennials require sprucing up in the fall. A bit of pruning here and there will encourage vibrant regrowth in the spring, reduce damage from winter breakage, discourage pests and disease, and increase airflow among branches. Remove any spent flowers or developing seed pods if you want to avoid self-seeded “volunteers” in the spring.
- Keep your pruners sharp, and wipe them down with alcohol before you move on to the next plant or tree.
- Wait for plants, trees, and shrubs to go dormant before pruning.
- Remove spent stalks and flowers from late-season bulb plants as they lose vigor, but hold off on removing the leaves until they lose their green or begin to wilt.
- Many herbaceous perennials grow back fuller and produce more flowers if they’ve been cut to the ground the previous fall.
6. Mulch to protect your soil and insulate more sensitive plants
Good news! You’ve got a use for all those fall leaves! Cover your empty garden beds with a layer of leaves or packaged mulch to reduce soil compaction and erosion. In the spring, you can rake up and compost whatever mulch hasn’t decayed, or just move it to the side to make room for new transplants.
Some perennials do best with an insulating layer of mulch around their bases or over their crowns, but no matter the season, we recommend leaving at least an inch between exposed plant stems and your chosen mulch to prevent fungal diseases.
Important tip: If you decide to mulch with seed-free grass clippings, wood shavings, straw, shredded leaves, or compost, be sure you only source herbicide-free materials. Residual chemicals from weed control products can damage your garden plants. Getting manure from a local friend or your chicken coop? Herbicides used to treat hay and straw can survive both the digestive process and the composting cycle. It’s a good idea to use packaged manure, mulch, and potting soil from your nursery.
7. Winterize your irrigation system
Nobody wants to celebrate spring by digging out burst sprinkler lines! Use an air compressor and appropriate fittings to “blow out” shallow irrigation systems before the first hard freeze, and drain flexible micro-irrigation tubing. Consider removing and cleaning drip, mist, and bubbler emitters to avoid damage and dirt infiltration. You’ll want to flush out the lines before popping those emitters back in in the spring.
8. Prepare for late winter tree care
Many ornamental and fruit-bearing trees require pruning in late winter dormancy when they’re less vulnerable to insect damage and disease. Autumn is an ideal time to select branches for removal. If you’re new to tree care, you’ll have time to consult with your gardening pro or arborist. That way, you’ll have greater confidence and motivation when it’s time to haul out those loppers!
9. Plan next year’s garden
Now that you’ve prepped your landscaping and vegetable beds for winter, take some time to think about what Colorado-friendly plants and projects you might want to tackle next year. Winter’s a great time to research new plant species, scroll through Instagram and Pinterest for creative gardening ideas (especially for small backyards!), and shop for garden accessories that make routine landscaping maintenance fun and easy.
Gardening is easy when you’ve got experts on your side!
We hate to use the term “chores” when we talk about seasonal gardening projects. That’s because, like our loyal customers, we love playing in the dirt and watching our plants thrive as a result of easy, routine maintenance tasks. Don’t worry about taking on each of these essential projects in a single weekend—there’s plenty of time between now and just after Denver’s first hard frost to get things done.
And if you need help any step of the way, contact us or come into our Denver store. We’ll help you along the path to success with your Rocky Mountain garden!