Fall Work - Cleaning up Your Perennials
Apparently snow is in the forecast, and if you haven’t already, you may be wondering when it’s safe to clean up the above-ground parts of your perennials. Continue reading to find out when it’s safe to clean-up your perennials in the fall, and why it’s important to wait till the right time.
When to Clean Up Your Perennials in the Fall
With the gardening season winding down in southwest Saskatchewan and temperatures drop (many areas have received a frost), you might be thinking about cleaning up their perennial beds (if you haven’t already). While it’s tempting to get everything tidy before winter hits, timing is important. Knowing when and how to clean up your perennials can ensure their survival through our cold winters.
Here’s a guide to help you decide when it’s safe to start your perennial clean-up and what factors to consider.
Why Timing Matters for Fall Perennial Clean-up
Perennials are plants that die back to the ground in the fall, but their roots remain alive beneath the soil. These roots need protection through winter, and cleaning up too early or too aggressively can jeopardize that. When perennials finish their growing season, they pull nutrients from their leaves and stems into their root systems. This helps them store energy to survive winter and regrow in spring. Premature cleanup can rob them of those nutrients and compromise their winter hardiness.
For gardeners in Zone 3, where winters can be harsh, the key is to wait until the perennials are truly done for the season. Cutting back too soon can expose plants to freeze damage or affect their ability to thrive in the spring.
When is it Safe to Clean-Up Perennials?
The best time to clean up perennials is after the first hard frost. A hard frost is when temperatures dip below -2°C for a prolonged period, causing most of the plant's above-ground parts to die back. In southwest Saskatchewan, this usually happens in October, though it can vary depending on the weather each year.
Here are a few guidelines to follow:
Wait for Frost: Wait until most perennials have been hit by a hard frost and their foliage has naturally started to die back. This ensures that the plants have had time to store enough energy for winter.
Look for Yellow or Brown Leaves: Once leaves turn yellow or brown and the stems begin to wilt or dry out, it’s safe to clean up. The plant is dormant by this point, and cutting back won’t affect its health.
Avoid Cutting Too Early: If you clean up before the frost or when the plant is still green, you might interfere with its natural processes. Leaving the plant standing until it fully dies back can also provide winter interest in your garden and some habitat for beneficial insects.
What to Cut Back and What to Leave Standing
Not all perennials need to be cut back in the fall. In fact, leaving some standing can provide added benefits to your garden and wildlife.
Cut Back Delicate Perennials: Some perennials, especially those with soft or herbaceous stems, can be cut back to the ground in the fall. Plants like peonies, daylilies, and hostas benefit from being cleaned up, as their dead foliage can harbor pests or diseases if left over winter.
Leave Woody-Stemmed Perennials: Some perennials, like Russian sage, sedum, and echinacea, have sturdier, woody stems that can be left standing until spring. These plants often provide winter interest and seeds for birds, while also offering some insulation from cold temperatures.
Mulch Instead of Cutting: For more tender perennials or plants that are borderline hardy in Zone 3, consider mulching rather than cutting them back. Leaving the foliage standing and adding a layer of mulch or straw around the base of the plant can help protect the crown (the area at the top of the roots, where next year’s plant will grow from) from fluctuating winter temperatures.
Fall Clean-up Tips for Perennials
When you’re ready to begin your fall garden clean-up, keep these tips in mind to ensure your perennials are prepared for winter:
Use Sharp Pruners: Clean cuts are better for plants, so make sure your pruners are sharp and sanitized. Cut stems down to about 2-3 inches from the ground.
Remove Diseased Foliage: If any plants showed signs of disease during the growing season, it’s important to remove and dispose of the dead foliage. Diseases can overwinter in plant debris, so don’t compost these materials.
Leave Beneficial Foliage: Leaving the dried stems and seed heads of plants like rudbeckia, echinacea, and grasses can create a winter habitat for beneficial insects and provide food for birds. Additionally, these plants add texture and interest to the garden during the snowy months.
Mulch for Winter Protection: Once you’ve cut back perennials, apply a 2-4 inch layer of mulch, leaves, or straw around the base of the plants. This will insulate the roots and help prevent the ground from freezing and thawing repeatedly, which can damage plants.
When to Delay Your Clean-up
In some cases, it may be beneficial to delay your perennial clean-up until spring:
For Pollinators: Some beneficial insects, like native bees, use the hollow stems of perennials for shelter over winter. By leaving certain plants standing, you can help support these pollinators, which are crucial for the health of your garden.
Aesthetic Appeal: Many perennials, such as sedums, ornamental grasses, and echinacea, provide visual interest in the garden even after they’ve died back. Their seed heads and structures can create a beautiful winter scene when covered with frost or snow.
Final Thoughts
Fall is a time to start winding down in the garden, but it’s also an important season for ensuring the health of your perennials for next year. In southwest Saskatchewan, wait until after a hard frost to start cleaning up your perennials, and don’t be afraid to leave some standing for winter interest and wildlife. By timing your clean-up correctly, you’ll give your perennials the best chance to thrive come spring.
By following these guidelines, you can confidently prepare your garden for winter and look forward to seeing your perennials bounce back stronger when the snow melts.
Happy Cleaning!
Ashton
