In areas that experience freezing temperatures, winter mulching differs from mulching during the growing season. We mulch our gardens in the spring to suppress weeds, retain moisture and feed and warm the soil. While we may spread a layer of soil conditioning compost or manure in the fall, the primary reason for winter mulching is to protect our plants from the harsh conditions of winter freezes, thaws, and winds.
Why Mulch the Garden in Winter?
The main idea behind winter mulching is to keep the ground frozen by shielding it from the warmth of the sun. A steady temperature will keep plants healthy and prevent it from triggering new growth during a brief warm spell. Tender, new growth too soon will just result in more winter die back. Mulching now will also help conserve whatever water is in the soil, so hopefully, you’ve been keeping your garden beds watered right up until the hard frost.
What Can You Use to Mulch the Garden in Winter?
- Any loose, insulating material will do. Keep in mind that you’ll need to remove the mulch in the spring, or at least rake it aside. Choose a material that’s easy to handle such as straw, pine needles or shredded leaves which are all easy to remove or easy to work into the soil.
- If your ground doesn’t freeze until after Christmas, you can use the cut boughs of your Christmas tree as a mulch covering. These are nice because they’re so easy to remove in the spring.
- The easiest mulch is snow cover, but we live in Indiana and one day it will snow, and the other day will prove to be sixty degrees. If we do get a snowfall, know that it is a great insulator and protector of plants.
- Some plants will simply collapse onto themselves and act as self-mulches. Chrysanthemums survive best if allowed to do this.
When Should You Apply Winter Mulch?
- Protect Surface Roots: When it comes to newly planted plants, mulching is important. The best way to protect most perennial plants takes place when the soil has started to harden, which is generally after the first hard frost. A hard frost is usually defined as when temperatures drop to below 25 degrees F., but you’ll know it when you see the last of your strong annuals crumbled and brown in the morning. At this point, your perennials should be well into dormancy and mulching around them won’t encourage tender new growth. The ground has had time to chill and absorb fall moisture. At this point, The Cutting Edge can spread the mulch to protect your beloved plants, bushes, and flowers.
- Grafted plants benefit from being mulched more heavily. These are usually mulched with compost or soil and are actually buried to just over the graft union. You can pile the soil up around the stems or wire fencing filled with compost can be used.
- Woody plants: These plants are not as “needy” as some others, yet a 2 – 4″ layer of shredded bark mulch or compost does help conserve the ground moisture. We will be sure not to pile it around the base of the plants so it does not hinder its growth. We will keep it several inches from the stems or you’ll invite rodents, like moles and mice, who like the cover of mulch while munching on the bark. Mulching up against the stems also holds too much moisture against the plant, providing ideal conditions for diseases to take hold.
- Prevent Heaving: In Indiana winter, the ground repeatedly freezes and thaws, therefore it expands and contracts. When a plant is sitting in ground that expands and contracts, its roots get loosened from where they are anchored underground and the plant eventually gets pushed up through the surface of the soil, exposing its crown and roots to freezing temperatures and drying winds, which brings us right back to Reason to Winter Mulch #1. Again, you would wait until the top of the plant has died back and the ground has frozen, before applying a layer of mulch.
- Prevent Erosion: Mulching unplanted garden beds can be done at any time in the fall. Ideally, you would plant a winter cover crop and let it sit until you till it under in the spring. If you choose not to plant a cover crop, it would still be beneficial to have us spread a layer of compost, manure or shredded leaves in and around the garden. Also, fences are used to contain the shredded leaves, which works well. The shredded leaves mulch the vegetable garden all winter and in the spring, that mulch can be spread to the flower beds.
As we wait for spring to approach, we should wait until the hard frosts have finished falling completely. This is Indiana, though, so sometimes that is beyond our knowledge. We can remove winter mulch in the spring months when all danger of a hard frost is past, and leaving the winter mulch in its place until then can be beneficial. When the ground starts to thaw and the smell of mud is in the air (does anyone like this smell?), it’s time to start raking and removing the mulch so that the ground can warm and new growth won’t be inhibited.