There’s a common practice among some landscapers that suggest putting a thick layer of mulch over your beds this time of the year. We’re not going to argue that practice if that’s the way it has always been done. What we might suggest is that instead of adding the mulch on a warm Saturday afternoon, you wait till the temperatures drop and remain low for an extended period of time.
There is a big difference between spring-time mulching and late fall mulching for winter protection. Spring mulching is done for appearance, reducing weed seeds from germinating, conserving moisture and moderating soil temperatures.
Winter mulch’s primary function is to moderate soil temperatures. There are times throughout the winter months when temperatures getting really cold, then get really warm and then get really cold again. It is this freeze and thawing that damages our plants. While air temperatures can fluctuate greatly, it is the soil temperature that starts things moving. A warm soil tells the plants its time to start growing and begins sending nutrients to the plant’s vascular system. When below freezing temperatures return, those nutrients freeze and burst killing that section of the plant.
It is best to wait until after colder temperatures arrive and stay before applying protective mulch around your plants. Waiting allows the ground to cool off, a signal for the plant that winter is coming and it’s time to go dormant. Putting the mulch on too soon, may encourage the plant to persevere growing.
A couple of important steps should be taken with roses. First, pull back any existing mulch already around the roses. This old mulch can harbor insects and diseases. Then apply a fresh layer of mulch (ideal mulch is chopped leaves) around the base and up into the stems. Then later add protective screen around the rose bushes and add more leaves. For trees and shrubs, a 6″ protective layer is good. For perennials, just a 2″ layer works find.