The common myth is that we mulch our plants in the fall to keep the ground warm. The truth is we mulch in late fall to keep the ground cold. More winter hardy plants are killed by the freezing and thawing of our Nebraska winters than from the cold. So we want to put the mulch on the soil after a couple hard freezes and then keep the soil cold. I usually do not cover my roses until after Halloween and sometimes as late as Thanksgiving.

          Remember that warm spell we had in late January and early February of 2006. Plants that were not mulched warmed up and some broke dormancy. Then when we got the cold spell they could not go back into dormancy and froze. Also, gardeners who put their mulch on too early do not allow the ground to cool down normally and thus the plant does not go into dormancy as it should. In the early fall, you can keep the ground too warm and then when we get a sudden freeze, the plant is not ready and winter kills. In northern climates such as North Dakota and Minnesota where it snows and then stays all winter, some plants do better because the snow insulates the ground and keeps the soil from thawing out until spring. 

          What is the best mulch? Each gardener has his or her favorite. Gladys uses lots of compost from her huge compost pile. I use wood chips or shredded hard wood on my roses, shrubs, and other perennials because I have access to it. I use compost on my peonies, asparagus, and rhubarb. Some gardeners use shredded leaves and grass. Do not use leaves that have not been shredded by a grinder or your mower, or grass that has not dried out for a couple days. These tend to mat down rather than have air spaces which helps insulate.

          Do not use those foam cones unless you cut the top out and fill it with mulch, compost, or soil. On a warm winter day the heat builds up inside a cone with the top still on. This can heat up the soil and cause the plant to break dormancy. With the next hard freeze the plant freezes and dies. They are easy and convenient but they do not work.

          Remember, mulch in the winter to keep the ground cold, and mulch in the summer to keep the ground from drying out.

Copyright 2006 October 7, 2006