Adding mulch too early in the spring will delay plant growth, as mulch will keep the soil cool. On the other side of our growing season, adding mulch too soon in the fall will keep the soil warm (and moist) for a longer period of time, which can increase the incidence of disease.
Winters can be very tough on plants—and on gardeners. It’s difficult to anticipate your plants’ needs during cycles of freezing and thawing conditions. Straw, hay, pine needles, bark or woodchips make great winter mulch and provide insulation for times of periodic warm spells. Late in the fall, after the first freeze, mulch should be applied 2-4 inches thick. Take care not to pile mulch too close to perennial plant stems or tree trunks. This can be harmful and attract pests, disease and excessive moisture.
If by chance you missed the window to mulch in the late fall or early winter, you may now be staring at bare ground and wondering what to do. The best plan of action is to check for bulbs or entire root systems that may have been heaved to the surface from greatly fluctuating temperatures. Allowing exposed bulbs or root systems to freeze and thaw will most likely result in the death of the plant. Take action by either re-burying the exposed plant parts or adding a nice thick blanket of mulch to protect the plant until the threat of frost is gone.
Once winter is over and the ground has had a chance to warm, it’s time for spring bark mulch or compost. The key throughout your growing season is to build micronutrients in the soil. I highly recommend focusing on at least 2 inches of well-rotted and aged compost when adding anything to your garden beds. If it’s weed suppression and looks you’re after, you can top dress with a light layer of wood chips or bark.
Calie Ramisch, Landscape Gardener and Volunteer Coordinator
Fort Williams Park Foundation calie.ramisch@fortwilliams.org