A year ago we experienced nearly unprecedented winterkill of perennial flowers. Often several intertwined weather and environmental conditions contribute to the problem. But one of the major causes of winter die-out is occurring right now, in late winter. The months of February and March are very dangerous times to be a perennial flower.
Warm spells alternate with cold spells. Snow, which is nature’s great insulator, disappears, leaving perennial flowers and strawberries uncovered and unprotected. Soil thaws and then refreezes. Cycles of freezing and thawing tear the roots of perennials and can often “heave” them upward. Roots are damaged and plants are exposed to drying winds, alternately warm and cold.
After the snow disappears, if perennials were not mulch-covered last fall for winter protection, they can easily be killed. The reason for covering perennials with mulch in the fall after the ground is frozen, is to keep the soil consistently frozen. Our hardy perennials can take the cold, but they cannot take the thawing/freezing, exposure and drying winds that unprotected, non-snowy conditions cause. Since snow is undependable, 12 to 24 inches of leaves, straw, chips or compost helps keep the soil uniformly frozen until spring weather stablilizes.
What do we do this time of year, if the snow has disappeared and we didn’t put protective mulch on our perennials last fall? Much of the damage occurs now, so it’s wise to cover them as quickly as possible. Any amount will help, but try for a layer at least 12 inches thick, or greater.
What materials can be used now to provide insulation for perennials?
- Straw is available from some garden centers who might still have some on hand.
- Peatmoss is available in bales from garden centers. It’s very dry, so it needs to be thoroughly moistened before using, or it will blow away when applied over the perennials. When spring arrives, the peat can be spread out over the perennial bed and worked into the soil.
- Woodchips or woodmulch.
- You might still have some leaves in the corner of the yard that could be used as perennial cover.
When the spring weather stabilizes without the wide swings from warm to cold, the protective mulch can be removed. It can be loosened in stages. Check perennials as spring approaches and remove the mulch as new growth is starting. As new shoots begin to emerge, the mulch can be raked aside a little, and then removed completely later.
Keep your fingers crossed. We don’t want our perennials freezing to death (or thawing to death) this year!