Winterizing Landscape Beds in Iowa
Iowa winters are hard on landscape beds. The freeze-thaw cycles heave plants out of the ground. The cold winds dry out evergreens until they turn brown. The weight of snow and ice crushes anything fragile that was left standing. But a little work in the fall makes a huge difference in how your plants come through winter. The time you spend winterizing your beds in October and November saves you from replacing dead plants and fixing winter damage in spring. It is an hour of work now that saves you a weekend of work later.
Start with clean-up after the first hard freeze. Once the frost has killed back the annuals and perennials have gone dormant, cut the dead perennial foliage down to 2 or 3 inches above the ground. Remove any diseased plant material and toss it in the trash, not the compost pile. Diseases can survive in compost and come back next season. Leave ornamental grasses standing through winter. They look beautiful when they are covered in frost and snow, they provide winter food and shelter for birds, and they add movement to an otherwise dormant landscape. Cut them back in early spring before the new growth starts.
Mulch is the most important winter protection you can give your beds. A fresh 2 to 3 inch layer applied after the ground has frozen insulates the soil and keeps the temperature stable. That stability prevents the freeze-thaw heaving that pushes perennials and small shrubs out of the ground. When the soil freezes and thaws repeatedly, expanding and contracting each time, plants get pushed upward and their roots get exposed to cold air. The mulch acts like a blanket that moderates those temperature swings. The key is to wait until the ground is frozen before applying the winter mulch. If you put it down too early while the soil is still warm, it can trap moisture and encourage rot.
Tender shrubs need extra help in the Cedar Valley. Broadleaf evergreens like rhododendron and boxwood lose moisture through their leaves all winter long. When the ground is frozen, their roots cannot replace that moisture, and the leaves dry out and turn brown. That is winter burn, and you see it everywhere in Iowa come spring. An anti-desiccant spray applied to the foliage in late fall coats the leaves with a waxy film that reduces moisture loss. For particularly exposed shrubs, a burlap wrap creates a windbreak that protects them from the drying winter winds. Do the wrapping on a mild day in November when the ground is still workable.
Do not forget about rodents. Voles and mice love to tunnel under mulch and through snow, chewing on the bark of young trees and shrubs at the base. A layer of mulch right up against the trunk creates a perfect highway for them. Keep the mulch pulled back 2 or 3 inches from the base of each plant. For young trees, a plastic tree guard or a cylinder of hardware cloth around the trunk protects the bark from chewing damage. In years with heavy snow, the rodents get access to higher parts of the trunk that are normally out of reach. A simple guard prevents a problem that can kill a young tree.
Watering is the step that most people forget. Evergreens and newly planted shrubs need moisture going into winter. If the fall has been dry, give everything a deep soaking before the ground freezes. That moisture in the soil acts as a reservoir that the roots can draw from through the winter. Plants that go into winter stressed from drought are much more likely to suffer winter damage. A thorough watering in late October or early November, depending on the weather, is cheap insurance. We always recommend it to our customers in Cedar Falls and the Cedar Valley.
We offer winterization services for landscape beds across the Cedar Valley. We do the clean-up, the pruning, the mulching, and the shrub protection in one visit so your beds are ready for whatever winter throws at them. If you would rather not spend your fall weekends hauling mulch and cutting back perennials, give us a call. We will take care of it and your plants will come through winter ready to grow.