To mulch or not to mulch, to cover or not to cover, to bring in or let go -- these are the questions gardeners must ask themselves as winter looms. And like a lot of life's persistent questions, these have variable answers.
What kind of gardener are you? Are you the kind who considers every object in your garden an investment and every plant a friend, or do you treat garden items as affordable luxuries and plants as annual displays? The answer will determine how intensive your winter garden protection activities are.
We're lucky in the mid-Atlantic to have relatively mild winters well into December. I still see roses blooming, grasses with waving plumes, and even some impatiens and marigolds hanging on. Chrysanthemums are in their glory. So, it's easy not to consider what's going to happen over the next couple of months.
The annuals will go soon, often at the first touch of frost. Clear them out and, if they're healthy, add them to the compost heap.
What's left are perennials, grasses, trees and shrubs, most of which begin to go into necessary dormancy with cooler temperatures and shorter days. Do they need protection, and if so, how much? Also consider your water features.
If you're a laissez-faire gardener, or if you have already done the first, best thing to protect plants over winter, which is to use native species that are acclimated to local conditions, you can let your garden go and see what happens. If your perennials, trees and shrubs are established, they should make it just fine.
If you care about every plant, and if you use natives but conditions turn extreme, there are steps you can take to help plants survive. Generally, even under normal conditions, plants in Agriculture Department Hardiness Zones 3 to 7 can benefit from winter protection. We are in Zones 6 to 7.
Two conditions lead to winter damage: cold temperatures and dry, blustery winds. One night of frost will do less damage than an extended cold spell. Dry air and wind also wreak havoc over a long period of time. The best protection minimizes temperature fluctuations and protects against drying. The most common techniques to prevent damage are mulching, wrapping or covering, and moving.
Before you do anything, make sure all plants are healthy. If foliage is diseased or damaged, remove it, and put in the trash rather than the compost pile. If your roses have black spot or powdery mildew, wait until after the first frost, then remove all damaged foliage and dispose of it. Trim back perennials when their tops have died. Some people like to leave the stems to provide winter contrast or to create interest in snow, which is fine, as long as you trim them in spring before new growth begins.
If you have staked or espaliered plants, make sure their supports are strong and ties are secure. Nylon stockings make great ties.
Plants with good root systems survive best, and that means good preparation during summer. Dry soil, wind and cold temperatures cause desiccation of plants in winter, often called "winter kill." Keep watering non-frozen ground if there's little precipitation.
Mulch, made of chopped leaves, compost, weathered straw or bark chips, helps keep the soil cool in summer and warmer in winter. A layer of one to three inches is enough. Keep mulch low around the crowns of trees and shrubs, as it can encourage rot. Some people don't put mulch around the bases of plants because rodents like to burrow under it and gnaw.
You can protect plants from a sudden hard frost by covering them with a basket, bucket, cardboard box, plastic or even a bed sheet, but you have to remember to uncover them when danger is past. There are some commercial plant blankets that allow plants to breathe, and those can be left on longer. Wrap the trunks of trees with burlap, or build a burlap "fence" around a plant that might be in a vulnerable spot. Burlap fences also protect plants that could be vulnerable to wind. Branches and flowers of some trees and shrubs are particularly susceptible to wind and freeze damage. For example, crape myrtles can develop dead branches near the tops in the coldest of winters. Star magnolia buds will freeze and brown if there is a spring frost at critical flower bud formation time.
Newly planted or younger trees could also be susceptible to winter damage. Keeping trees pruned to a compact shape can help keep limbs from breaking. If heavy snow is toppling a plant, knock it off if it has just fallen. Snow provides moisture and some insulation, but too much can break branches. If you have plants near a road that is likely to get salt treatments in winter, wrap them or screen them with burlap or plastic to prevent salt damage.
If you have plants in containers, move them into a protected area, such as a patio or porch near the house, or into a garage or basement. If you don't have a place to put them and you have room and time, dig a hole and sink the containers in the ground.
Some people use an anti-desiccant, such as Wilt-Pruf, spraying plants thoroughly to keep them from drying out in winter. If you want to ensure complete protection with Wilt-Pruf, you will have to apply every six to eight weeks through winter. And, it must be applied when temperatures are well above freezing.
If you have a water feature in the garden, the best idea is to turn it off, drain, dry it out and store it somewhere. If you can't move it, you may want to drain and cover it.
If your water feature is a pond, consider the tropical plants annuals and let them go, or bring the plants inside. Place in an indoor pond, or a tub in a sunny location. Water lilies can be preserved by trimming to the top of the rhizomes and putting them in the bottom of the pond until spring. Or you can take water lilies out, wrap in newspapers and store in a garage or basement. They don't need to be submerged, but don't let them dry out.
If your outdoor pond is shallow, you might want to remove the plants and drain it. If the pond is less than 18 inches deep, you might want to bring the fish in to an aquarium. If the pond is deeper, fish usually make it through the winter with good aeration. Use a pump or gurgler in the top few inches, not deeper where the fish will be. Make holes in ice to let gases dissipate. Use the bottom of a hot teakettle or hot pan to make the holes. If you hit the ice with a hammer, you could stun or kill fish. There are also pond heaters that work at a low temperature and can remain plugged in all winter.
Even with all the protecting you do, you can still lose a plant or fish. Think of this as an opportunity for you to add something new to your garden.
Joel M. Lerner is president of Environmental Design in Capitol View Park, Md. E-mail or contact him through his Web site, www.gardenlerner.com.