Gardeners in cold climates never know what to expect during the winter. There might be snow, unusually warm conditions, too much precipitation, or not enough. Chances are good that a mixed bag of weather will greet outdoor plants. Even if you strictly adhere to buying only plants that are hardy in your zone, there's no guarantee nature will stick to the agreement. So it helps to have some tricks in your bag to protect your special plants and those that are marginally hardy in your area.
Bring Outdoor Plants Indoors
Some garden plants are perfectly happy to be brought indoors and grown as houseplants. They can handle the drier winter conditions and most even enjoy the cooler temperatures. You might have to test out the best spot for sun exposure because winter sunlight isn't very intense. But bringing in coleus or fuchsia is a nice reminder of the garden that was and the one that will be.
Overwinter Plants in Containers
One of the biggest headaches is how to overwinter plants in containers. Plants that are at least two zones hardier than your growing zone should be able to survive the winter outdoors in containers. You might need to provide some extra insulation and be certain your container is made from a frost-tolerant material.
Take Cuttings to Propagate More Plants
If space is an issue for over-wintering plants but you still want to retain some for next year, consider taking some cuttings of your existing plants. They will start out small and grow slowly. But if you have a favorite begonia, plectranthus, or coleus and you want to make sure to have it in your garden next season, cuttings are an easy, inexpensive way to create more plants.
Winter Rose Care
Roses always seem to come through winter with a little damage. Sometimes they refuse to go dormant and are hard hit by frost. Or perhaps black spot or chafer beetles stick around for the winter to get an early start in the spring. Many roses are grafted onto rootstock and need a little extra protection to prevent the graft from winter injury. Prepare roses for winter by coaxing them into dormancy and employing selective pruning, among other methods, to help your roses batten down for winter and survive intact until spring.
Store Tender Bulbs
Summer blooming bulbs require so little care during the growing season that they are hard to resist. Who doesn't love a little touch of the tropics in their garden? Unfortunately, when you don't actually live in the tropics, you can't leave the bulbs in the ground over winter and expect them to survive. If you want to grow your cannas, dahlias, and elephant ears again next season, dig them up after the first frost and store them indoors for the winter.
Overwinter Hardy Mums
Chrysanthemums, also known as garden mums, are usually labeled as being hardy, but more are tossed into the compost pile than make it through winter. The mums that appear for sale in garden centers in the fall have been treated and forced to look picture perfect in your fall gardens. They can survive the winter, but they'll need a little TLC. Many other types of mums can grow in your garden that are truly hardy and indifferent to winter. You might want to try both.
Gardeners love to overwinter geraniums, and in USDA hardiness zones colder than Zone 10 there are several options to overwinter geraniums, such as saving cuttings, until they are ready to go back outdoors in the spring. If your home has enough sunlight, you can grow them as houseplants on a sunny windowsill.
Winter Care of Waterlilies
What's a water garden without water lilies? Some water lilies are hardy down to USDA hardiness Zone 3. They can be left in the water provided there is enough depth for them not to freeze. Tropical water lilies and hardy water lilies in shallow water must be overwintered indoors. Doing so can be a little messy, but you'll be ahead of the game if you want to divide them in the spring.
It might sound like wasted effort to mulch a garden in winter, but winter mulching is a different type of mulching. Rather than suppressing weeds and conserving water, winter mulching keeps the ground frozen. The frozen ground won't kill hardy plants, but repeated freezing and thawing cycles will. The expanding and contracting of the soil can push plants out of the ground.
A layer of snow is excellent winter mulch for plants because it provides a layer of insulation. If snowfall is sparse and doesn't provide that protection, winter mulching is the next best option.
A Visual Guide: Rose Problems. Missouri Botanical Garden.
Mulch to Prevent Winter Injury. Department of Plant and Soil Science, University of Vermont.