From The Ground Up: Keep annuals alive throughout winter months
As the sun sets further to the south and evenings become shorter, we sadly realize that the growing season is winding down. But you don’t have to say goodbye to your favorite annuals just yet. If you have a sunny spot or a grow light, you can keep a little bit of summer through the cold days of winter.
Before the first freeze, dig up your annuals or bring in your potted plants. In order to avoid bringing in any insect buddies, place your potted plants in a plastic garbage bag and spray with Sevin or an insecticidal soap. A day or two in the sealed bag will stop bugs from becoming your new roommates. Place plants in a sunny location without a draft for the winter. Prune as needed to keep plants full and not leggy.
So go ahead and save that lovely Mandevilla, even though it will lose many leaves, it will come back for a summer of blooms. Geraniums will even flower in the winter months given enough sun and water. Coleus will brighten up winter days given sun and regular water. Gerbera Daisies can be dug up, carefully preserving the tap root, and can be kept alive all winter in a sunny spot indoors.
Some plants won’t thrive indoors like they do outdoors. Fuchsia and impatiens will survive the winter but the goal with these plants is not to have them flower but to ease the plant into dormancy. Place them in the basement or attached garage and water every three weeks or so. The plant’s leaves will fall off and it will appear dead, but about a month before the last spring frost, place the plants in filtered sunlight. Water weekly after cutting back its foliage that remains by about half. Once it starts growing back and temperatures warm slowly acclimate it back to outdoors.
Problems with overwintering tend to be low humidity and possible pests. Keep your humidity levels up with a room humidifier, trays of pebbles with water under the plants, or massing potted plants to significantly raise the humidity level. Check your plants regularly for powdery mildew, spider mites, scale, and other pests. Keep alcohol and cotton balls handy to topically treat infected plants. A neem oil spray may also be needed to treat pests.
If your space is limited, you can save summer by taking cuttings from your favorite annuals and rooting them. Take a 3-inch healthy leafy cutting from geraniums, coleus, begonias, sweet potato vines, new guinea impatiens, and petunias, dip into a rooting hormone and plant firmly in small pots with potting soil. They will grow slowly during winter in a sunny windowsill of your home. Water them frequently and keep them from drafts.
So save a little summer in your home this winter and get a head start on spring.
l For gardening questions, call the Linn County Extension Master Gardener Hortline at (319) 447-0647.