Here, I answer a few of our readers’ winter gardening questions. I wish all readers a happy holiday season and successful gardening in 2026!
What winter annuals are deer-resistant?
It’s becoming harder to find cool season annuals that deer won’t eat, or at least leave alone most of the time. Obviously, flowers that are edible to us — like pansy, nasturtium and calendula — also are devoured by deer. Ornamental cabbage and kale taste the same, at least to deer, as the vegetable forms. This fall deer even pulled up or ate alyssum, a plant that used to be safe.
Cyclamen makes a brightly colored winter annual when planted in full shade and protected from deer.
Anthony Keinath
What’s left? Although dusty millers and foxgloves are not touched, they do not bloom during the winter. Wallflower, diascia, nemesia, cyclamen, stock and snapdragon are usually less attractive to deer, but plants should be sprayed with deer repellent after they are transplanted to discourage nibbling. I have not been able to find wallflower locally for the past couple of years. Stock does not do well in wet soil, so I put it in a pot this year.
How do you keep poinsettias alive?
A reader sent me a timely question: “Please tell me about poinsettias. How often should I water one? I have killed ones in the past and would like to preserve this one.”
Most poinsettias are killed by overwatering. Be sure the drainage holes in the pot are not blocked by the decorative foil around the pot. I suggest completely removing the foil or poking holes in it.
In general, water the plant when the soil’s surface is dry to the touch, about once or twice a week, depending on how dry the air is in the house. Check the plant twice a week. If a poinsettia gets too dry, the leaves will wilt dramatically; most of them will recover after watering, but the lower leaves tend to fall off if the plant is stressed for any reason. Poinsettias like bright but indirect sunshine, such as a south-facing window but placed far enough way that the plant is not in direct sunlight.
What should you use for frost protection?
Due to nighttime temperatures in the low 20s last week, it’s time for a refresher on protecting plants from freezing temperatures and frost. Plastic coverings provide no cold protection, because plastic does not trap the warmer air near the soil like fabrics do.
Weather apps on smartphones usually include the predicted dew point temperature along with the relative humidity. If the temperature reaches 32 degrees Fahrenheit or lower and the dew point is lower than the air temperature, then obvious white frost, called hoar frost in bygone years and stories, will form on surfaces, including plants.
A pot of winter annuals with alyssum, stock and chives (half-hidden).
Anthony Keinath
If the dew point is higher than 32 degrees Fahrenheit, dew will form on plants, which is common when air and soil are moist after rain. If the temperature drops below freezing, the dew freezes into a thin, clear coating of ice.
Both hoar frost and frozen dew cause more plant damage than cold, dry air does. Even cold-tolerant annuals like foxglove and snapdragon need protection from temperatures near 20 degrees Fahrenheit.
Lightweight fabric — such as a fleece blanket, bed sheets or old mattress pads — is an ideal insulator for plants, because it won’t break the leaves. Bath towels also work over sturdier plants. Be sure the fabric edges touch the ground to prevent cold air from moving under the cover. In windy conditions, weigh the edges with bricks, stones, pieces of lumber or 1-inch-diameter branches.
Fabric coverings also prevent frost formation directly on plants. Even if the fabric becomes damp and gets a bit icy on the outside, it will still prevent frost on the plants underneath it.
If a low-watt incandescent bulb or a string of incandescent Christmas lights is used as a heat source around larger plants, like citrus trees, then plastic is the preferred covering.
Pine straw, dried leaves and even Spanish moss can be used as extra protection around the bases of tender perennials like salvias, princess flower and lantana. The mulch protects the crown of the plant that will resprout next spring. This material should be removed, though, before a long, wet period, like a day of rain, to prevent crown rot.
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