Dear Master Gardener: I didn’t get all my plants mulched for winter and now they’re all buried under the deep snow. Will they survive?

Answer: Don’t worry. Snow is actually a really good insulator. All the air space between snowflakes gives snow an R-6 for 6 inches of snow. Flower buds which were set in the fall on shrubs such as azaleas benefit from the added protection and if you are taking a chance on Zone 4 or 5 plants here in Zone 3, a good snow cover may boost your odds of success.

Snow-covered plants are also shielded from sun scald and the desiccating winter winds. In addition, melting snow in the spring waters the plants just as new growth appears

Dear Master Gardener: The soil in my pots is turning white and crusty on top. Some of my clay pots have white around the rim. What is this?

Answer: It sounds like the soil in your pots has a build-up of soluble salts. These salts accumulate on top of the soil, forming a white crust. You may also see a ring of salt deposits around the top edge of your pots and on the outside of clay pots. You can prevent soluble salts from building up by proper watering. If at all possible, do not use softened water to water your plants because it adds chemical salts to the soil, which can build up and potentially injure the roots of your plants, just like fertilizer can. You can flush most of the salts out by holding your pot over a sink and watering your plant heavily, allowing the water to run out of the drainage holes. Discard any water left in the saucer so the salts you just leached out are not reabsorbed back into the soil through the drainage holes or walls of the clay pot. If there is a layer of salts on the top of your soil, remove it before you begin leaching. If the soluble salt level is very high you may want to repot the plant. When you repot a plant, choose a container with drainage holes so water can drain freely from the soil. Layering pebbles in the bottom of a solid container will not help soil drainage.

December Gardening Tips

  • Check on your produce, such as potatoes or winter squash, that you are storing. If anything has shriveled, developed soft spots, smells funny, or shows any signs of rotting -- get rid of it. If you have potatoes sprouting, it means they are not being kept cool enough. If they are turning green, they are exposed to too much light.

  • Poinsettias are easy holiday plants to grow, and contrary to popular belief are not poisonous. Make sure the plant is wrapped well when transporting it from the store to your car in cold weather. If it has a foil wrap, cut the bottom off or poke some holes in it so water will drain out of the pot and the plant isn’t standing in water. Poinsettias prefer a bright location away from drafts. Water thoroughly when the soil surface begins to dry, but don’t let the plant completely dry out.

  • Don’t hesitate to buy a fresh Minnesota-grown Christmas tree. They are a renewable crop grown on marginal agricultural land. Balsam fir is the most fragrant. Fraser fir is also fragrant and popular. Norway pine has stiff branches and needles that will hold heavy ornaments, whereas white pine has softer and longer needles.

  • Try to avoid using deicing chemicals on sidewalks and driveways, as it can damage nearby grass and shrubs. Damp sand, spread lightly will form a gritty nonslip surface and can be swept up in the spring.

  • Throughout the winter months, check your houseplants regularly for signs of insects or disease. Some signs of insect problems include fine webbing, discolored foliage, or shiny, sticky patches on leaves. Wipe insects and dust off of leaves (top and bottom) with a clean, damp cloth.

  • Do not fertilize houseplants at this time of year. Because of low light and poor growing conditions, plants need very few nutrients.

  • Let it snow! Snow insulates and protects plants through winter into spring.

University of Minnesota Extension Master Gardeners are trained and certified volunteers for the University of Minnesota Extension. All information given in this column is based on university research. To ask a question, call the Master Gardener Help Line at 218-454-GROW (4769) and leave a recorded message. A Master Gardener will return your call.