University of Vermont Extension 
Department of Plant and Soil Science

Winter News Article

Charlie Nardozzi, Senior Horticulturist
National Gardening Association, and
Dr. Leonard Perry, Extension Professor
University of Vermont
Sowing perennial seeds, cutting back indoor geraniums, and watching for spider mites are some of the gardening tips for this month.

If you have any clay or ceramic pots that you keep outside or in a cold location during the winter, empty them of soil which will freeze and expand and, most likely, crack the pot. Keep the soil to use to fill the bottoms of large planters next year. That way you won't need as much fresh soil.

Sow seeds of perennials that need cold treatment, such as alliums, gentians, monkshood, primulas, and alpine plants. Sow in flats and move them outside to a shady location, or sow directly in an empty bed outside. Cover with pine boughs.

Decrease water and fertilizer on Christmas cactus if the buds are developing. To prolong the colorful bracts on poinsettias, keep them where temperatures don't exceed 70 degrees F during the day or drop below 65 degrees at night. Keep potted amaryllis in a cool (60 degrees)
shaded location until buds open. Then move it wherever you like. Cyclamen prefer cool temperatures, so keep them back from south-facing windows that heat up during the day.

If you brought in your geranium plants this fall and are growing them indoors this winter, chances are they've become very leggy by now. The cloudy, short days of November and December don't provide enough light for these plants to thrive. Cut back the plants to about one foot tall. They will resprout and grow bushier in the longer days of late winter.

The warm, dry indoor air is prime breeding ground for spider mites on your houseplants. Look very closely at the undersides of leaves, at the base of stems, and on new buds for fine webbing. Set any suspicious-looking plants in the shower to wash off the mites, and repeat frequently. Or, if it's a small plant, you can swish it around upside-down in a sinkful of soapy water. Insecticidal soap also works, but it's smelly to use indoors.

If Mother Nature hasn't blessed you with snow cover on your lawn, don't walk on the frozen grass because you'll break grass blades and may cause dieback in your lawn that will show up next spring. Put up flagging or stakes in sensitive areas to keep visitors on the path.

The outdoor gardening season may be over, but indoors you can grow many herbs. Sow seeds of parsley, oregano, sage, chives, and dwarf basil in clay pots. Once they germinate, place them under grow lights and water and fertilize (with a half-strength solution) only when very dry. You'll be rewarded with fresh herbs for your winter cooking.

Other ideas for this month include gently brushing snow from shrubs, shopping at your local garden store for holiday gardening gifts, checking holiday indoor trees daily for water needs to keep them long-lasting and safe, and making holiday decorations from natural materials.     

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