University of Vermont Extension 
Department of Plant and Soil Science

Winter News Article

STARTING HERBS AND OTHER DECEMBER GARDENING TIPS

Charlie Nardozzi, Senior Horticulturist
National Gardening Association, and
Dr. Leonard Perry, Extension Professor
University of Vermont
 

Caring for holiday plants, watching for spider mites on houseplants, and starting herbs are some of the garden tips for this month.

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. Cyclamen also prefer even moisture, so donít allow to wilt and definitely donít keep too wet or they may rot.

African violets make great houseplants and will flower in winter if given supplemental light. To propagate new plants, take a leaf cutting, dip the cut end in a rooting hormone powder, available at many garden centers, and stick the cutting in a pot filled with vermiculite or sand. Cover the pot with a perforated clear plastic bag and keep the soil moist. In a few weeks you'll have new plants.

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.

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 gardening tips for this month include shopping for gardening gifts for the holidays, making sure foil on pots of holiday plants has holes for drainage into saucers, visiting greenhouses to see new colors of poinsettias, and using plant-safe deicing products on walks and drives. Visit the National Gardening Associationís web site (www.garden.org) for more information on gardening and regional reports.


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