Rocky Mountain states checklist

What to do in your garden in December


Fresh holiday color-makers. If you're looking for alternatives to poinsettias, these indoor plants have colorful flowers or foliage: azaleas, bromeliads (Guzmania hybrids), Christmas cactus (Schlumbergera x buckleyi), kalanchoe, or Phalaenopsis orchids.

Living Christmas trees. Four hardy candidates are alpine fir, Colorado blue spruce, Engelmann spruce, and white fir. During its indoor stay, care for the tree as suggested at left. After the holidays, move the tree to a cool, bright porch where its rootball won't freeze. When the soil is workable, you can transplant it into the garden. Norfolk Island pine (Araucaria heterophylla) is a subtropical conifer you can keep indoors year-round.


Care for poinsettias. Select plants that are fully colored, with dense, green foliage all the way to the bottom of the stems. Before you leave the store, have the whole plant wrapped in a plastic or paper bag to protect it from cold air during transport to the house. Place in a room that's cool but not drafty, away from heat sources, and where it will get at least six hours of bright, indirect light. Water whenever the soil dries out, but don't let the soil get soggy or allow water to puddle in the saucer. Poinsettias don't need fertilizer during bloom.

Control whiteflies indoors. Plants brought indoors to overwinter may harbor whiteflies, which can quickly spread to other houseplants and reach damaging numbers. To control, spray infested plants every 5 to 7 days, applying neem oil for two treatments and summer oil for the third treatment. Be sure to spray the undersides of leaves to kill the eggs. Set out yellow sticky traps to catch flying adults. In greenhouses and sunrooms, release predatory Encarsia wasps, available from Planet Natural ( or 800/289-6656).

Identify garden microclimates. Walk through your garden to see where the snow lingers longest. Snow provides good insulation from extreme cold, making these places ideal microclimates for broad-leafed evergreens like boxwood and conifers such as arborvitae and yew. They're also suitable spots for perennials that need protection.

Prevent snow damage. To prevent a heavy snow load from damaging conifers, tie branches loosely with twine in the direction they bend easily, the same way growers bundle cut Christmas trees for delivery to sales lots. To protect daphne, holly, rhododendron, and other delicate shrubs, construct a "tent" over the plant either with snow fencing or two pieces of plywood or heavy lattice, attached with hinges at the top like a sandwich board. For small plants, wrap burlap around a frame of stakes pushed into the ground; leave the top open.

Study your winter landscape. Make note of areas in your yard where evergreens could make the winter landscape more interesting. Choose needle-leafed ones for sunny areas and broad-leafed kinds for shade. Also consider where ornamental grasses would make a strong statement. Mark future planting sites with a stake, then install the plants when they become available next spring.

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