Summer vacation over for most houseplants

Bringing houseplants back indoors is an admission that the gardening season is ending. Still, it's a job better done now than on the first nippy night because there'll be plenty of other things to do when that frosty evening threatens. Tomatoes and peppers will need covering or gathering, and you might want to fill vases with the summer's last flowers.

Houseplants can be moved indoors now at a relaxed pace. The best reason to bring houseplants indoors now rather than in a few weeks is because the plants will suffer less shock in the transition. Windows still are open and furnaces remain cool and quiet, so the air indoors is about the same as it is outdoors. Not so in a few weeks. A sudden change from cool, moist air outdoors to warm, dry air indoors shocks houseplants, causing some leaves to yellow, then drop.

Not all of your houseplants are necessarily worth keeping through the winter. In the calm of the present moment, decide which plants go to windowsills and which go to the compost pile.

Clean leaves on plants

Also try to leave all insects and disease pests outdoors. Pests find it too easy to hopscotch among plants clustered together on windowsills. And natural predators are unlikely to be indoors to keep pests in check.

Begin cleaning up each plant by trimming off any diseased leaves or stems. Then check each plant carefully for insects. Look among the leaves and branches, especially for scale insects and for white tufts of mealybugs.

If a pesticide is needed, spray it while the plant is still outside. You will be exposed to less of the spray than in the confines of a room, and you do not have to worry about getting the spray on furniture or windows. At the very least, give each plant a thorough hosing with plain water.

Just a few houseplants do best if left outdoors as long as possible. Generally, these are winter flowering plants, such as Thanksgiving, Christmas, and Easter cacti, and poinsettia, jasmine, and amaryllis.

A slight drying of the soil and a few chilly -- but not freezing -- nights help bring on the flowers of these plants. Long nights of uninterrupted darkness also help bring on the flowers of poinsettia and the cacti.