By Leslie Mahin
Most of our houseplants are from tropical or desert areas where cold weather is rare, and they thrive in summer conditions outdoors. However, when night temperatures drop below 50 degrees, it is time to bring tropical plants indoors to avoid stress. Many gardeners slowly readjust their houseplants to indoor conditions by bringing them in at night and moving them back outside during the day similar to hardening them off in spring. A week of this routine helps plants prepare for the changes
in humidity, air circulation, and temperature. Some of us, however, have less time to devote to the gradual adjustment. In this case, pick a sunny day in early October to bring in all your plants at once. At this time of year, there is usually very little temperature difference between outdoors and indoors and your plants are more able to adjust to the change.
The first step to bringing in your houseplants is to clean them up by removing damaged leaves and spent flowers. Closely inspect every leaf and pot for spiders, ants, ladybugs, pill bugs, centipedes, and the like. Houseplants that are active in the wintertime, such as Christmas cactus, calla lily, pregnant onion, and dracaena, can be submerged in a large bucket. After a minute or so, unwanted pests will float to the top and can be skimmed off. Plants that are dormant or semidormant in winter should not be watered or soaked before the move indoors. These include aloe, agave, string-of-pearls, and most other succulent or bulbous plants. They are accustomed to a dry period of a few months. Clean the insects off by hand or with a dry cloth. Once you’ve taken care of the harmless insects, you need to inspect for plant damaging pests. Outdoors, spider mites, whiteflies, thrips, and aphids are usually kept in check by predators and environmental conditions. Indoors, these pests can rapidly get out of control. Wash the upper and lower surface of each leaf with insecticidal soap, or spray with a broad-spectrum indoor insecticide. Indoor Pharm, an organic houseplant insecticide, is a good safe choice. Monitor your plants through the winter and wash over the sink or spray with insecticide every couple of weeks to keep the pests in check. Place bright-light loving plants in south and west windowsills. You can group lower-light plants on stands or tables near windows. In winter, most houseplants need less water and fertilizer. However, if your house is particularly dry, plants that like humidity, such as African violets, orchids, benefit from sitting on a humidity tray. This is simply a shallow tray filled with garden stones and water. Be sure the pots are sitting on the stones up out of the water. As the water evaporates, it raises the humidity around the plants. Houseplants add color and vitality, not to mention oxygen to our homes. They work wonders in lifting the winter doldrums.
Bringing in Tender Bulbs
Some tender perennials, especially summer-blooming bulbs, require a dry, dormant period during winter. Lift elephant ears, begonias, and amaryllis before a hard frost and allow the bulbs (some are technically corms or tubers) to dry in a cool, shaded area. Clean debris and spent leaves from the bulbs, and place them in a box or bag in dry peat moss, mulch, or sand. Dahlias, gladiolas, and cannas can stay out until after a hard frost. Once the leaves and stems have turned black or mushy, trim any stems to a few inches above the bulbs, carefully lift the bulbs, and let them dry in a cool, shady spot. Once dry, place the bulbs in dry peat, mulch, or sand, and store them in a cool, dry, dark location where temperatures will remain above freezing – 40 to 45 degrees is the ideal temperature. Once a month, check the bulbs to make sure they are not diseased, wet, or shriveled. They should feel dry and firm, like a good sweet potato or onion. Discard any diseased or rotten bulbs.