Most plants grown as houseplants originated in the tropics, so nighttime temperatures dipping into the 40's and 50's deg. Fahrenheit mean it's time to bring them inside.
These plants won't survive frost and some may be damaged by temperatures in the 40's or even the low 50's. As summer winds down into fall, days may be warm enough but nights too cold for them to stay outdoors.
It's wise to examine plants closely when you bring them inside and keep them separate from other indoor plants for several weeks. Like outdoor plants, houseplants growing outdoors can become infested with insects, spiders and other pests or develop diseases. In the warm indoor environment, insects that hitchhike indoors on plants may thrive and multiply. Keeping plants that spent the summer outdoors separate for several weeks makes it easier to keep an eye on them, treat any problems that develop and keep them from spreading to other plants.
For minor infestations, try washing plants carefully with water or a mild soap solution. Houseplant insecticides are available at your garden center for more serious infestations. Rather than risk spreading the problem, you might choose simply to discard severely infested plants and replace them.
Plant diseases may be more difficult to treat than insects. Like insects, they can spread from plant to plant so discarding diseased plants may be the best choice. Repotting may eliminate pests such as thrips or ants that took up residence in potting soil.
Plants that outgrew their pots over the summer will also need repotting. To check for crowded roots, hold the top of the plant with one hand and the pot with the other and rap the edge of the pot on a hard surface to loosen the root ball. If it consists of a mass of roots with very little soil showing, it needs repotting into a larger container.
If the root ball looks fine but the pot is top heavy from top growth, pruning may be in order. Broken or otherwise damaged plant parts should also be removed.
A common occurrence after plants come back indoors is leaf drop as they adjust to significantly lower light levels. Putting plants where they'll receive all the natural light possible and/or supplementing natural light with light from fluorescent tubes should reduce or prevent leaf loss.
Remember that plants growing indoors aren't subject to the drying winds and warm temperatures that they experienced outdoors, and growth will slow down with the reduced light. The summer practice of frequent watering needs to be adjusted to avoid overwatering.
Water when the soil is beginning to dry out rather than on a regular schedule. And stop fertilizing altogether. Fertilizing when plants aren't actively growing results in a buildup of fertilizer salts in the soil that can damage plant roots.
When you check the soil for moisture, use the opportunity to examine plants for developing insect or disease problems. Indoors, a minor problem can become a major one seemingly overnight.
(This resource was added September 2003 and appeared in the Lincoln Journal Star Newspaper Sunday edition. For information on reproducing this article or using any photographs or graphics, read the Terms of Use statement)
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