Houseplants Suffer In Summer

Home & garden

June 6, 1986|By Joan Brookwell, Gardening Editor

When you begin complaining about the heat of summer, consider this: Your indoor plants don`t like it much, either.

During those pleasant months when we can leave our windows open a great deal of the time, houseplants become accustomed to plenty of fresh air and comfortable humidity. But comes the day when the temperature goes beyond bearable. Suddenly, the windows are slammed shut and the air conditioner goes on, lowering the humidity and slapping your poor plants with a blast of frigid air.

To make matters worse, you may turn off the air conditioner and close the windows when you leave for work or go off for the weekend. Your plants cook in a hot, muggy room.

There`s the matter of sunlight, too. The angle and strength of the sun changes from summer to winter, which can affect your indoor plants if the source of their light is a window or door. Not only are the days longer, meaning a plant will get more hours of light, but that light is also a great deal stronger.

Plants can sunburn. Leaves will get brown spots, and new leaves may be small and distorted -- curled under, for example. A combination of too much sun and heat may cause leaves to turn pale or yellow.

High temperatures may also cause weak growth and less resistance to insects and disease. On the other hand, put a plant right in front of an air- conditioning vent and it is almost sure to die.

Plants can adjust to different temperatures and light levels, but they`ll need your help.


In the summer, you may have to reposition them. Move them farther away from window or glass door, or set them at a north or east window. Don`t move them to a dark corner unless you provide supplemental artificial light.

Summer generally is a period of growth, and your plants will need more watering and fertilizing than during the slow-grow days of winter. Let common sense guide you here. Water when the soil feels dry, not because you`ve set up a schedule that calls for watering every three days. Plants with large, thin leaves will need watering more frequently than those with succulent stems and foliage. Water thoroughly so that it runs through the drain hole at the bottom of the container, but don`t let the pot sit in the drainage water longer than an hour or so.

Because air conditioning decreases humidity so drastically, ferns and other moisture-loving plants will benefit from misting. Mist the air above and around the plant instead of spraying the leaves directly. Plant containers may also be set in trays partially filled with pebbles, with water added to just below the surface of the pebbles. This will increase the humidity around the foliage.

Plants that go through the winter with virtually no plant food should have their nutrition stepped up. You may use a very weak soluble solution as often as once a week, although monthly feeding is enough for most indoor plants. In any case, keep the mixture on the weak side. You may prefer to apply slow- release fertilizer pellets that will continue to feed a plant for about three months.

New growth will attract insects, most of which will also thrive under hot, muggy conditions. If you inspect your indoor plants every few days, checking especially under leaves and in axils where insects can hide, you can catch any pests before they do major damage. For indoor plants that cannot be taken outdoors for spraying, washing with a mild detergent solution or insecticidal soap (follow label directions) will control most insects. If you see a mealybug or two, or a few aphids, dab them with a cotton swab dipped in alcohol.


What do you do about your plants if you take off for the Bahamas for a week? Besides the obvious plan of having a friend or neighbor care for them, you have several options.

-- Put them outdoors. Not in the bright sun, of course, but in light similar to what they were receiving indoors. That may mean placing them under a tree or some shrubbery, or in a shady, screened patio. Unless they are in a screened area, they`re likely to pick up a few bugs outside and should be inspected carefully before you return them to the house. (A word of caution: In placing indoor plants outdoors, they may receive too much water from summer rain storms, with the subsequent danger of root rot.)

-- If you have no yard or patio, plants may be kept healthy for a week or so by filling a sink or tub with few inches of water and setting the potted plants on upturned pots so their bottoms are above the water level. The humidity will provide enough moisture.

-- Cloth wicks -- strips of old nylons work well -- are another possibility. Wet the strip of fabric, tuck one end in the container (either in the top or through the drainage hole) and the other end in a reservoir of water.

-- You might also want to try a product called Wilt-Pruf, which, when sprayed on a plant, leaves a transparent coating that helps keep the foliage from losing moisture. This anti-transpirant is used by nurserymen when shipping plants, and is now available to the consumer in aerosol containers and quart- size spray bottles. It is also recommended for newly purchased plants to help them through the transition period while they adjust to a new environment.

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