Editor's note: This column will "move indoors" as the weather cools and will focus on home-related issues.
Many gardeners will not call it quits until the first frost forces them inside. Given some of the overnight temperatures of the last few weeks, we cannot deny it any longer. So we might as well admit it our outdoor gardening season is over. Now is the time to turn our attention indoors.
Luckily, we can ease our green thumbs from experiencing withdrawal symptoms by caring for our houseplants.
By now, any houseplants that were moved outside during the summer have been brought back indoors. They should have been inspected thoroughly and sprayed with a soapy solution to deter insects from being brought inside. The plants are well along in their process of being acclimatized to lower light conditions in our homes.
Acclimatization is the process by which the plant actually changes the structure of its leaves. In low light conditions, chlorophyll the substance used to convert sunlight to energy becomes more abundant and closer to the surface to better use the precious, sparse sunlight.
This change in the anatomical structure of the plant leaf can take eight weeks or more. To aid the process of acclimatization, reduce the frequency of fertilization for three months and ease up on watering, allowing the soil to dry between watering. Leaf drop may occur when acclimatization occurs too rapidly.
Create a comfortable climate
Besides light, temperature and humidity also affect the health and growth of houseplants. Fortunately, plants enjoy the same temperatures that people find comfortable between 65 degrees and 75 degrees during the day and 55 degrees to 60 degrees at night.
Keep houseplants away from entrances where blasts of cold air may damage them. For the same reason, plants should be far enough away from windows so their foliage does not touch cold glass panes.
Plants are frequently placed near windows, though, because that is often the brightest place. If so, pull the drapes or close the blinds at night to help insulate houseplants against too much cooling after sundown.
Conversely, avoid placing houseplants too close to sources of heat, such as hot air registers, radiators, televisions or other appliances.
We know all too well how dry the indoor winter air can be with the furnace or fireplace providing warmth but no moisture. Plants prefer a higher humidity than is typically present in the home during winter.
While our homes and offices often have only 10 percent to 20 percent of moisture in the air, plants prefer 35 percent to 45 percent humidity. Humidity can be raised in several ways:
l Place shallow trays of water near plants.
l Put pebbles in plants' drip trays and fill the trays with water.
l Group plants so they create a more humid microclimate.
l Place plants in bathrooms or kitchens where moisture is more common.
l Use a humidifier or vaporizer.
l Attach a humidifier to the furnace.
Water: when and how much
Houseplants need less watering during the winter because they are not growing as rapidly as they do during periods of higher light. Some pointers on winter houseplant watering are:
l Water when the soil is dry 1 inch below the soil surface.
l Use room-temperature water.
l Water less if leaf tips are brown and soft; water more if leaf tips are brown and brittle.
l Use clay pots if you tend to water too much; use plastic pots if you tend to water too little.
Plants require much less fertilization during the winter, and the strength should only be half of what's used during periods of vigorous growth.
Fertilizing houseplants three or four times during the winter is sufficient. A handy way to remember when to fertilize is to do it near the holidays Halloween, Christmas, Valentine's Day and April Fools' Day.
After April, when sunlight is stronger and longer, plants resume more rapid growth. Then, a more frequent fertilization schedule should be followed.
While not quite the same as the great outdoor gardens, houseplants are a wonderful way to keep our thumbs green during the winter months.
Carol Boncella is education coordinator at Lawrence Memorial Hospital and garden writer for the Journal-World.