Released: January 23, 2004

Indoor Gardeners Must Stifle Wintertime Nurturing Urges

MANHATTAN, Kan. – If houseplants are looking sickly and perhaps shedding leaves, they do NOT need extra fertilizer or water. Winter is when Northern Hemisphere gardeners must be “cruel” to be kind.

“Low light levels are the usual cause for unthrifty plants at this time of year. The light deficit creates stress, which houseplants respond to by slowing down or stopping growth. They also may do some leaf thinning throughout the plant. Your adding more nutrients or moisture to this process could be really harmful,” said Ward Upham, Master Gardener program coordinator for Kansas State University Research and Extension.

For best plant health, everything must be in balance – food, water and sunlight, Upham said.

“When low light levels create a plant slowdown, any extra nutrients you provide will just stay in the soil. But, those nutrients can build up and eventually may burn roots,” he said. “Excess water can drown roots.

“In either case, your plants will look far worse and might even die.”

The best thing plant owners can do now, Upham said, is to add supplemental (artificial) lighting or to be patient until spring allows houseplants to recover.

If indoor gardeners haven’t already made the seasonal shift, they also should reduce or eliminate fertilizing through winter. They should irrigate only when the top one-half inch of pot soil becomes dry.

They can gradually return to providing “normal” care levels when spring brings more light and renewed plant growth – indoors and out.

“If a houseplant still looks thin several weeks into spring, you might want to cut it back, too, so it can put out new, thicker growth,” the horticulturist said. “Also, knock the plant out of its pot to check whether it’s root-bound. If so, move it into a somewhat larger container.”

Winter’s shorter days aren’t the only reason for the season’s decrease in light, Upham said. The sun actually is closer to Earth’s northern latitudes in winter than in summer. Even so, the quality of light it produces is less useful for plants. The sun’s winter orbit is closer to the horizon, and this limits the spectrums of light that get through.

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K-State Research and Extension is a short name for the Kansas State University Agricultural Experiment Station and Cooperative Extension Service, a program designed to generate and distribute useful knowledge for the well-being of Kansans. Supported by county, state, federal and private funds, the program has county Extension offices, experiment fields, area Extension offices and regional research centers statewide. Its headquarters is on the K-State campus, Manhattan.

Story by:
Kathleen Ward, Communications Specialist
kward@oznet.ksu.edu
K-State Research& Extension News