It’s been an unusually mild winter. The lack of cold weather has been replaced by an abundance of rainfall and dearth of sunshine. Most people I’ve come across over the past few weeks have opened their conversation with some variation of “I wish we’d get some sunshine.”
Plants, like people, suffer the “blues” when the daylight grows dim and short—especially indoor plants. The normal progress of shortening day length that starts in mid summer signals plants to take a rest. They stop growing as fast, usually don’t bloom as freely, and subsequently require fewer nutrients and less water. The plants are resting and so should your watering arm. Plant disease and death by drowning are a major concern in the winter months. Ironically, one sign of overwatering is wilting, leading the unsuspecting plantskeeper to break out the watering can. Other overwatering symptoms include leaves that turn sickly gray-green or yellowish and fall off. Water only when the surface of the soil feels dry. For cactus and other drought tolerant species, hold off watering until the soil a bit below the surface feels dry to the touch.
Resist the urge to apply fertilizer in the off season, too. Semi-dormant plants don’t take up and process nutrients in as large quantities as they do when the growing season is at hand. Excessive fertilizer can lead to problems with pests such aphids. Salt accumulation also damages and kills roots. Normally the salt residues from fertilizer are flushed away with regular watering--but you shouldn’t be watering so much in the winter, right?
Low light levels contribute to a problem called etiolation, the scientific term for stretching. The plants become tall and wispy. They may also turn or lean toward the light more than usual. Unless you can provide them with more light, there’s little you can do about these problems. Move them as close to the window as possible without touching the glass or set up a fluorescent light stand just a few inches directly above the uppermost leaves. Let the lights run for about 12 hours during the day. For plants that lean toward the light, just give the pot a turn to get them to lean the other way for a bit!
Scale or mite infestations are another hitch in growing houseplants this time of year. Common brown scale is a small insect that appears as slightly raised waxy light brown bumps on the leaves. People usually first notice a coating of sticky, shiny honeydew the insects secrete on furnishings and plants. Systemic insecticidal plant spikes or granules clean up scale infestations very nicely. Another even smaller pest is the spider mite. This insect relative spins super fine silken webs under leaf surfaces and from leaf to leaf. Their feeding causes leaves to turn dull and off color. The lower surface of leaves may also appear “gritty” form the accumulation of fecal matter, cast skins and accumulated webbing. You can use a systemic insecticide or frequently bathe the plant’s leaves in tepid water every few days to wash the mites away.
For more information of home lawns, gardens and pests, contact The Garden Line at garden-line@udel.edu or 302-831-8862.
—Jo Mercer, Extension Educator, Horticulture & Environmental Science
Originally published in “Newark Outlook,” The Newark Post
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