How to keep houseplants looking good in winter

December 30, 2018

The days are short, the sun is low, and the houseplants are sulking.

Meanwhile, I was carrying on as usual in their routine care--until the grape ivy on the indoor trellis announced its displeasure. Its leaves were drying up and dropping like crazy. New shoots were dying. The latticework, once all but invisible beneath lush foliage, was quickly becoming the focal point.

Had the infestation of mealybugs that had plagued the vine during the summer returned? No, a quick inspection found no sign of white cottony blobs, the signature of this insect pest.

Had I forgotten to water the grape ivy? No. Even though it looked like a lack of water could be the problem, the exact opposite was true.

When light is low, plants need less water. The roots of some kinds of plants, including grape ivy, are especially quick to rot if the soil is too wet. When I finally remembered to wait until the top inch of soil in the pot was dry before watering, my grape ivy began to regain its health.

Overwatering actually kills more houseplants than pests or diseases do, or--for that matter--underwatering.

Brown leaf tips are another frequent houseplant problem in winter. There are several possible causes. Dry air is a big one. Fluctuating soil moisture is another. Fluoride in the water or too much fertilizer can also be the culprits. Solving the problem may take some time, but destroying the evidence is quick. Just grab a pair of scissors and trim off brown parts.

Room temperature water is better for houseplants than cold water, which can be quite a shock to the roots of plants. Letting the water stand overnight not only warms it up but also allows chlorine to escape before you water.

If possible, avoid using softened water on plants. Filtered water, rain water, and distilled water are all better choices.

Excessive buildup of salts in the soil is harmful to plants. Use no more than the recommended amount of fertilizer and none at all during the dreary winter months, when plants aren’t growing. Once a month, clean the plant saucers. If the pots are moveable, take them to the sink or tub and let water run freely through the soil to flush out the salts.

To help keep fungal diseases from spreading, regularly remove any spotted or dropped leaves.

Winter is prime time for fungus gnats, which breed in potting soil that is too wet. Besides allowing the soil to dry out between waterings, you can also use yellow sticky traps to catch the adults. Shaking some granules of Mosquito Bits on top of the soil in your houseplant pots is one way to kill fungus gnat larvae. This product is non-toxic to humans and pets.

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