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Over the Garden Fence

Get a gardening fix this winter with houseplant care

As we approach mid-January, there may be more going on inside than outside for gardeners. Perennial beds covered in snow enjoy the protection from drying winter winds and the winter sun (if we ever see sunny days anytime soon). For some of us, traditional bird feeding started weeks back. Maybe your Christmas tree got repurposed and put out for bird shelter, or your outdoor adventures mean keeping the feeding stations full of bird seed and suet, cobs of corn for the squirrels, and maybe a salt lick for other kinds of wildlife.

Inside the home is a bit different. Depending on your level of outdoor vegetable and flower gardening, there are catalogs to go over and lists to be made of seeds to be ordered. Gardening indoors this time of year also includes keeping your houseplants healthy.

In the darker days of winter, watering practices change as those plants are just maintaining and not really growing with the lack of good sunlight. It is very easy to overwater and cause root rots. If accidentally overwatered, clay pots are more forgiving and dry out quicker because they are porous. Plastic pots do not breathe, and the only route the water has is through the bottom drainage holes, which can often be blocked by circling roots.

Houseplant insects tend to be another problem. When plants are set outside for the summer, wind, rain and predator insects keep these pests in check. In the winter and indoors, none of those conditions exist and houseplant insect populations can really explode. One of the more common insects is the spider mite. When the infestations are bad, you can see webbing at the margins of the leaves and down in the axils where the leaf attaches to the stem. Another visual clue is that the margins of the leaves will yellow and brown due to the mite feeding on the tender cells at the edge of the leaves. Any new growth is highly susceptible. Put the plants in the sink or tub and use a strong force of water to dislodge the insects. Then, wipe down both sides of the leaves with a wet paper towel. These steps will do wonders. A spray of insecticidal soap also may be used. These mites are very small and easy to miss, so this will need to be repeated in a week, and possibly again, until no evidence of new feeding can be seen.

The other houseplant insect that is so easy to miss are scales. Outdoors, natural predators and the weather itself can keep scales under control (just like mites). However, once inside and away from those conditions, their numbers can grow quickly. Clues for scales are leaves will be sticky, as will the carpet or wood flooring beneath the plants. Young scales will not be dislodged with water, though the sap they are dripping is water soluble, so the plants will look better and floor clean-up is easy. The same insecticidal soap used on mites will cut through the scale cuticle and will be effective in control. Ditto on the repeated applications. (Remember, to always read and follow label instructions).

It may be winter, but there are still gardening plans and tasks to consider, and there are webinars available to brush up your skills or learn new things. Find upcoming webinars in horticulture, forestry, specialty crops, and more on the Illinois Extension website or in this helpful listing.

About the author: Richard Hentschel’s expertise extends across several subject areas with specialties in lawn care, fruit tree production, woody ornamentals, and home and community gardening. During his 45-year career in horticulture and agriculture, Hentschel became a well-known and respected expert for commercial and homeowner audiences, industry organizations, and media. He retired from University of Illinois Extension in April 2022 with nearly 30 years of service as a Horticulture Specialist and Educator in northern Illinois.