by Diana Alfuth, horticulture educator for Pierce and St. Croix counties UW-Extension
January and February are probably your houseplants’ worst months. While we northern Wisconsinites dream of a winter vacation in warm, sunny places, your houseplants can only sit and wait for better conditions to come to them. Winter’s short days, low light levels, and dry air are hard on houseplants. And, by now your plants’ leaves may have accumulated dust and your windows may be in need of washing. Dirty windows block even more light.
To help your plants make it through their worst winter months, inspect and treat plants for any insects, such as mealybugs, scale, or aphids that may have appeared. Clean off any accumulated dust by wiping each individual leaf with a damp cloth or giving them a shower. Small plants can be washed in the kitchen sink with a sink sprayer. Large plants can go in your shower. I recommend covering the soil surface with aluminum foil to prevent the potting mix from splashing out or getting waterlogged.
Next, wash your windows inside and out. Even though it’s cold outside, when the sun hits the window you can wash the outside without your cleaning solution freezing.
If your plants are looking stressed with sparse or light-colored foliage, try adding supplemental light. Even a table lamp with a fluorescent bulb above the plant can add extra light to get your plant through winter in better shape.
Normally, you do not want to fertilize houseplants from October through January because with low light levels, plants will not be growing. Fertilizers can build up in the soil and damage roots, or they can force plants into spindly, weak growth. But by the end of February, with the days getting longer and the sun getting higher and stronger, pinch back leggy growth and give your plants their first fertilizer of the year to help them put on new, vigorous growth.