One would think houseplants would not suffer during the drab days of winter. Unfortunately, winter is a stressful time for them, too.
The short days and low light levels are the primary causes of houseplant problems. The light deficit creates stress, which the plants respond to by slowing down or stopping growth. This is evident in yellowing leaves or, in many cases, excessive leaf drop.
It is not just the shorter days that influence the plant’s growth but also the quality of light. The sun’s winter orbit is closer to the horizon, and this limits the spectrum of light that gets through.
Often in our zeal to make the plants healthy, we supply additional food and water. These extras actually create more problems than they solve.
When growth slows, excess water and nutrients weaken the plant by damaging the root system. The winter months are a time to reduce watering as the slowed growth means less uptake.
Fertilizers just stay in the soil, where these nutrients can build up and burn the roots by creating salts. It is not recommended to fertilize houseplants from fall through early spring.
The best thing to do for ailing houseplants during the winter is to increase the light levels. This could mean moving them to a sunnier window or providing a light source.
If artificial light is used, there are some guidelines.
Artificial light is only beneficial if the light source is close to the plant, within a foot or so, and left on for at least 14 to 16 hours. A lamp a few feet away or an overhead light will provide no advantage. Artificial light is not practical for most people.
As better light returns in the spring, plants will start to collect more energy and grow. Fertilization is beneficial at that time.
Plants that have dropped leaves may need to be pruned back to reduce legginess and promote new vigorous growth.
One last word of caution: Don’t be tempted to boot the plants outside on warm winter days or early in the spring. Houseplants are tropical, so temperatures below 55 degrees can lead to more leaf drop.
Come spring, all the plants will benefit from longer days and warmer temperatures. The same could be said for most of us as well.
Dennis Patton is a horticulture agent with Kansas State University Research and Extension. Got a question for him or other university extension experts? Email them to firstname.lastname@example.org.