Those lovely houseplants that clean the air and add beauty to our homes are primarily tropical natives. In spring and summer, we can (sort of) convince them that they are still swaying in the breeze on the island from which they came. However, come autumn and winter in our cool northern climate, there is no more fooling them.
Houseplants enter a period of rest this time of year. Since they are not increasing their roots or sending up new shoots, they do not need fertilizer. In fact, continuing to fertilize can cause a buildup of salts in the soil that may harm your plants.
As a general rule of thumb, cease fertilizing houseplants from October until March. Begin again when you start to see new growth.
Water reduction is another consideration for winter houseplant care. Conditions are cooler and darker and, as a result, water evaporates more slowly. This is an excellent time to become the waterer that your plant would like you to be.
Rather than watering on a set schedule, regularly monitor soil moisture and, for most plants, only water when the top inch or more is dry. Doing this allows some oxygen to access the roots.
However, if a plant wilts before that point, take that as your cue to water that plant when its soil is still a bit moist.
When you do water, be sure to saturate the entire root ball. If you pour water over the soil and it drains out the bottom of the pot, you are doing it correctly.
Just dump the excess water out of the tray, or better yet, water your plants in a sink. This technique has the added benefit of flushing any excess fertilizer salts that may have accumulated.
Keep in mind that water is not the same thing as humidity. Most houseplants prefer a higher humidity level, but when we turn the heat on in our homes, the air can become inhospitably dry for them.
Houseplants that require higher humidity can be moved to a bathroom or have their pots placed on a tray filled with pebbles and water. Another way to increase the relative humidity around your plants is to cuddle several together. The water evaporating from the soil, as well as water loss through a plant’s leaves, will naturally give its neighbors some extra humidity.
If you witness signs of stress such as dropping leaves, the plant might be responding to a sudden change in temperature. You may need to find a temporary new home for that plant in the entryway that is not enjoying the gust of chilly air from the front door. Likewise, the high-light-loving plants could benefit from a move to a sunny windowsill, as long as their leaves are not touching the freezing windowpanes.
Treat the plants’ leaves as you do your other air filters and take some time to clean them so they can work as efficiently as possible. Dust and built-up greasy residue can be cleaned using a soft cloth moistened with tepid water and mild dish soap. Or, better yet, put the plants in the shower and rinse them off.
Most importantly, know what variety of houseplants you have and how they like to be cared for, and especially any winter modifications. Then feel free to join them for a little rest this winter!
For more information about houseplants, visit the University of Vermont Extension Master Gardener Garden Resources webpage (https://go.uvm.edu/garden-resources), click on the “Houseplants” tab to view the “Houseplant Heroes” video series and check out other resources.
by Amy Simone, Extension Master Gardener, UVM
Feature photo: High-light-loving plants may benefit from a move to a sunny windowsill during the colder months, providing their leaves do not come in contact with the freezing windowpanes. Photo by Amy Simone
