After spending the spring, summer, and part of the fall tending to your garden and yard, you may be tempted to turn your attention towards the houseplants lining your windowsill. The colder winter months may seem like the ideal time to focus on your ferns, and fertilize your fiddle-leaf fig, but doing so may end up hurting your houseplants—not helping them. Here’s why you should hold off on fertilizing your indoor plants during the winter, and allow them to hibernate instead.
Most of the species we keep as houseplants are tropical natives, which is why they wouldn’t survive if you left them outside in a cold climate. But the change of seasons also affects their life indoors, according to Amy Simone, a master gardener at the University of Vermont Extension.
In climates with traditionally hot summers and cold, snowy winters, tropical houseplants feel more or less at home during the spring and summer months. But that changes once the colder weather of fall and winter hits, and the plants enter “a period of rest,” Simone explains.
The drop in temperature, coupled with decreased daylight hours this time of year result in reduced plant growth, according to a resource from the University of Maryland Extension. Because they’re neither expanding their roots nor sprouting new shoots, houseplants don’t need fertilizer during the winter.
But surely a little fertilizer can’t hurt, right? Actually, it can, says Simone. Unnecessary or excessive fertilizer can lead to a buildup of salts in the soil, which can end up harming the plant.
If you’ve already fertilized your houseplant during the winter and now notice white, chalky salt deposits on the surface of the soil or the outside of the pot—or that your plant is yellowing, wilting, or browning at the tips—that’s probably a sign of high soluble salt levels, according to another resource from the University of Maryland Extension.
The good news is that you can fix this pretty easily by flushing the soil with clean water, allowing it to run out the bottom of the pot, and repeating the process until you’ve flushed it with at least as much water as the pot holds (e.g. two gallons of water for a two-gallon pot).
It may seem like a long time, but Simone recommends going the entire winter without your fertilizing tropical houseplants. You’ll know it’s time to start fertilizing again when you spot signs of new growth, which, she says, typically happens around March.
