Why You Shouldn’t Fertilize Indoor Plants in Winter
After spending the spring, summer and part of the fall tending to your garden and yard, you may be tempted to turn your attention to the houseplants lining your windowsill. The cold winter months may seem like the ideal time to focus on ferns and fertilize your figs, but this could end up harming your houseplants rather than helping them. This is why you should refrain from fertilizing your houseplants during the winter and instead allow them to go dormant.
Why you shouldn’t fertilize indoor plants in winter
Most of the species we keep as houseplants are tropical natives, so they will not survive if left outside in cold climates. But the changing seasons also affect their indoor life, according to Amy Simone , a master gardener at the University of Vermont.
In climates with traditionally hot summers and cold, snowy winters, tropical houseplants are more or less at home during the spring and summer months. But the situation changes when the colder days of autumn and winter arrive and the plants enter a “dormant period,” explains Simone.
According to a resource from the University of Maryland , lower temperatures combined with shorter daylight hours this time of year result in slower plant growth. Since houseplants do not expand their roots or produce new shoots, they do not need fertilizer in winter.
But a little fertilizer won’t hurt, right? Actually, it can, says Simone. Unnecessary or excessive fertilizers can cause salts to build up in the soil, which can harm the plant.
If you’ve already fertilized your houseplant over 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—this is likely a problem. According to another source from the University of Maryland , a sign of high levels of soluble salts.
The good news is that you can easily fix this by rinsing the soil with clean water, letting it drain to the bottom of the pot, and repeating the process until you have flushed it with at least as much water as the pot will hold. (for example, two gallons of water per two-gallon pan).
When to start fertilizing houseplants again
This may seem like a long time, but Simone recommends going the entire winter without fertilizer for tropical houseplants. You’ll know it’s time to start fertilizing again when you notice signs of new growth, which she says usually happens around March.