As we’re getting deeper into fall, fewer daylight hours naturally signal to your houseplants that it is time to slow down. What many houseplant growers want to know, though, is what to do about fertilizing your plants during this transition period: do you gradually slow down on fertilizing? Or stop completely as soon as the weather gets cooler and the days get shorter?

“Overfeeding can do more harm than good,” explains Donna Letier, co-founder and CEO of Gardenuity. But what exactly counts as overfeeding? Fortunately, there is an easy formula for fertilizing your houseplants correctly once the days start growing shorter.

How Often Do Houseplants Need Fertilizing in Fall?

As daylight wanes, indoor plants experience a natural drop in photosynthesis. Without the high light levels and vigorous growth of spring and summer, a plant’s metabolic processes decelerate, meaning its demand for additional soil nutrients drops sharply.

While a regular feeding schedule is crucial during active growth, fertilizer requirements shift as the weather turns cool. As a rule of thumb, most houseplants need to be fed every second watering during the growing season, or every 10–14 days in spring and summer. In autumn and winter, houseplants don’t need as many nutrients and can be fed every fourth watering, or once a month.

In fact, many houseplant experts will tell you that there’s no need to fertilize your houseplants at all between the months of October and March. According to the University of Illinois Urbana-Champaign Illinois Extension, most indoor plants “usually need very little or no additional fertilizer” during this time.

The Danger of Overfeeding During Dormancy and Rest

It can be tempting to offer fertilizer at the first sign of a drooping or sluggish plant, but heavy nutrient applications during a resting phase often trigger plant stress. “When a plant is stressed, it’s not focused on growth,” cautions Letier.

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Commercially sold plant fertilizers are typically made from soluble salts, and unused fertilizer salts build up in the potting soil. Over time, these concentrated salts draw moisture away from the roots, causing chemical burn and foliage damage.

Instead of forcing growth when a plant is trying to rest, adjusting your feeding routine prevents fertilizer toxicity and allows the root system to survive the winter.

How to Safely Adjust Your Fall Fertilizing Schedule

You can simply stop fertilizer application whenever your plant enters its dormant state. But if you prefer to carry on applying fertilizer, there are a few adjustments you should make to do it safely:

• Dilute Your Fertilizer Mix: Instead of feeding monthly at full strength throughout fall and winter, Letier recommends cutting back to a diluted mix every six weeks.
• Observe Active Growth: If your plants are housed under intense artificial grow lights and actively pushing out new leaves, they may continue to take up mild nutrients. However, plants relying on ambient window light should have their feeding spaced out significantly or stopped completely.
• Withhold Food from Stressed Plants: Never attempt to use fertilizer as a remedy for a struggling or sunburned plant. Letier advises skipping fertilizer entirely if plants are showing signs of sunburn or root stress.

By shifting to a light, six-week diluted schedule—or pausing fertilization entirely when plants enter deep rest—you protect your indoor garden from root burn and help you plants stay healthy, resilient and ready to bloom come spring.

Sources:

• Donna Letier, co-founder and CEO of Gardenuity

This article has been adapted from Are You Making These 5 Common Indoor Plant Mistakes? by Ashley Zlatopolsky.

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