How to Prepare Your Houseplants for Winter After a Summer Outside

Watch the Weather

The mild temperatures that allowed your plants to thrive during the spring and summer can drop suddenly in the fall. Keep track of the weather forecast and move your plants well before the chance of frost. "Depending on where you live in the country, a good rule of thumb would be to bring houseplants indoors when the nighttime temperatures dip to 50 degrees," says Andrew Bunting, vice president of horticulture at the Pennsylvania Horticultural Society.

Check for Insects

About four weeks before bringing your plants inside, give them a once-over to make sure you aren't bringing any stowaway pests, like aphids, spider mites, scale, mealy bugs, or white flies into your home.

"Thoroughly inspect your plants for any signs of insects, including eggs that may have been laid on the leaves, under the leaves, or on stems," says Bunting. "If there are active insects, spray the insects with an insecticidal soap—it is critical that the insects get coated with the soap. This process should begin a month before bringing the plants into the house so you have enough time to spray, see the effects of your spraying, and then spray again if necessary."

Once your plants are inside, continue checking for any insects you might have missed—or that hatched once they experienced the warmer indoor temperatures of your home. "If this is the case, take your plant back outdoors if it is not too cold and treat it with insecticidal soap," says Bunting. "If this happens once it has gotten too cold outdoors, then take the houseplants and put them in the bathtub so that you can treat them with insecticidal soap."

Prune

Make the most of your outdoor space—and keep your indoor sinks and counters clean—by trimming, pruning, and repotting plants while they're still on your porch or patio. "Remove any dead, yellow, or discolored leaves, and if any pruning needs to be done, now is also a good time to do that," says Bunting. Continue to remove dead or damaged parts of the plant throughout the winter.

Repot Before Winter

Bunting cautions against repotting plants during the winter; it's better for the health of the plant—and for the cleanliness of your indoor spaces—if you do this before bringing the plants inside. "This is an opportune time to do any needed repotting," he says. "This is always a messy job, especially indoors, so take advantage of being outdoors and doing any necessary repotting. If plants have been sitting in saucers, empty the saucers of any water and also clean the saucer."

Choose a Sunny Spot

While your plant's light requirements will dictate where you put it once it comes inside, you need to factor in the changing sun exposure of autumn and winter. "As days get shorter, move sun-loving plants closer to a south-facing window to maximize sunlight," says Bunting. "If that's not possible, consider using supplemental grow lights. Rotate plants regularly to ensure all sides of the plant receive equal light." 

Avoid Heat and Cold

The same heaters that create an indoor atmosphere warm enough to keep your plants alive will provide too much heat if your plants are placed too close. "Heat from radiators or vents can dry out plants and cause leaf burn," says Bunting. And while many houseplants prefer slightly cooler temperatures, you should be looking for a mild room—not a cold spot. "Cold drafts can shock plants," says Bunting. While a sunny spot is good, place them away from doors and windows that are frequently opened.

Up the Humidity

Many houseplants prefer slightly moist environments; the warm, low-humidity air created by heating your indoor air can dry out the plant. "As you bring your plants indoors, they may react to the changing conditions by losing some leaves. Usually, this is just superficial, and the leaves will grow back," says Bunting. "As the months pass indoors, keep an eye out for leaves that might continue to discolor as the houseplants adapt." Support your plant as it adjusts to indoor air quality during the winter by adding moisture beyond simply watering: "Mist plants regularly, use a humidifier, or place plants on pebble trays filled with water," says Bunting.