Before Bringing Plants Inside for Winter:
1) Check your houseplants thoroughly for small insects like aphids, mealybugs and spider mites, and remove them before bringing plants back inside. Soaking the pot in a tub of lukewarm water for about 15 minutes will force insects out of the soil. Also check the bottom of pots for snails, earthworms, or other insects, Treating the plants with neem oil can help as well.
2) If necessary, repot plants into larger containers. If plants have gotten leggy during their outdoor stay, remove from the container, and prune the top and roots in equal proportions.
3) To prevent shock when you bring houseplants back indoors, expose plants gradually to reduced lighting. Usually, if they've been in bright light and you move them into much lower light, expect some leaves to fall off. However, new ones should form as the plants readapt to the lower light. It’s best if they've been outside in high light to put them in similar light indoors, like a south window or under plant lights on a timer for 16 hours a day.
4) Don't overwater! Let the soil surface get dry to the touch before watering again. If in doubt, don’t water. Water succulents less often, when the soil is dry for several days. Don’t water if quite cloudy or rainy weather, as plants won’t get sufficient light indoors to dry out.
5) Finally, give your plants a boost of fertilizer, according to the directions on the product label. Plants that have been repotted with soil containing fertilizer will not need to be fed again for two to three months, or according to label directions. Keep in mind that often plants grow more in winter indoors, receiving more light between snow reflection and leaves off of trees.