Overwintering Houseplants

Before frost nips your garden, turning leaves and stems to mush, you’ll need to bring in any houseplants that have been enjoying the fresh air and sunshine outdoors. But a sudden change in light and humidity levels can shock your plants, causing them to drop foliage, wilt and even die. Before you move them inside, try these tips to ease the transition and keep them healthy:

• A couple of weeks before the temperatures dip to 45 degrees F or below in your area, move your potted plants underneath a tree or onto a covered porch, so they can start adjusting to the reduced light they’ll get in your home. (Some tropicals can be damaged at 50 degrees F or below, so move them even earlier.) Another option: bring plants indoors while you still have your windows open.
• Avoid repotting before moving your plants inside. Growth typically slows during the fall and winter, so save that chore for spring. If your plants are large, take cuttings to bring in and root instead. Otherwise, cut back tall, leggy stems.
• If pests have gotten onto your plants—and they may be hiding under the leaves, even if you don’t see them--gently spray the plants with water from the garden hose, or put them under a gentle, tepid stream of water in the shower. You can also use an insecticidal or horticultural spray. If the plants are heavily infested or diseased, discard them. They probably won’t survive anyway, and you don’t want to bring in problems that may spread.
• To flush out pests from containers, soak your potted plants in a bucket or tub of warm water mixed with a few drops of mild dishwashing liquid for about 15 minutes. Do not soak plants that prefer drier soils, like cacti or succulents, or plants that go dormant for the winter.
• Clean the windows where your plants are going to sit. Accumulated grime can reduce the amount of light they get. Try to give them roughly as much light as they received outside.
• Pick a spot for your plants away from furnace vents, heaters and drafts. Keep them away from doors that will be opened frequently.
• If the light coming through your windows isn’t bright enough, supplement it with fluorescents or grow lights. Set timers to give your plants a rest period—that is, some darkness--every day.
• Rotate plants growing under artificial lights. Light is usually more intense from the center of the bulbs than from the ends.
• To raise the humidity around your plants, group them together, or keep them near the kitchen sink or in a steamy bathroom. You can use a cool vaporizer, too, or sit pots on trays or saucers filled with pebbles and some water. Just don’t let the bottom of the pots sit in the water. Constant moisture can cause plant roots to rot.
• Remember that plants grow more slowly in reduced light, and over watering is a primary reason that houseplants die, so cut back on watering. Some plants won’t need fertilizing until they begin actively growing again in spring. 
• When warm weather returns, acclimatize your plants by reversing the process of bringing them indoors. Let them spend a week or two in a shaded spot before exposing them to the sun and wind.