Unless you have a greenhouse and can artificially keep houseplants in active growth, it is best to let them rest a while.
Plants produce foliage in response to available light. This is because they use light in the manufacturing of food. When the amount of light drops below what the plant is used to, it cannot support the amount of tissue it has to produce and reacts by dropping its leaves. You can remedy the situation somewhat by providing as much light as possible inside to those plants that have been outside.
If you fertilized once or twice a month during the summer, only fertilize every six weeks, every two months or, even better, not at all. If you keep fertilizing at summer time levels, you run the risk of salt buildup, which can be detrimental to plants.
Any time of the year, watering is the most critical cultural practice you perform. But during the winter, it becomes even more critical. Plants need water, but they need oxygen in the root zone. Roots that are kept too wet will rot. In containers, water can be controlled in several ways.
Remember these points:
• Clay pots breathe, plastic ones do not.
• Heavy soil mixes stay wet longer that do light ones.
• Plants prefer a cycle of wet and dry. When you water a plant, water it thoroughly. Then let the soil approach dryness before watering again. Avoid watering plants with cold tap water. Research has shown that cold water destroys the ability of root cells to take in water and nutrients. Tests have shown that warmer water stimulates root growth.
Most houseplants are tropical and do not like it cold. Avoid drafts and heater vents because they can defoliate many plants. Avoid placing plants next to window panes, unless you have double paned or insulated windows.
Managing light, fertilizer, watering and temperature can help your plants pull through the winter in good shape until daylight increases and temperatures warm up again.