For many house plants, the decreasing light levels in late autumn are a cue to enter a dormant phase, in preparation for making it through a potentially tough winter ahead.
If you continue to water and feed them as you do in summer, this will encourage them to keep on growing, putting them under strain and leading to weak, spindly growth.
Dormant plants need very little water – too much and they’ll either produce soft, weak growth or will rot as water accumulates in the compost. For most house plants, reduce watering to once every fortnight. For succulents, only water every two to three weeks, and for cacti, stop watering entirely. The exception is winter-flowering plants, such as Christmas cacti and poinsettias, which need watering whenever the compost feels dry.
Move into the light
With shorter days and less sunshine over winter, it’s important to maximise the amount of light reaching your plants. Ideally, move them into a sunny conservatory or porch, so they get light from several directions. If you don’t have these, then move your plants onto a west- or south-facing windowsill. It’s also worth cleaning your windows inside and out to let in as much light as possible.
Clean their leaves
Indoor plants, such as snake plants, often accumulate a thick layer of household dust on their leaves. This reduces the amount of light that can reach the leaf surface, making it harder for them to manufacture food. Wipe off dust regularly using a damp cloth, or stand the plant in a luke-warm shower for five minutes. Leaf-cleaning products are available, but are only suitable for use on certain plants.
Keep them warm
Most house plants need a temperature of 12-18°C. They dislike large temperature fluctuations, so position them away from cold draughts and open windows or doors. If they’re on a windowsill, leave the curtains open if you can, as they trap cold air at night. Alternatively, move plants off the windowsill at night. Also keep plants away from heat sources such as radiators and fireplaces, which can scorch delicate foliage.
Check for pests
A nice cosy house provides the perfect environment for many plant pests like aphids, scale insects, thrips and mealybugs to thrive and breed over the winter. Inspect all your plants thoroughly for pests now, looking under the leaves and as well as on top. Check plants that have spent the summer out in the garden particularly well, so you don’t introduce new pests, and remove any that you find. Keep inspecting your plants regularly throughout the winter.