Houseplants need special care over the winter when the temperature and light levels drop. Pelargoniums also have particular care needs. We tell you what to do so that your plants make it through.
Come inside out of the cold
Houseplants that have been outside for a summer holiday should be back indoors now. Most plants will be slowing down now, and some will become dormant. That’s because, from late autumn to early spring, there’s less light around.
Make sure your plants get as much natural light as possible
If you can, move your houseplants into a sunny conservatory or porch to give them light from different directions. A west or south-facing windowsill is good. And clean your windows inside and out to max the light. (I definitely must do this.)
Gradually reduce watering, and stop feeding
Dormant plants need very little water and no food so gradually reduce watering to once a fortnight or when the compost is almost dry. Check carefully on plants near radiators or fires.
Succulents only need water every two to three weeks, and cacti need none at all in winter.
If you give houseplants too much water in the winter they will either produce weak growth or rot and you don't want either.
Plants growing vigorously, or flowering like Christmas cacti and poinsettias, are not dormant so they should be watered when the compost feels dry.
Clean their leaves
Plants that have been outside have enjoyed rain showers cleaning off their leaves. Their indoor friends haven’t been so lucky. Light is already limited now and dirt on the leaf reduces the amount of light reaching its surface even more, making it very hard for plants to photosynthesise food. Wipe off dust regularly with a damp cloth, or give the plant a gentle lukewarm shower for five minutes or so.
Keeping Goldilocks Houseplants at just the right temperature
- Houseplants don’t like big changes in temperature: 12-18C is just right (a little too cool for most of us in the winter).
- They don’t like it too hot. Keep them away from open fires and radiators, and move them out of overheated rooms.
- They don’t like it too cold. Don’t leave them on the windowsill behind the curtains as this traps them in cold air all night.
- They don’t like draughts. Make sure they aren’t near open windows or doors.
- Tropical plants especially don’t like dry air; they need the atmosphere to be humid. Place them on a tray of damp gravel or mist them daily. Group plants together to create a humid microclimate around their leaves.
Plant pests love being inside in the warm over the winter and take the opportunity to breed. Check all of your plants thoroughly for pests, but especially check plants that spent the summer outside. Look at both sides of the leaves, and remove any pests you find. Keep checking throughout the winter.
Keeping pelargoniums over the winter
If you’d like to carry your pelargoniums on to next year you have three, perhaps four, overwintering choices:
- take cuttings and grow them on indoors or in the shed or greenhouse
- overwinter plants in containers in greenhouses or garden frames or a sunny shed windowsill
- overwinter in a semi-dormant state, giving them a complete rest, somewhere cool, dark and frost-free.
More from the Royal Horticultural Society about overwintering pelargoniums, and from Dr Hessayon.
There is a fourth choice - to keep them going as they are! Zonal pelargoniums will flower as long as there is good light and the temperature is at least 7-10°C. I mentioned my local café's all-year-round pelargoniums in an earlier post. My co-blogger has a three year old pelargonium on a kitchen windowsill that just keeps on going. Don’t overwater them and their flowers will brighten the darker days. Cut them back to new shoots and feed them in the spring, ready for the new season's growth.
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