Birthday
HydrangeasOnce the heating comes on, many houseplants start to brown at the leaf edges, drop buds and fall ill more often. It is not just the cold outside: hot radiators dry the air, while on the windowsill the roots may be chilled by cold glass at the same time. Here is how to help your plants through the heating season.
Plants to enjoy in winter: potted plants.
Why plants struggle in winter
- Dry air. During the heating season indoor humidity often drops to 20–30 %, while most tropical plants prefer 50 % or more.
- Temperature swings. Leaves overheat above a radiator, while cold glass and airing the room chill the plant.
- Too little light. Short days slow growth, yet in a warm room the plant keeps trying to grow, producing weak, stretched stems.
- Pests. Spider mites and thrips multiply quickly in warm, dry air.
Warning signs
Brown, crispy leaf tips and edges, dropping buds, curling leaves and fine webbing on the undersides of leaves all mean it is time to change the conditions.
What to do
- Move plants away from radiators, ideally by half a metre; on a sill above a radiator, a board or foam sheet stops hot air hitting the pots.
- Raise humidity. A room humidifier works best. Pebble or clay-ball trays and grouping plants also help. Misting has only a brief effect, and hairy-leaved plants such as African violets should not be misted.
- Protect roots from cold. On a cold windowsill stand pots on cork or foam mats.
- Water according to the soil. Near a radiator compost dries faster; by a cold window, slower. Use room-temperature water.
- Air the room without draughts. Move sensitive plants away from an open window while airing.
- Add light. Move plants closer to the window or use a grow light, and cut back on feeding in winter.
- Check the leaves. Look under the leaves weekly for mites and wipe them with a damp cloth.
Who suffers most
Moisture-loving tropical plants find dry air hardest: prayer plants, calatheas, ferns, the bat flower and azaleas. Succulents and cacti, on the other hand, cope with winter indoors much better. More common care mistakes in “Houseplant care mistakes”.
FAQ
Does a wet towel on the radiator help?
It raises humidity a little, but less than a humidifier, and the towel needs frequent re-wetting.
Should I water more often in winter?
It depends on the spot: near a radiator perhaps yes, by a cool window less often. Always check the soil with your finger.
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Author: Maria Svitlovir
Graduated from Taras Shevchenko National University of Kyiv, Institute of Biology and Medicine (2001). BSc in Biology, MSc in Horticulture. Writes about plants, works at a garden centre selecting and repotting plants, and contributes to plant reference guides.
