Why the rules change when the clocks go back

By late October, a windowsill that was flooded with light in June is receiving a fraction of what it did. Across most of the UK, daylight falls from around sixteen hours at midsummer to under eight by December, and the light that does arrive is weaker and often filtered through grey cloud. For your houseplants, that is the difference between a growing season and a long, slow rest.

Almost everything about indoor plant care is governed by light. Less light means slower photosynthesis, which means less demand for water and nutrients, and slower growth above and below the soil. So the single most useful thing you can do between October and March is to treat light as the limiting factor and adjust everything else around it. Get that right, and most plants will sail through to spring without a single drama.

Move plants closer to the window

Light intensity drops off dramatically with distance from glass — a plant sitting two metres back from a window may be receiving a small fraction of what one on the sill gets. Where you have space, bring plants to within about 30–60cm of the glass, and prioritise your sun-lovers: succulents, cacti, citrus, jade plants, rubber plants and most flowering types.

• Lift them up. A plant stand, stool or upturned pot raises foliage into the brightest band of light, which is usually around windowsill height rather than floor level.
• Clean the glass. A surprising amount of winter light is lost to grime, condensation marks and net curtains. A quick wipe inside and out makes a genuine difference.
• Rotate a quarter turn each week. Growth will lean hard towards the window otherwise, and you will end up with lopsided plants by March.
• Mind the cold. Leaves pressed against single-glazed panes can be damaged on frosty nights, so pull pots back a few centimetres after dark, or line the sill with a piece of card.
• Watch the radiators. A spot above a radiator is warm and dry — fine for a cactus, punishing for a fern or a calathea.

If you have a dim corner with no decent natural light at all, a simple LED grow light on a timer for six to eight hours a day will keep foliage plants ticking over. Even a modest one beats a north-facing wall in December.

Ease off the watering can

Overwatering, not neglect, is the most common way houseplants die in winter. Compost that dried out in three days in July may take three weeks now, and the roots are drinking far more slowly. Before you water, push a finger two or three centimetres into the compost, or judge by weight: a light pot needs water, a heavy one does not.

• Water less often, and consider giving slightly less each time rather than soaking as you would in summer.
• Always empty the saucer or outer pot after half an hour — standing water is a root-rot trap in cool conditions.
• Use room-temperature water. Cold tap water straight onto tropical roots is a shock they do not need.
• Let cacti, succulents and most snake plants go almost completely dry between waterings, and water sparingly at that.
• Cool rooms slow drying further, so reduce frequency again if a room sits below about 16°C.

Reduce feeding, or stop altogether

Most houseplants are not actively growing from roughly October to February, so there is little point in pushing fertiliser at them. Feeding a resting plant can lead to a build-up of salts in the compost, weak, spindly growth and scorched leaf edges. As a rule, stop feeding altogether from mid-autumn and start again in March, when you see new growth unfurling.

There are exceptions. Plants kept under grow lights, winter-flowering types such as Christmas cactus, and anything still pushing out leaves will appreciate a weak feed — around half the strength recommended on the bottle — every four to six weeks. If in doubt, skip it. A hungry plant recovers; an overfed one often does not.

Read the leaves: what yellow is telling you

Yellow leaves in winter are a symptom, not a diagnosis, and the fix depends entirely on the rest of the picture. Before you do anything, look at the compost, the position of the yellowing, and how many leaves are affected.

• One or two yellow leaves low down, dry compost: usually normal ageing or a light-hungry plant shedding what it can no longer support. Remove them and improve the light.
• Widespread yellowing with soggy compost: classic overwatering. Stop watering, move the pot somewhere bright and airy, and let it dry out properly.
• Yellow, curling leaves on a windowsill plant: often cold damage or draughts. Move it back from the glass.
• Pale, stretched, small new growth: a straightforward light shortage. Move it closer to the window.
• Crisp brown edges with yellow halos: dry air from central heating. Group plants together or stand pots on a tray of pebbles with water beneath.

Small comforts that make a real difference

Grouping plants closely creates a microclimate of higher humidity, which suits ferns, philodendrons and other jungle natives far better than a lonely spot in a dry room. Dusty leaves also block light, so give foliage a gentle wipe with a damp cloth every few weeks — you will be surprised how much brighter a plant looks, and how much more light it can actually use.

Finally, check leaf undersides and the joints where stems meet leaves whenever you water. Warm, dry indoor air encourages spider mite and mealybug, and catching them early in November is far easier than fighting an infestation in February. Look after the light, go easy on the water and the feed, and your plants will be ready to surge away again when the days finally lengthen.