By the time February turns to March, most British homes have been shut up against the cold for months. Windows stay closed, radiators run hot and daylight is measured in hours rather than afternoons. Houseplants that looked glossy in October often greet the new season with yellowing leaves, crispy edges and a general air of resignation. The good news is that most of them are not dying — they are simply exhausted. With a bit of patience and a few careful steps, the majority will bounce back strongly by late spring.

Why a dry winter indoors is harder on plants than it looks

It helps to understand what your plants have actually been through. Central heating does two things at once: it warms the air and strips moisture out of it. Relative humidity in a heated living room can easily drop below 30 per cent, which is roughly the atmosphere of a desert. Plants that evolved in humid jungle understories respond by losing water through their leaves faster than their roots can replace it.

At the same time, light levels fall dramatically. Even a bright south-facing windowsill receives a fraction of its summer intensity in December. Less light means slower growth, which means the plant needs far less water — yet many of us carry on watering at autumn levels, or forget entirely and let compost bone dry. Both extremes stress the roots, and stressed roots cannot support healthy leaves.

Start with the roots, not the leaves

Before you touch a single leaf, look below the soil line. The root system tells you far more about a plant's condition than its foliage does.

• Tip the plant out gently — support the stem between your fingers, turn the pot upside down and ease it free. If it resists, run a knife around the inside rim.
• Healthy roots are firm, pale and smell faintly of earth.
• Rotting roots are brown or black, mushy and smell sour or sulphurous. Trim these away with clean scissors, cutting back to firm white tissue.
• Bone-dry rootballs that pull away from the pot mean the compost has become hydrophobic and is repelling water. Soak the whole pot in a bowl of tepid water for twenty minutes, then let it drain thoroughly.
• Fungus gnats hovering around the surface usually signal compost that has stayed wet too long. Let the top few centimetres dry out between waterings and the population will fall away.

If the roots are sound, resist the temptation to repot. Repotting is a shock at the best of times, and a struggling plant does not need one now. Wait until active growth resumes in April or May.

Trim damaged foliage — but not too much

Brown, crispy leaf edges will never turn green again, and they are a drain on the plant's resources. Cut them away cleanly with sharp scissors, following the natural shape of the leaf where you can. On plants with long strap-like leaves, such as spider plants or dracaenas, trim the dead tip into a point so the cut looks deliberate.

Remove any leaves that are fully yellow, mushy or dropping. Beyond that, be conservative. A plant that has lost half its leaves in winter may only have enough stored energy for a handful of replacements, so leave anything that still has a decent patch of green — even a tatty leaf is still photosynthesising. Also clear away fallen debris from the compost surface, which otherwise harbours mould and pests.

Rethink your watering before you do anything else

Watering is where most winter damage happens, so change your habits before you change anything else. Forget the calendar and use your finger instead: push it two or three centimetres into the compost. Water only when it feels dry at that depth.

• Use water at room temperature — straight from a cold tap is a shock to tropical roots.
• Water thoroughly until it runs out of the drainage holes, then empty the saucer. Never let a pot stand in water.
• Small pots in warm rooms may still need water weekly; large pots in cool hallways may need it monthly.
• Cacti and succulents should be watered sparingly until March, then gradually brought back.
• If your tap water is hard, leave it to stand overnight or use filtered water for ferns, calatheas and spider plants, which resent lime.

Hold off on the feed

It is instinctive to reach for plant food when something looks poorly, but feeding a stressed, semi-dormant plant is like offering a heavy meal to someone recovering from flu. The roots cannot take it up, and unused salts build up in the compost, burning what healthy root there is.

Wait until you see clear signs of new growth — a fresh unfurling leaf, a new shoot, a green tip pushing through. Only then begin feeding, at half the recommended strength for the first month. Plants under grow lights or in a very sunny conservatory may be ready in March; a shady north-facing bedroom might not be until May.

Give it light, humidity and time

Move plants closer to a window as the days lengthen, but keep them clear of radiators, draughts from doorways and the cold glass itself at night. Grouping plants together creates a small pocket of humidity, and a tray of pebbles with water beneath the pots helps too — just make sure the pots sit above the water line. A weekly misting is pleasant but of limited value; raising background humidity does far more.

Finally, be patient. A plant that has been through a long, dry winter will not recover in a fortnight. Give it six to eight weeks of consistent, gentle care — the right light, careful watering, no feeding too early — and you will be rewarded with new growth just as the season turns. Slow rehabilitation always beats a dramatic rescue.