How to Care for Indoor Plants Through Winter

Why Winter Changes the Rules

Winter catches British houseplants out — not because it is cold outside, but because our homes turn dark, dry and oddly warm. Growth slows to a crawl, light at a north-facing window can fall to a fraction of its June strength, and the central heating hums away for hours at a time. Most of the plants we keep indoors are tropical by origin, happiest in humid, steady conditions. A UK sitting room in January is none of those things.

Understanding this is half the battle. A plant that is barely growing needs far less water, almost no food and every scrap of light you can give it. The vast majority of winter houseplant deaths come from well-meaning care that would be perfect in July and fatal in December. Change a few habits now and you will be rewarded with glossy, robust plants when the light returns.

Water Far Less Than You Think

Overwatering is the single biggest killer of indoor plants between November and March. Compost that sits damp in cool, low-light conditions has nowhere to dry out, and roots begin to rot long before the leaves admit anything is wrong.

• Test before you pour. Push a finger two or three centimetres into the compost. If it feels even slightly moist, wait.
• Stretch the intervals. A plant watered weekly in summer may only need a drink every fortnight or even every three weeks now. Cacti and succulents can often go six to eight weeks.
• Water in the morning. Any surplus has the day to evaporate rather than sitting around the roots overnight.
• Empty the saucers. Never let a pot stand in water for more than ten minutes. If in doubt, tip it away.
• Use tepid water. Straight from the cold tap is a shock to tropical roots. Let it stand in the watering can for an hour first.

If you are unsure whether a plant needs water at all, err on the side of waiting another few days. Very few houseplants die of thirst in a British winter.

Keep Pots Clear of Draughts and Radiators

Position matters more now than at any other time of year. A windowsill gives you precious light, but the glass itself can drop close to freezing on a clear January night, and the chill seeps through the pot. Equally, a spot directly above a radiator will cook leaves and dry the air to a crisp.

• Move pots a little way back from the glass at night, or line the sill with a piece of thick card or cork to insulate the base.
• Avoid doorways, hallways and open trickle vents where cold air funnels past. Ficus, calathea and peace lilies will drop leaves within days.
• Shield plants from radiators with a shelf or screen, or shift them to a cooler room that still gets decent light.
• Aim for 16–20°C. Most houseplants prefer a steady, slightly cool room to a stuffy one, and they dislike sharp swings between day and night.

Turn each pot a quarter turn once a week so growth does not lean permanently towards the window.

Clean Leaves and Lift the Humidity

Dust builds up quietly and blocks the light that leaves need to make energy. A plant that looks dull in winter is often just grubby. Wiping is also the perfect opportunity to spot pests early.

• Wipe smooth leaves with a soft damp cloth or a sponge, supporting each leaf with your other hand. Do this every couple of weeks.
• Brush fuzzy leaves such as African violets or begonias with a soft dry paintbrush instead — water sits on them and causes spots.
• Group plants together so they share the moisture they release, but leave a little air between pots to prevent mould.
• Stand pots on a tray of pebbles with water kept below the pebble line. As it evaporates, humidity rises around the leaves.
• Skip misting most plants. It raises humidity for minutes only and can leave unsightly marks. A tray or a nearby bowl of water works far better.

Ease Off the Feed and Delay Repotting

Fertiliser encourages soft new growth that weak plants cannot support in poor light, and excess salts linger in compost that is rarely flushed through. Stop feeding most houseplants from October until you see fresh growth in late February or March, then restart at half strength.

The exceptions are plants in flower — a Christmas cactus, for instance — and anything growing under a bright lamp, which can take a weak feed once a month. Repotting is best left until spring too. Roots are dormant, and fresh compost around inactive roots simply stays wet.

Watch for Pests and Rot

Warm, dry indoor air is heaven for red spider mite, which shows up as fine webbing and speckled, faded leaves. Check the undersides of leaves weekly. Mealybugs appear as small white cottony blobs in leaf joints, while fungus gnats hover above permanently damp compost.

• Isolate any affected plant straight away so the problem does not spread along the shelf.
• Wipe pests off with a damp cloth or a cotton bud dipped in mild soapy water, and repeat weekly until they are gone.
• Let the top of the compost dry out to break the fungus gnat cycle.
• Act on rot fast. Yellowing leaves, a soft blackened stem base and a sour smell mean soggy roots. Stop watering, remove damaged foliage and let the compost dry before resuming a much lighter regime.

Winter care is mostly about doing less, more thoughtfully. Cut the water, guard the position, keep the leaves clean, and your plants will sail through to spring.