How to care for houseplants in winter

Winter is the hardest season for houseplants. The days are short, heating dries the indoor air and windows can be cold — while most plants rest and grow slowly. In Finland the dark season is long, and in northern Lapland the sun doesn’t rise at all for a while.

The short answer: houseplant care in winter comes down to four changes — water less, give your plants as much light as you can, keep them away from radiators and cold glass, and skip fertiliser until spring.

Below you’ll see how to do each in practice, how to spot trouble early and how to bring a new plant home safely in freezing weather. Needs vary by species — a cactus and a fern want very different things — so when in doubt, check the care instructions for your plant.

Water less than in summer

When plants grow slowly, they use less water. Overwatering is the most common reason houseplants struggle in winter, because wet soil and low light make the roots rot. A plant that needed weekly watering in July may need it far less often in January.

Water when the top layer of soil has dried — check it with your finger instead of following a fixed schedule. Lifting the pot helps too: a dry pot feels clearly lighter than a freshly watered one.

When you do water, water thoroughly so the whole root ball gets wet. Empty any water left in the saucer after a while, because roots standing in water can’t get air. Use room-temperature water — tap water can be very cold in winter, so let it stand in the can first.

A few exceptions are worth knowing. Cacti and most succulents need very little water during their winter rest. Moisture-loving plants such as ferns shouldn’t dry out completely. And a plant that keeps growing under a grow light or in a warm, bright spot may need more water than its neighbours.

Give them as much light as you can

Light is the scarcest resource in a Nordic winter. A spot that was bright enough in summer can be far too dark in December, and a north-facing window lets in very little light at this time of year.

• Move plants closer to the window, ideally a south- or west-facing one.
• Wipe dust off the leaves so they can use the light they get.
• Wipe the inside of the windows, too — dirty glass lets less light through.
• Take down sheer curtains for the winter or move the plants in front of them.
• Turn the pots now and then so the plant doesn’t lean towards the light.
• Consider a grow light for plants that need a lot of light.

If your home is dark, a grow light helps most. A simple LED grow light is enough for most homes: place it at the distance the manufacturer recommends and use a timer for a regular daily rhythm. Switch it off at night — plants need darkness, too.

Signs of too little light are long, pale stems, small new leaves and a plant stretching towards the window. Move it somewhere brighter or add light — more water or fertiliser won’t fix it.

If your cat likes to sit on the windowsill, check whether the plants you move there are safe for pets. Some common houseplants are toxic to cats and dogs.

Protect them from dry air and cold

Keep plants away from radiators and hot air, which dry the leaves, and away from cold window panes and draughty doors. Leaves touching a cold window can get damaged.

In many homes the radiator sits right under the window, so the windowsill is both the brightest and the driest spot in the room. A plant stand just in front of the window is a good compromise: almost the same light, but out of the warm air rising from the radiator.

Be careful when you air the room. A window or balcony door left open in freezing weather can damage tropical plants quickly, so move them out of the cold draught or keep the airing short.

Grouping plants together raises the humidity around them. A tray of pebbles and water under the pots helps too — just make sure the pot stands on the pebbles, not in the water. If your indoor air is very dry, a humidifier helps both you and your plants. Misting the leaves raises humidity only for a moment, so it isn’t enough on its own.

Let them rest

Most houseplants don’t need fertiliser in winter. A slowly growing plant can’t use the extra nutrients, and unused fertiliser can build up in the soil. Start feeding again in spring, when the days get longer and new growth appears.

Wait for spring to repot as well, unless the plant has a clear problem now — for example root rot, a broken pot or roots that fill the pot so tightly that water runs straight through.

The same goes for bigger pruning. It’s tempting to cut back stems that stretched during the winter, but the plant grows back fuller if you prune it in spring. You can remove yellow or dead leaves at any time.

Keep an eye out for pests

Warm, dry indoor air suits many pests, and winter is often when plant owners first notice them. Check your plants every time you water, especially the undersides of the leaves.

• Spider mites: fine webbing and tiny pale specks on the leaves. They thrive in dry air.
• Fungus gnats: small black flies around the pot. Their larvae live in soil that stays wet.
• Mealybugs and scale insects: white, cottony tufts or small brown bumps on stems and leaves, often with a sticky residue.

If you find pests, move the plant away from the others straight away. Rinsing the leaves in the shower with lukewarm water removes many of them, and letting the top layer of soil dry between waterings helps against fungus gnats. Yellow sticky traps catch the adult gnats.

Repeat the treatment a few times, as new pests hatch from eggs later. If the problem keeps coming back, ask a plant shop for advice on a suitable treatment.

Bringing a new plant home in winter

Most houseplants come from tropical or subtropical regions and don’t tolerate frost. Even a short trip through freezing weather can damage the leaves, and the damage often shows only a few days later as dark, soft or wilted patches.

If you buy a plant in a shop, ask for it to be wrapped well and take it straight home — don’t leave it in a cold car. If you order online, collect the parcel from the pickup point as soon as you can and unpack it indoors. This matters especially for Christmas favourites such as poinsettias, which are sensitive to cold and draughts.

Give the plant a few days to settle in. Place it in a bright spot without direct heat, check the soil before watering — it may still be moist from the shop — and don’t repot it straight away. It’s normal for a plant to drop a leaf or two after a move. Keep a new plant apart from your others for a while and check it for pests before it joins the group.

Read the warning signs

Plants usually show quite clearly when something is wrong. These are the most common winter signs and their most likely causes:

• Lower leaves turn yellow and the soil stays wet: too much water. Let the soil dry more between waterings.
• Leaf tips turn brown and crispy: dry air or uneven watering.
• Stems grow long and pale, new leaves stay small: too little light.
• Dark, limp or water-soaked patches on leaves near the window: cold damage.
• Leaves drop suddenly after a move: stress from the change. Give the plant time and keep conditions steady.

Change one thing at a time and give the plant a couple of weeks to respond. If a plant wilts even though the soil is wet, check the roots: brown, mushy roots point to root rot. Trim away the damaged roots, repot the plant in fresh soil and water clearly less.

Summary

Houseplant care in winter comes down to a few habits: water less and only when the soil has dried, give your plants as much light as you can, keep them away from both radiators and cold glass, and let them rest without fertiliser. Check them regularly for pests and early warning signs, and remember that every species has its own needs. In spring, when the days get longer, they’ll be ready to grow again.