Houseplant care in winter: how to keep plants healthy when the heating is on

The heating is back on and the days are getting shorter. Your plants notice straight away: yellow leaves, brown tips, droopy stems or a sudden outbreak of thrips or spider mites. In most cases that isn’t caused by too little care, but by the wrong kind of care. In winter a houseplant needs something very different than in summer. In this article you’ll learn how to handle houseplant care in winter, and how a few simple measurements take the guesswork out of it.

Quick answer: what do houseplants need in winter?

• Less water: only water when the top 2–3 cm of soil is dry. For most plants that’s once every 1–3 weeks.
• More light: move plants closer to the window or use a grow light for 8–12 hours a day.
• Higher humidity: aim for 40–60% relative humidity. With the heating on, indoor air often drops to 25–35%.
• No fertiliser: stop feeding from November to February (except for plants actively growing under a grow light).
• Stable temperature: 16–22 °C, away from cold draughts and not directly above a radiator.

Mistake 1: overwatering

Overwatering is the number one killer of houseplants in winter. With low light levels a plant barely grows and loses far less water. If you keep watering as you did in summer, the pot stays wet, the roots run out of oxygen and root rot sets in. The tricky part: a plant with root rot also shows limp, yellow leaves, so you think it’s thirsty.

So don’t water on fixed days; water based on what’s happening in the pot. The finger test works for small pots, but in larger pots the top layer is often dry while the bottom is still wet. A digital moisture meter measures moisture at root level, so you know exactly whether watering is needed. Prefer something without batteries? A Seramis watering indicator stays in the pot and changes colour when it’s time to water.

Tip: use room-temperature water and water in the morning. After fifteen minutes, empty any excess water from the saucer or cachepot.

Mistake 2: dry air from the heating

Brown leaf tips, curling leaves and suddenly spider mites or thrips? The air is probably too dry. Tropical plants such as calathea, monstera, alocasia and ferns come from environments with 60–80% humidity. In a heated home in winter that’s often down to 30%.

How to raise humidity:

• Group plants together: they raise the humidity around each other.
• Place the pot on a tray of clay pebbles with a little water (the pot itself shouldn’t sit in the water).
• Use a humidifier for sensitive species.
• Keep plants away from directly above or next to radiators.

Misting only helps for a few minutes, so it’s not a real fix. Measuring works better: with a WiFi temperature and humidity sensor you can see in the app how humid and warm it is around your plants, all night long. You can even set an alert for when humidity drops below 40%.

Mistake 3: not enough light

In December a plant on a north-facing window can get less than 500 lux, while many houseplants need at least 1,000–2,000 lux to stay healthy. Long, thin stems, small new leaves and plants leaning towards the window are clear signs of light deficiency.

• Move plants closer to the window in winter (but don’t let leaves touch the cold glass).
• Clean your windows: it makes more difference than you’d think.
• Give the pot a quarter turn every week for even growth.
• Supplement with a grow light for 8–12 hours a day.

Not sure if a spot is bright enough? Check it with a digital light meter; the human eye is terrible at judging light intensity. If it’s too dark, a grow light with an E27 fitting is a simple, affordable fix: just screw it into an existing lamp. Want to know more about choosing the right lamp? Read our article grow lights for plants: which one to choose?

Mistake 4: still fertilising

A plant that hardly grows hardly uses any nutrients. If you keep feeding, salts build up in the potting soil. You’ll see a white crust on the soil or scorched leaf edges. Stop feeding from roughly November to February and start again once the days lengthen in March. Not sure whether there are enough (or too many) nutrients in the pot? A 4-in-1 Bluetooth plant monitor measures moisture, light, temperature and nutrient level, and shows in the app whether your plant is in the right zone.

Mistake 5: cold and draughts

Most houseplants are perfectly happy between 16 and 22 °C. Problems arise with big swings: a windowsill that cools below 12 °C at night, an open door letting in cold air, or a plant baking above the radiator during the day. Watch out especially for plants between the curtain and the window: it can get much colder there at night than in the room.

Winter checklist for your houseplants

1. Check moisture at root level before every watering.
2. Measure humidity: below 40%? Take action.
3. Measure the light where your plant stands and add a grow light if it’s below 1,000 lux.
4. Stop fertilising until March.
5. Keep plants away from radiators, cold windows and draughts.
6. Check the undersides of leaves every two weeks for spider mites, thrips and mealybugs.

Frequently asked questions

How often should you water houseplants in winter?

Usually once every 1–3 weeks, depending on the plant, the pot size and the temperature in your home. Succulents and cacti sometimes need water only once a month in winter. Only water when the soil feels dry at root level or your moisture meter reads “dry”.

Why do my houseplants get brown tips in winter?

Brown leaf tips are usually caused by dry air from the heating, sometimes by excess fertiliser or hard tap water. Measure the humidity and raise it to 40–60%.

Can you repot houseplants in winter?

Better not. A resting plant recovers slowly from repotting. Wait until spring, unless there’s acute root rot.

How many hours a day should a grow light be on in winter?

For most houseplants 8–12 hours a day is enough. Use a timer so the plant gets the same rhythm every day.

In short

In winter, houseplants need less water, more light, more humid air and no fertiliser. Measuring instead of guessing prevents the most common mistakes. Browse our measuring instruments and get through winter together with your plants. 🌿