Grow lights for indoor plants in winter (UK)

November 6, 2026

Cosy winter windowsill plants under a slim light, with a knitted mug beside the pots

UK winters are hard on indoor plants. Days are short, the sun sits low, and central heating dries the air. A plant that looked lush in September can stretch, yellow or stall by January in the same spot. Grow lights for indoor plants (plain white full-spectrum plant lights) are a practical winter tool for UK homes, not a specialist hobby. Used on a timer, they top up daylight so herbs, houseplants and early seedlings stay sturdy until spring.

The RHS recommends artificial lighting when natural light indoors is too weak, especially in winter. Dobbies frames grow lights as a way to keep indoor plants healthy through dark months and to strengthen young plants. Which? found plants under lights grew more strongly than windowsill comparisons in winter tests.

Why winter breaks the usual routine

Day length collapses; many rooms never see strong sun
People keep summer watering habits while plants drink less
Radiators create dry air and scorched nearby leaves
Curtains trap pots against cold glass at night

If leaves are yellowing or plants look generally poorly, work through Why are my indoor plants dying? as well as adding light. Light alone will not fix soggy roots.

What to set up for winter

White full-spectrum LEDs for any room you live in (white vs purple).
A timer for a steady day length (hours guide).
Sensible distance above the leaves (distance guide).
Less frequent watering, checking compost with a finger.
Humidity help for tropical foliage: pebble trays, grouping, or Climate Control.

Hours in the dark months

As a home starting point in winter:

Houseplants topping up weak daylight: about 10 to 14 hours
Herbs and salad leaves indoors: about 12 to 14 hours
Seedlings with little daylight: around 16 hours

Give plants a dark night. Do not leave lights on 24 hours.

Where winter lights earn their keep

North-facing living rooms and basement flats
Kitchens where herbs lose flavour and colour on the sill
Hallway shelves that looked fine in summer
Early seed sowing for spring (February and March trays)

A single bar from Plant Lighting can save one favourite plant. A lit stand keeps a whole collection going without fighting over the only sunny window. See Plant stand with lights: which shelf?.

Soft product paths for winter

Compact kitchen: Spider Farmer slim herb stand or Mars Hydro small 54W
Wider houseplant wall: Mars Hydro vertical garden 150W
Salad and microgreens through winter: Spider Farmer microgreens shelf

A simple November to February routine

Weekly: wipe dust off leaves and light bars so winter gloom is not made worse. Twice weekly: feel compost; water only when the top is dry. Monthly: turn pots, pinch herbs, and check for spider mites (worse in dry heated air). Seasonally: in late autumn, move your hungriest plants onto the lit stand before they stretch. In April or May, trial shorter hours if south-facing sills brighten up.

Pair light with humidity help for ferns, calatheas and other soft tropical foliage. Dry air and low light often arrive together in UK winters.

Electricity in winter

Lights may run more hours than in summer, but modern LEDs stay frugal. Which? notes grow lights can cost less than 2p an hour. Example: 54W for 14 hours at 25p/kWh ≈ 19p a day. Check your own tariff.

FAQ

Should I leave plant lights on all winter?

Use them through the dark months on a timer, then ease off in late spring if your windows become bright enough again. Some dark rooms need lights year round.

Can winter plant lights replace a greenhouse?

For leafy crops, herbs, microgreens and many houseplants, a lit shelf is enough indoors. Full summer tomatoes still prefer a brighter greenhouse or outdoor spot later on.

My plant dropped leaves in October. Is it too late?

Not if the crown is firm and some green remains. Correct watering, improve humidity, add light, and wait for spring growth. Old dropped leaves will not return.