Why Winter Asks More of Us Than We Think

By the time the last of the leaves have come down, most of our houseplants have already slipped into a slower rhythm. Light levels in a British winter can fall to a fraction of what they were in June, growth all but stops, and compost that dried out in a day or two in July can now stay damp for a fortnight. Add central heating, draughty sash windows and a few sharp frosts, and it is easy to see why January and February claim more tender plants than any other months of the year.

The good news is that very little of this requires heroics. A handful of small adjustments — less water, more humidity, a kinder spot away from cold air — will carry your ferns, philodendrons and scented-leaf pelargoniums through to March in good heart.

Water Less, But Water Well

Overwatering is by far the most common way to lose a houseplant in winter. With light so scarce, plants use very little water, and compost that stays wet starves the roots of oxygen and invites rot. Before you reach for the watering can, push a finger two or three centimetres into the compost. If it feels at all moist, walk away and check again in a few days.

• Let the top layer dry out between waterings for most foliage plants; succulents and cacti may need nothing at all from November to February.
• Water thoroughly but less often, letting the excess drain away completely. Never leave a plant sitting in a full saucer.
• Use tepid water, ideally left to stand for an hour so the chill comes off it. Cold tap water gives tropical roots a shock.
• Ferns, which resent both drought and sodden roots, prefer a consistently damp-but-not-wet compost. Little and often suits them better than a weekly drench.
• If a plant is in a cool room below about 12°C, cut watering right back. Cold and wet together is the killer combination.

Humidity Is the Fern's Best Friend

Central heating wrings the moisture out of the air, and nothing sulks about it quite like a fern. Crisp brown tips on a Boston fern, or a maidenhair shedding leaflets at the slightest provocation, are usually a plea for humidity rather than a sign of poor watering. Aim for a moist atmosphere around the leaves without making the compost wetter.

• Group plants together so they share a pocket of humid air.
• Stand pots on a tray of pebbles with water kept just below the base, so roots never sit in it.
• Mist ferns in the morning, never in the evening, so leaves dry before the temperature drops.
• A bathroom with good light suits ferns, orchids and spider plants beautifully, provided there is a window.
• Kitchens and utility rooms often hold humidity well; a small electric humidifier in a sitting room is no indulgence if you keep several ferns.

Mind the Draughts and the Radiators

Position matters as much as care. Tropical plants dislike sudden swings in temperature and hate cold, moving air even more. A windowsill that is lovely in May can be a cruel spot in December, particularly with single glazing and a gap under the frame.

• Move tender plants a foot or so inwards from the glass during the coldest weeks, or line the sill with a piece of card as a barrier.
• Keep foliage clear of radiators and wood-burning stoves; hot, dry air scorches leaves and dries compost unevenly.
• Avoid doorways, hallways and any spot where people pass and create a draught.
• Most houseplants are happiest between roughly 15°C and 24°C by day, with slightly cooler nights. Ferns and citrus prefer the lower end; most tropicals will not thank you for anything below 13°C.

Light, Leaves and a Light Feed

Move plants to the brightest place you can offer, even if that means shuffling the whole collection onto one south or west-facing windowsill. Turn each pot a quarter turn every week so growth stays even rather than leaning towards the light. Dusty leaves cannot photosynthesise well, so wipe them gently with a soft damp cloth; a shiny-leafed rubber plant or hoya will visibly perk up afterwards.

Feeding should be all but paused. Most plants are not growing and cannot use the nutrients, which simply build up in the compost. Give a half-strength feed no more than once a month to plants still pushing out new leaves, and nothing at all to anything resting. Resist repotting until spring, too. Roots disturbed in the cold are slow to recover, and a pot-bound plant will happily wait a few more weeks.

A Quiet Watch for Pests

Warm, dry indoor air is a gift to spider mites, mealybugs and fungus gnats. Check the undersides of leaves and the joints where stems meet whenever you water, and deal with anything you find promptly with a damp cloth or a dilute soap spray. Yellow sticky traps see off fungus gnats, whose larvae thrive in permanently wet compost. If a plant looks beyond saving, move it away from the others rather than letting the problem spread.

Finally, bring a little cottage comfort to the task. A vintage terracotta pot, a woven basket and a cluster of ferns on a stand will do more for a winter windowsill than any gadget. Keep the compost on the dry side, the air around the leaves soft and damp, and the draughts at bay — then simply wait. The light is already lengthening, and your plants will thank you for it come March.