Preparing Houseplants for Autumn and Winter

Autumn is a reset, not a shutdown

By the time the clocks go back, your houseplants have already noticed. Daylight is shorter, the sun sits lower in the sky, and even a bright room receives a fraction of the light it enjoyed in June. Growth slows, some plants stop altogether, and a few — succulents and cacti in particular — begin a genuine rest period. This is entirely normal. It only becomes a problem when we carry on watering and feeding as though it were still midsummer. The most common cause of houseplant deaths between October and March is kindness: too much water, too much fertiliser, too little light. Adjust those three things and most plants will sail through to spring.

Ease off the watering can

Watering is where the biggest change is needed. As growth slows, roots take up far less moisture, and compost that dried out in four days in July may now stay damp for a fortnight. Aim to water less often rather than in smaller amounts: a thorough soak that drains freely, followed by a longer gap, suits almost every plant better than a daily drizzle.

• Check before you pour. Push a finger two or three centimetres into the compost. If it feels cool and damp, wait.
• Let the top few centimetres dry out for most foliage plants. Snake plants, ZZ plants, pothos and succulents can go drier still.
• Empty saucers and outer pots half an hour after watering. Standing water is a fast route to root rot.
• Use tepid water. Cold tap water chills tropical roots.
• Water in the morning where you can, so splashes on leaves dry before the cooler night.

A plant in a cool, dim spare room may need water only once every three or four weeks, while one on a bright kitchen windowsill with the heating on will drink far more. Judge each plant individually rather than by the calendar.

Put the feed away

Feeding follows the same logic as watering. Fertiliser encourages new growth, and new growth needs light to support it. Push a plant to grow in November and you will get pale, spindly stems that struggle for weeks. Most houseplants can be left unfed from late autumn until early spring.

If a plant is still actively growing under a bright window or a grow light, a weak feed once every six to eight weeks is plenty — roughly half the strength recommended on the bottle. Cacti and succulents in their resting period should be given nothing at all. Resist the urge to give everything a boost before winter; the boost they need is rest.

Move plants towards the light

Light is the resource in shortest supply, so make the most of every hour. A spot that felt comfortably bright in July may now be genuinely dim, and a plant sitting a metre back from a window can receive less than half the light available on the sill itself. Autumn is the ideal time to shuffle pots closer to the glass — ideally within half a metre of a window that gets decent daylight.

• Rotate pots a quarter turn each week so growth stays even rather than leaning towards the pane.
• Clean windows inside and out; grime and condensation can cut light noticeably.
• Wipe dusty leaves with a soft damp cloth. Clean leaves photosynthesise more efficiently, and it gives you a chance to spot pests.
• In very cold snaps, move plants off the windowsill at night or draw curtains leaving a gap. Tender leaves pressed against icy glass can scorch.

Mind the warmth, draughts and dry air

Most tropical houseplants are happiest between about 15°C and 24°C, and they dislike sharp swings far more than a steady, slightly cool room. Radiators, open fires and draughty doorways all cause stress: the first bakes leaves and dries the air, the second chills roots.

Central heating also strips humidity, which is why spider mites and brown leaf tips appear in January. Group plants together so they share a little moisture, stand pots on a tray of pebbles with water kept below the pebble line, and keep plants a good arm's length from radiators. Misting helps for a moment but does little for a whole day; a pebble tray or a small humidifier is far more reliable.

Give everything a quick once-over

Before the heating season settles in, spend ten minutes with each plant. Remove yellowing or dead leaves so they cannot harbour mould, and trim soggy stems back to firm tissue. Check the undersides of leaves and the joints where stems meet for webbing, sticky residue or tiny specks. Pests build up quietly in autumn, and catching them now is far easier than in February. A weak insecticidal soap, applied to a well-watered plant, will deal with most early infestations.

Finally, hold off on repotting until spring. Roots are resting, and fresh compost around them can stay wet too long in low light; a top-dressing of fresh compost is gentler. Do these few small things and your plants will come through winter in good shape, ready to grow away strongly when the light returns.