Houseplants and heating

It's time to audit and move your houseplants 

Almost New Year's Eve, and it's ten degrees Celsius outside. It's been a warm year, but the time is definitely coming for even the hardiest of us to switch the heating on. Remember, though, what's comfortable for you isn't always comfortable for your indoor plants!

If you're anything like me, you're guilty of 'houseplant blindness'. You bought a new green friend months ago, placed it on the windowsill, and you're so used to it being there it never occurs to you that its living conditions have now changed.

But they have. 

That warm spot may now be uncomfortably drafty. The perfect windowsill may be blasted with hot air from your heating system. The results show in drooping foliage, crispy leaves and failure to thrive. I'm here to tell you to move your houseplants!

Do an audit

Look at each plant and check its preferences before you start. This is a good opportunity to check what your houseplants are! If you have any that are unlabelled or that you aren't sure about, apps like Google Lens (free) or RHS Grow (paid) are handy for identifying them. For each, you want to know:

• What light levels does it like (sunny, shade, part-shade)?
• How hardy is it?
• Does it go dormant? When? 

Cool your cacti

It's a good idea to move all your cacti into cooler rooms as soon as winter starts. They generally go dormant during the winter months, and should be kept somewhere dry, reasonably bright and away from heat. 

Mine all go into the downstairs loo at this time of year. It's a bit of an icebox compared to other rooms in the house, but doesn't drop below about 10 degrees, and it's free from draughts.

Obviously, don't put your cacti anywhere too cold. They don't generally like to be outside - or in the fridge!

Don't toast or ice them

In the UK, it's very common for radiators to sit directly below a windowsill. And a windowsill is often the best place for many plants. But in winter, the rising hot air can dry out your plant, damaging leaves and causing stress. 

Cold air can also be trapped between curtains and windows. When you close a thick set of drapes, you might be keeping your room nice and warm, but unwittingly boxing your poor plants into a chilly chamber! 

Indoor plants generally like consistent temperatures. If they're seeing extremes of heat or cold, you might see wilting, yellowing leaves or even crispy edges.

Many houseplants are tough enough to be unharmed by a cold night on the sill. A ZZ plant (Zameoculcas zamiifolia) or a Dracaena, for example, will be fine. But if you've got a spider plant (Chlorophytum), croton (Codiaeum variegatum), calathea or nerve plant (Fittonia albivenis), keep them well away from both cold draughts and blasts of warm air. 

If you have a calathea, it will serve as a 'mine canary' for your other plants. They're incredibly sensitive to all sorts of things, including temperature, and if yours starts looking unhappy in winter it's a good sign that there are temperature fluctuations in the room.

Provide enough light

Shorter daylight hours means your plants are getting less light during the winter. This shouldn't be a problem for most, but if they're in an already-shady spot, the low winter sun could be depriving them of rays that were keeping them alive in summer. 

Take the time to look at your plants a few times throughout the day, especially any in north-facing rooms. Do they get enough light from morning to evening? If any seem to be struggling, try moving them to a brighter spot. 

Remember, the sun still comes out in winter, so you don't want to scorch a plant that prefers indirect light - but you might want to move some from far corners closer to windows. 

You can also use artificial lights to give your plants a boost in winter. Although you can't use just any old lightbulb, you also don't need a professional growlight. Cheap growlights with T5 fluorescent tubes are available at many garden centres and online outlets for under £20 and will do the job. Alternatively, I use an old fishtank with a T5 aquarium bulb as a terrarium for my carnivorous plants, and they're quite happy year-round. 

Stop feeding and water less... mostly

Most houseplants (not all) go dormant in winter. That means you should stop feeding them, water them less, and let them rest. 

This is an Albuca spiralis, delightfully named 'Frizzle Sizzle'. The first year I had it, I treated it like my other houseplants - more water and feed in summer, less in winter. I couldn't work out why the curly leaves kept straightening, bolting, yellowing and generally showing signs of stress - until I realised it was supposed to go dormant in summer and wake up in winter! 

Now I feed and water it from around November to April, let it dry out and go unfed during the warmer months, and it's as happy as Larry.

If you've got a plant that isn't performing as expected, check you've got it on the right yearly cycle. A number of houseplants, including succulents like Monilaria and some Haworthias, are summer-dormant.