Winter doesn’t have to be that big of a deal for houseplants.
And I say that as someone that lives in a draughty house in the north of England with a tendency to bundle up rather than put the heating on.
My houseplants don’t grow over winter, but I rarely lose them. Their care requirements definitely change in winter, for example I spend more time cleaning them than watering them, but there’s no need to worry about them too much.
Do houseplants go dormant
The answer to this is: some do. Some don’t. Some do a bit. Depends on the conditions and the plant. I wrote an article about it here.
There is a lot of talk about plants going into dormancy over the winter months, and whilst it’s true that the growth rate of plants slows down considerably, that doesn’t mean that your plants can withstand anything and don’t need the occasional drink of water or ray of sunlight.
Your plants aren't hibernating. They're just doing the best they can in suboptimal conditions.
How to care for your plants over winter
Put them in a good spot
Winter is a bit of a catch-22 for houseplants.
They get less light (in the UK the sun goes home pretty sharpish in winter) so they want to be closer to the window, but if they’re close to the window then they might catch a chill.
I'd definitely advise against keeping plants off windowsills over which you're planning to draw your curtains. One of the reasons curtains are effective at keeping out the cold is that they trap cold air between the curtain and the glass.
Not many of your house plants will enjoy that in winter.
I currently only have cacti and succulents on my living room windowsill sill – they are more than happy to tolerate extreme cold (as long as they don’t get wet) because the desert environments they inhabit in the wild get very cold at night.
They don’t care if I close the curtain on them.
Some people even keep succulents outside all winter – as long as they don’t get exposed to frost, they’ll be ok. A greenhouse would be fine for them.
In short, you need to keep your plants away from cold spots and draughts. They won’t like that at all.
You need to maximise the light
Growlights are the obvious choice, but even LED lights can help.
I like these ones, and these ones.
My brightest room is also the coldest, so mine have to go for ok light but also ok temperatures.
I must admit, my plants don’t really pull their weight as home decor items in winter. Instead, I cram them all together in my bedroom window. It’s south-facing so it doesn’t get that cold. Plus they’re new windows so pretty efficient.
As long as the room doesn’t regularly get below 12˚C/53˚F they’ll most likely be fine. They won’t grow, and they look a bit sad, but they shouldn’t die.
Keep humidity balanced
There are various rumours that humidity is low in winter so you need a humidifier.
This isn’t necessarily true – its definitely more humid in winter where I live. I use a dehumidifier.
The other thing we need to bear in mind is that high humidity and low light/warmth are a nightmare. It’s a great way to get root rot and bacterial infections.
If your light is crap and your house is cold, you want humidity to be on the lower end of the spectrum – it’ll be healthier for you and your plants.
What’s the optimal temperature over winter
Optimal? Like, 20 degrees, but that won’t happen without some serious reduction in humidity unless you have a sauna.
House plants don’t much like to go below 17 degrees (excluding desert plants which can go down to minus figures).
As I said, they won’t be in danger until the temperature reaches single digits (that’s celsius – they wouldn’t like single digits in Fahrenheit). That’s what mine have to contend with every year.
If you’re worried about temperature, put all your plants in the smallest room of your house – it’ll be the easiest to heat. If you use grow lights, they should generate enough heat to keep it comfortable – even LED grow lights throw out a decent amount of warmth.
The heat can lower the humidity, but in a small room the water evaporating from the soil should help keep this sufficiently high. It doesn’t need to be very high any way – your plants are unlikely to be growing much.
Watering houseplants over winter
You still need to water all of your plants in winter, but since the plants are growing much more slowly and the sun isn’t around as much to evaporate the water, you will need to water far less often.
A moisture metre will be indispensable in winter (it is to me year-round) because plants are more susceptible to root rot in winter.
I water less in winter – in that I only add a sprinkle of water rather than giving them a thorough watering. It’s not awesome for the roots BUT if all the soil is soaked through it can dramatically reduce the temperature and increase the humidity in a room, which isn’t ideal in winter.
Also, due to central heating, the surface of the soil may dry out pretty quickly, whilst the rest of the soil is bog-like. Don’t rely on your finger (or eyes) to determine if a plant needs watering.
Be sure to use either room temperature or tepid water. Cold water will shock the roots, and we need to keep the roots as happy and healthy as we can. If you’re watering on the fly and don’t have any room temperature water to spare, then boil some up in the kettle to bring it up to room temperature (or even a touch warmer, but never hot).
Some plants, like cacti and succulents, may not need watering at all over winter. Don’t worry about it – they’re literally designed to hold onto water. Just check them regularly and if they need watering, water them. If they don’t, leave them alone.
Pest control in winter
You need to be vigilant about checking for insects and diseases in winter – the plant will be in a weakened state and will succumb to infestation and infection much quicker.
I only check if my plants need watering every couple of weeks in winter so every other week I do a lot of pest checking and leaf-cleaning.
I would recommend staying on top of dusting your plants so that any potential pest threats can be sorted out early. A quick dust and polish with neem oil will help to keep bugs at bay without resorting to any harsh insecticides.
If your plants are already attracting a lot of bugs such as fungus gnats, then try to suppress them before winter. Add a layer of pebbles or sand to the top of your pots so that they can’t lay their eggs and any larvae can’t get out. This can also provide a layer to help keep the plants warm.
Fertilising plants in winter
I don’t fertilise my plants in winter. It’s too cold and dark for them to grow much, so fertilising them would just stress them out unnecessarily.
Would it do them any real harm? Unlikely, but it’s a waste of time and fertiliser.
HOWEVER
If you live in a modern, energy-efficient home and you have a lot of light and the heating on all the time, then your plants may not even notice that it’s winter.
There is no ‘don’t fertilise plants in winter’ rule. The rule is: if your plant is growing, it will need feeding to reach its full potential. Even in winter.
Don’t neglect your plants in winter
If your plants aren’t growing and they don’t need watering then it can be tempting to just ignore them all season.
Don’t do that. We need a weekly pest check, minimum.
I like to devote most of my plant care time towards cleaning the leaves. Not only does it reduce the chance of getting pests (pests love dust, especially spider mites) but it ensures that the leaf surface is clear to absorb whatever light there is available.
I use one of those makeup erasing cloths, but a lot of people swear by dusting mitts and can see their point. It does seem like the easest way to clean leaves, especially plants with a lot of tiny leaves.
Final thoughts
When it comes to winter houseplant care, lower your expectations. I don’t want growth, I don’t want deterioration. I want the status quo, from October to March.
There’s nothing you can’t do.
If you need to repot, repot. If you need to take cuttings, go ahead. I propagated my Phildoendron brasil in February and it worked fine.
But also...expect that when you make any changes to plants when they're dormant, things like rooting and recovering from shock can take longer, and you may need to be more vigilant about pests.
I’ve honestly never had an issue repotting in winter, but I’m careful not to disturb the roots, and not to go up too big a pot size.
