I had thought this was a well-settled practice: we don’t fertilize house plants in winter months (whatever those months are for you).
But this year, I have begun to see all sorts of social media posts, accompanied by photos, of plants with new leaves and the advice to keep fertilizing through winter.
What’s going on?
To be honest, I think that people are seeing leaves and believing that plants need fertilizer in winter. Do they?
They surely do not in my house. This is not to say that none of my plants ever make new leaves in winter. Some occasionally do. The ones most likely to put on new growth in the winter are my ancient ficus elastica ( but neither of my two newer ones grow–perhaps because they are variegated); a saxifrage; a couple of rex begonias, an osmanthus–very few plants.
The photo above–the bird of paradise with what looks like a new leaf about to unfurl–that leaf has looked like that since I acquired the plant in December. I even did the unthinkable and potted it in my own container (because the nursery pot was just unacceptable and nearly broken–it really couldn’t live in that pot until about now, which is what I normally would have let it do) and that leaf stayed tightly closed. No growth for me in December, January, February or even early March. This is why we call it the frozen north–and don’t waste fertilizer.
In fact, I can more easily number the plants that lose more leaves than not: croton, calatheas, anglaeonemas, citrus, abutilon, even my pothos will lose leaves and not gain any until a month or two from now.
So for me to actually fertilize any of this would be absurd. I know my plants.
But for those who do see growth, more power to them. They must live in a warmer home than mine (not hard to do) and perhaps have different latitude.
I can’t pass judgment on them for fertilizing–but I do think they ought not presume that everyone has plants growing in the winter and should be doing the same thing.
Gardendaze 
There are a few factors to consider. Most houseplants are tropical plants that really do not know what to do through winter. Even if the home constantly stays warm and illuminated, they know that days are shorter. Some houseplants are more responsive to photoperiod than others are, so will grow slower. Some take that time to expand their root systems instead. Others may be pleased to grow as long as they are warm. Because I fertilize only palms and blooming houseplants, such as orchids and African violets, I do not give much thought to fertilizing other houseplants. Palms in my home get fertilize only once or twice annually, and actually get their fertilizer early in winter to compensate for the cooler temperatures in my home. (I do not heat my home much.) The micronutrients that they crave are less soluble while the medium is cool. Orchids get their fertilizer shortly afterward as they begin to expand their bloom. However, in the garden, tropical plants get no fertilizer after the middle of summer because I want them to be more resilient to chill or even mild frost. Fertilizer stimulates new growth for plants that are not accustomed to seasons, and such new growth is sensitive to chill. Even if it does not get damaged by frost, it get pale and stunted. I have wondered if the justification for not fertilizing houseplants through winter is related to the justification for not fertilizing tropical or subtropical plants in the garden.
You’re not kidding about most plants not knowing what to do in the winter–at least here in the frozen north!! Even now, as we are definitely getting some warmer sun, it’s as if they are slowly beginning to emerge from dormancy, for lack of a better word. The plants that you would be accustomed to seeing in the garden–like my olive tree–is starting to put out some new shoots–but things like my lemon tree are still shivering and dropping leaves. So the idea of fertilizing something like that just makes me laugh.
Anyway, it’s just a counter thought to those plant people all over instagram with their videos of leaves unfurling. Sheesh!
Karla