Winter is often hard on houseplants, but if you know how to treat them right, you can keep them as healthy and happy as they were in summer!
Light is scarce in winter and this really hurts tropical plants. After all, in their native lands, they’re use to days that are just as bright and long in winter as in summer. In homes outside of the tropics, though, they have to put up with short days and much weaker solar rays, a condition made even worse by weeks of cloudy weather. So give them all the light you can by placing them near their major source of light: the window in the room where you grow them. Don’t worry about them burning from being too near the window: winter sun is weak and won’t burn anything! By the end of February, though, when days are longer and the sun more intense, move the plants back from the window to their usual position.
With their growth slowed down by poor light, plants use less water in winter than in the summer. If constantly allowed to soak in water, their roots will be unable to breathe and will soon rot. And the whole plant often follows! Make sure you only water your plants when they really need it. If in doubt, sink the first digit of your finger into the potting mix. If the mix still feels a bit wet, wait an extra day or two before you water.
Slow growth also means plants need less fertilizer in winter than in summer. Cut back the fertilizer rate to one quarter of the usually recommended concentration. And for plants that go entirely dormant in winter, like cactus and succulents, stop fertilizing completely. When new growth appears in late February, it’s a sign there is now enough sun for them to grow normally and you should therefore increase their feedings to the normal rate.
Most houseplants prefer an annual repotting. Not only does this give their roots more room to grow, but also, over time, harmful mineral salts slowly build up in the mix and render it toxic. However, some houseplants, like oleanders (Nerium oleander) and hibiscus (Hibiscus rosa-sinensis), actually flower better when they’re a bit underpotted. Rather than repotting them each year, it may be wiser to simply replace the top layer of potting mix. Since toxic salts tend to accumulate only in the upper layer of mix, this solves the problem quite nicely. Just scrape off the upper 1/2 inch (1 cm) or so using a kitchen fork and replace it with a layer of fresh mix such as PRO-MIX® Ultimate Potting Mix, then water well. By “top- dressing” annually in this manner, you can leave many plants in the same pot for 3, 4, 5 or even 6 years!
Just follow the above advice and your houseplants will never have been happier!