Last week, I wrote about light and temperature requirements for house plants during the winter months.

Next in importance is humidity. In the winter, our homes and offices are much drier than at other times of the year because of heating. The humidity can easily drop below the tolerance range of plants unless you have a house full of cacti. Dried up leaf margins are a good sign that your plants are suffering from low humidity. A furnace humidifier can help but humidifiers can push the humidity to levels where you end up with condensation problems that lead to mould.

Put your house plants together in one area rather than have them scattered all over the house. In that way, the plants create their own micro-climate. To increase the humidity just around the plants even more, get some large plant saucers, fill them with pebbles, set the plants on the pebbles and keep the saucers filled with water so the plants don’t sit in water but get the benefit of the water evaporating around them. Be particularly careful with overpots. They look nice but fill with water without you realizing it. I have killed more than one plant that way.

Misting of plants is often recommended but in reality, you would have to spend most of your day with a mister in your hands to do any good; and too much misting will leave an unsightly residue on the plant leaves as the water evaporates. Taking your plants into the shower occasionally will help to wash ordinary household dust off your plants, but don’t do that with hairy-leaved plants such as African violets!

Fertilizer really can “kill your plants with kindness”. Because your plants are growing much slower due to reduced day length, their fertilizer needs are much reduced. If you keep fertilizing them the way you do during the summer fertilizer will build up to harmful levels very quickly. Observe your plants. As the days lengthen in spring, you will notice that they are ready to start growing again. That’s the time to go back to a regular fertilizer routine.

As for watering, more house plants are killed by over-watering than any other way. Keep your plants moist but not wet. That requires a soil mix containing enough humus in the form of peat moss or leaf mould to hold water but with enough coarse material such as coarse sand or, better still, perlite, to provide drainage.

Apply water to the point that some water drains out the bottom of the pot into the plant saucers. After a few minutes, empty the saucers, then leave the plants alone until the top of the soil feels dry to the touch, which may be in two or three days or two or three weeks, depending on the type of plant and the conditions in your house. And NEVER water your plants with water that has been treated by a water softener! Water softeners replace the calcium and magnesium occurring naturally in tap water with sodium, which is deadly to plants (and not particularly good for humans, either, but that’s a different story).