For those fortunate who dwell in the tropics, horticulture is a year-round outdoor affair. The rest of the gardening fraternity is not so blessed. When winter winds wail, it is time to move inside to indoor pursuits.
Like us, shorter and gloomier days affect plants as does the dry air caused by necessary heating. The reduced light means an equal drop in growth activity. This results in a drop in moisture requirements and, except for flowering specimens, a lack of need for nutrients. In short, forget the fertilizer. Plants in smaller containers, 15-centimtres (six inches) or less will still require the occasional watering, if at greater intervals. Those in containers 25cm (10-inches) or larger may go for weeks, even months, without a shot of H2O. When it is applied, it must be at room temperature to avoid root rot.
The air in the average northern house in midwinter is drier than that in the middle of the Sahara. And nothing grows there. Not even cacti. Contrary to popular belief, spritzing plants does not raise the humidity. A humidifier is the only real answer, although a daily spray will remove dust from foliage and so encourage photosynthesis. This also discourages
numero uno of overwintering indoor plants, the dread spider mite.
Sooner or later, every indoor gardener notices fine webs covering some plants, which taken on a dusty, dull appearance. Or the lower foliage and floor below is smeared with sooty spots. The former is spider mite, the latter the excrement (ugh!) of aphid, whitefly or scale insects. Spray with insecticidal soap every five days for at least three weeks.
