We have entered our low-light phase of the year — that means lots more time to curl up in front of the fire to read a good book. We will enjoy that, but our houseplants will not be as contented.
My portable houseplants returned this week from summer camp. Well not really, they just spent the summer in the fresh air on the north side of my house. They grew in natural light, and their leaves were regularly washed with the sprinkler. The venerable houseplants — mostly over 30 years old — are too big to move outside, but I moved them to a brighter window for the summer.
All the houseplants were fertilized once a month. The best time to fertilize is when they are growing rapidly in great conditions. The plants can utilize the fertilizer, and there is not accumulation of excess salts. More importantly, when the plant is growing in good conditions, the plant’s growth is vigorous and healthy.
In low-light conditions, growth forced by fertilizer is usually wimpy and succulent — just what the sucking insects ordered!
If your plants did not summer outside, a sane fertilizing schedule follows the seasons. For the spring equinox, provide fertilizer at one-quarter strength (the water will barely be blue). For the summer solstice, fertilize at half-strength, and for the autumnal equinox, fertilize at one-quarter strength. Do not fertilize at the winter solstice since the inside light is barely strong enough to support plant growth. Of course, if you use grow light, you can fertilize at half-strength for all the seasons.
This is the time of year to prune back unruly houseplants to get them ready to be admired by holiday guests. Get rid of dead leaves or long, stringy growth. Then give your plants a shower, either in the bathroom or by placing plastic on the floor and gently squirting the tips of the leaves of large plants. We live in a windy, and often smoky, area, and you will be surprised how much dust is washed off the leaves of the plants.
Plants need clean leaves for two reasons. First, light is essential for photosynthesis. A dirty surface reduces the amount of light that reaches the leaves. More importantly, dust is a hiding place for insects, especially red spider mites that love hiding in the dust that provides anchors for their minute webs.
This is also the season for tough love. If one of your plants has been languishing for several seasons and has never regained its vigor, toss the plant out. I know this is hard. Twenty years ago, I planted a coffee bean and nourished it until it became a small coffee tree. It ended up becoming a magnet for scale insects which can rapidly infect every nearby plant, so I kissed it goodbye at the compost bin. It was difficult, but if I can do it, you can do it.
If you bathe your houseplants, fertilize moderately and eliminate the weakened plants that will become susceptible to insect infestations, you will have more time to sit back and read.
A WSU Master Gardeners of Chelan County column appears weekly in the At Home section. Bonnie Orr is one of four columnists featured.