What to Watch for on Houseplants
By thoroughly inspecting the tops and undersides of plants, the stem, and soil at least once a week through March, you can catch the first signs of insect or fungus problems. Printable PDF Version of this post
If your plants are losing leaves or are turning yellow,
Don’t necessarily blame insects or fungus yet. Drastic humidity swings could be the problem. Bring up the humidity without over-watering by placing trays filled with gravel under your pots. Keep the gravel moist and you create a humid environment for the plant. Investing in a small electric humidifier will benefit not only the health of your plants but your health as well. Only water when the soil is dry to the touch.
Plants still looking blah?
Common pests include aphids, white fly, fungus gnats, powdery mildew, and spider mites. The white fly lays its eggs under the leaf in the shade of the plant. Don’t forget to inspect thoroughly. You’ll find a magnifying glass is a great help. A little reflective foil placed around the base of the plant will help prevent the white fly from laying eggs there. To get rid of them as well as aphids, give your plants a thorough bath in the shower. Spray insecticidal soap or horticultural oil to coat the leaves including the undersides. When plants are dry, return them to their usual location. Inspect in one week and repeat the process two more times, about 7 days apart for a total of 3 applications. This will break the lifecycle between egg stage and adult. Using a yellow sticky card will help monitor the flying insect population and also give some control.
Powdery mildew, the white dusting on plant surfaces, occurs from dramatic swings in moisture and lack of air circulation. Treat with a fungicide spray labeled for powdery mildew. Home remedies include baking soda and water about 1 tablespoon soda per gallon and chamomile tea applied at room temperature at weekly intervals until all signs are gone. Coat undersides of leaves, too. To prevent the mildew, again keep your humidity around the plants stable and don’t pack plants too close together. Light pinching will also allow better air circulation.
Spider mites love the dry air of winter. Yellowing, stippled leaves indicate this parasite may have moved in; wispy web strands between leaves and leaf stems confirm them. Still not sure? Hold a white piece of paper under the plant leaves and tap the stem. Dust specks that land on the paper and move under their own power are mites. Again, give your plants a thorough shower and use insecticidal soap or horticultural oil to coat the leaves and soil surface. And try to increase humidity or mist daily!
Continue to fertilize "weakly". Use half-strength to quarter-strength fertilizer. Plants indoors will start to react to longer days in February and may put out new growth. Pinch this growth back to prevent long “legs” and to make a bushier plant. You’ll want to continue this practice until at least April.