Before bringing them back inside, inspect houseplants carefully for hitchhiking pests they may have picked up.

Temperatures are dipping into the low 50s to upper 40s nearly every night now and the weatherman has uttered the F word. “Expect scattered frost in the cold mountain hollows,” he said this week. Yes, summer is winding down and the outdoor vacation for houseplants is over!

Before I bring my begonias, orchids, caladiums, and other tropical plants back inside for the winter, they need a thorough inspection. I’m looking for unwelcome pests that can — and will — proliferate and spread inside the house. During the winter, houseplants don’t get as much sunshine, airflow or humidity as they do outside, so they grow less vigorously, making them more susceptible to pests and disease. And the natural predators that may have kept some pests under control during the summer aren’t present when the plants come inside.

The houseplant hitchhikers I commonly find are slugs, snails and earwigs. These usually hide under the leaves, and in nooks and crannies, just under the surface of the soil, or at the bottom of the root ball near the pot’s drainage holes. I look for slime trails, brush all plant debris out of the pot and scrape the soil surface lightly to uncover any hidden critters. If the plant isn’t too large, I also tip it gently out its pot to check the root ball. Sometimes earthworms sneak into potted plants and I remove these, too. I don’t know why, but I’ve found over the years that potted plants don’t seem to grow as well with earthworms. Could be that their tunneling is too disruptive to the roots in such a small volume of soil.

Aphids, spider mites, mealybugs, thrips and scale insects also frequent summering houseplants. It’s often easier to see their damage than the insects themselves. Here’s what I look for:

  • Deformed tender new growth, flowers, and flower buds
  • Ragged leaf edges and holes
  • Very fine spider webs under leaves and between stems
  • O-shaped bumps (scale insects) on and under leaves and stems
  • Unusually silvery or stippled foliage
  • Sticky residue on leaves, pots, or the deck floor

If I find pests, I treat the plants outdoors before bringing them in. I use either Bon-Neem Insecticidal Soap or Insect Control Spray. Sometimes they need a repeat treatment, so I try to plan ahead and get everything cleaned up before the first frost. After they come inside, I keep plants spaced so that pests can’t easily crawl from one plant to the next and I watch them carefully for the first month. Catching the bugs before they get out of hand makes my winter, and my plants’, much more pleasant!

For More Information

Ann Whitman,

Green Goods Supervisor, Gardener’s Supply