3 hours Ago By Don Kinzler
Did you hear about the guy who read a book about glue? He couldn’t put it down. Gardeners also love to read, and researching how to bring plants indoors in the fall is a popular topic. It’s popular because unless certain precautions are taken, a whole zoo of insects can hitchhike indoors, lurking among the leaves and stems.
Houseplant growers often move their plants outdoors to a sheltered spot during summer, where the plants thrive and add vibrant new growth during summer’s long days and fresh air, before being brought back indoors before autumn night temperatures drop below about 50 degrees Fahrenheit. ADVERTISEMENT Some outdoor flowering container plants can also be taken indoors and grown as winter plants before returning them outdoors the following spring. Included are mandevilla, begonias, coleus, geraniums, thunbergia and others.
When our houseplants and other container plants are outdoors, nature can keep insects in check, either from natural predators or weather that doesn’t favor a population explosion. But when plants are brought indoors to a pleasant atmosphere free from the wiles of weather and lack of natural enemies, insects can flourish out of control. We can almost be assured that insects, or their eggs, will tag along when plants are brought inside.
Even if a plant isn’t visibly crawling with creatures, eggs can be present, or a few unseen insects might be hiding, waiting to get indoors before multiplying in a population boom that would make a rabbit envious. To avoid turning your plants into an insect hatchery and dealing with the situation when leaves are crawling with activity, it’s easier to be proactive, reducing the likelihood of trouble before insects hitch a ride indoors. When it’s time to bring plants indoors, the first proactive step involves washing the plant to dislodge insects, visible or hidden.
Upper and lower sides of leaves can be washed with a gentle stream of water. Or the leaves and stems can be submerged in a tub of water and held under for a few seconds, swishing the plant to remove insects. When giving plants their bath or shower before allowing them indoors, insecticidal soap or other plant-friendly soaps can be used.
Avoid dishwashing detergents though, because their grease-fighting compounds can injure a leaf’s natural waxy protective coating. While the plants are still outdoors, houseplant insecticidal sprays can be applied, which is usually easier before plants are taken inside. Apply insecticides to upper and lower leaf surfaces, including leaf axils and other spots insects can hide.
ADVERTISEMENT If plants need repotting, that’s also easier outdoors, and removing at least some of the old soil will reduce the likelihood of insect eggs being present. It’s almost impossible though, to remove all the soil from a plant’s roots, which would also increase transplant shock. It’s also wise to quarantine plants that are brought indoors, separating them from other plants to limit the spread of insects that escaped our attempts to exclude them.
It can take several weeks to a month before hitchhiking insects multiply and become visible. Insects that are most problematic include aphids, which can be green, white, brown or red in color, and cluster around new growth at the tips of stems, and around flowers and buds. Aphids secrete a sticky substance called honeydew, leaving shiny residue on leaves or tabletops.
Mealybugs are also common, which look like small spots of white cotton where stems meet, on stems and on the undersides of leaves. Scale insects appear as small oval, white to brown bumps on stems and leaves. Spider mites are too tiny to see easily, until they produce fine webbing on stems and cause a speckled appearance on leaves.
Whiteflies rise up in a cloud when plants are jiggled, and fungus gnats appear as small black flies that flit around the soil surface. After plants have been indoors for a while, monitor closely, and if you do see a few insects, rub, wipe, or pick them off by hand, or dislodge with water. Clean up debris on the soil surface.
A cotton ball dipped in rubbing alcohol can kill insects quickly. For additional insurance against insect population explosions, apply systemic insecticides labeled for use on houseplants. The granules are added to the soil surface, with the rate dependent on pot diameter.
The insecticide is absorbed by roots and taken internally into the plant, killing insects as they suck the sap. ADVERTISEMENT Insect populations can explode rapidly and become difficult to manage. Being proactive and remaining vigilant can keep plants healthy and insect-free until they return once again to their summer home.
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