Growing Wisdom

Keeping Insects Off Houseplants In Winter

Each fall I bring in about 25-30 houseplants which have been outside since early May. There really isn’t a good reason for all this work. Many of the plants I have could be easily replaced and they are all inside 7 months of the year as opposed to being out only 5.

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Nevertheless, I like the way the plants look with 20 odd weeks of growing in the sunshine and they seem to be quite healthy in October when I return them to the sunroom.

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Some of my plants end up in the garage. Those plants are the ones that can handle a freeze or two, but don’t want to be exposed to the full onslaught of the elements. While the plants love the summer breeze, sunshine and natural water, they are exposed to bugs. In the winter when our homes are dry and warm many of these bugs can come alive and wreak havoc on the plants. I find by treating them in the fall prior to brining in them inside they can make it through the winter and early spring bug free and thus be a lot healthier come the spring when it’s time to move them outside once again.


I always take a two pronged approach to treating the plants. First, I mix a systemic insecticide like imidacloprid into the soil. Now, I am not a fan of synthetic insecticide and this one is reportedly quite harmful to wildlife. However, it only lasts about 3-4 months at best and there aren’t any wild life issues inside my house. Then I treat the plants with a synthetic horticultural oil to smother any eggs that might be on the leaves etc.

This approach has worked quite well. Spider mites are still a problem later in the winter so I usually keep a spray bottle of Neem oil or horticultural oil handy and treat the plant outside if it’s above freezing or in the garage or basement if it’s very cold. The systemic doesn’t work great on spider mites.


You should also keep your plants on the drier side during the winter as they are not growing much and the roots can rot in cold damp conditions. Many of my plants are in the sun-room which can get quite cold at night. These steps seems to keep my plants from a major outbreak of insects and reasonably healthy throughout the colder months.

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