Growing Green

By Robin Trott, Extension Educator

As the fall temperatures begin to cool off it is time to consider bringing in the houseplants you may have let “vacation” outside this summer.  Many houseplants will thrive outdoors during Minnesota’s summers, but they do not perform well or may even die if they are exposed to chilly temperatures.  Depending on the species, temperatures dipping below 45-50°F will cause damage.

Here are some tips to keep in mind as you prepare to bring your houseplants back indoors:

1.Before bringing inside, they must be inspected and treated for pests.  Aphids, mealybugs, white flies and other pests aren’t normally a problem when potted indoor plants are outside. But they can quickly turn into a major infestation during the winter if they are brought inside on the plants. Some experts recommend bathing or soaking plants before bringing them inside in a bucket of water with a mild dish washing soap.   If your plants are too big for the bucket treatment, first spray them with water to remove outdoor dust and soft bodied insects from the leaves.  Next, wash the top and undersides of the leaves as much as possible with water and dish washing soap and then rinse with water. It is important that the soapy water also get into the soil as it will help to kill any pests residing there, too. Once inside, check them with each watering for any sign of infestation and if spotted, treat religiously with an insecticidal soap until the problem is resolved.  Also wash the outside of the pots to remove dirt and to remove any unwanted pests that might be present.

2.Determine if your plants need to be pruned, separated, or repotted.  Some plants may have outgrown their pot and need something larger.  Others may be too large for the indoor space and need to be pruned, separated, or even propagated to start a new plant. 

3.Gradually reintroduce to the indoors – just like hardening off your new seedlings, your houseplants may undergo shock if abruptly brought from outdoor conditions to indoors.  This may result in yellow leaves, wilt, die back, or even death. Take it slow, and let it get acclimated to the indoors again a little at a time.

4.Position plant in sunny location – most likely your plant was exposed to a lot of sun outdoors so although you may want to move it back to a specific spot, you may need to temporarily put it in a very sunny window and gradually reduce its sun exposure to its permanent location.

Other plants that often get brought indoors for the winter are geraniums, even coleus, begonias, and impatiens.  All of these species can be propagated by using cuttings to generate a new crop for next summer. Cuttings should be approximately 4-inches long and be taken from only vigorous, healthy plants. Remove the leaves from the bottom portions. One option is to make a forsythe pot, step-by-step instructions can be found here: https://studylib.net/doc/18313310/making-a-forsythe-pot. This propagation option allows for cuttings to form roots in a light growing medium like vermiculite and have a consistent moisture supplier with a porous corked clay pot in the center that you add water to.

Next week I will write about overwintering geraniums, and some tips on propagation.

Until next time, happy gardening!