If you have houseplants outside, it’s time to start preparing them to come back inside for the winter months. Summer is a great time to let your indoor plants enjoy the sun, humidity, and heat. As fall approaches, night-time temperatures may dip below what most houseplants can tolerate, and it will eventually be too cold to keep them outside. Let’s take a look at the steps needed to prepare them for returning indoors.
Most houseplants need a warm environment and need to be brought in when temperatures fall into the 40-50s. Though fall days are often still warm, nighttime temperatures can dip below freezing. Exceptions to this guideline are a few succulents and cacti that tolerate 40-degree weather and fall annuals like pansies and mums that tolerate light frost. In most cases, you will need to bring houseplants inside when the temperature is below 50 degrees.
Before bringing in houseplants, it’s a good idea to check for disease or insects that may hitch a ride inside. Common insects you may see come indoors with plants are: fungus gnats, aphids, spider mites, actual spiders, and potentially mealy bugs or scale. Checking all houseplants before bringing them inside is recommended. As a preventative measure, apply a houseplant insecticide 3 weeks before bringing plants indoors permanently. Often a soil-applied systemic insecticide is best for “just in case” instances. If you are currently treating a known issue, often a foliage application is best to reduce insect numbers quickly. Fungus gnats are a year-round issue for most houseplant owners. Though they do not damage plants, they are a nuisance indoors. Fungus gnats prefer wet/moist soil; avoid overwatering and let soil dry out in between each watering. A combination of yellow sticky traps and soil-applied mosquito bits (BT, a beneficial bacterium for controlling larvae), will do the trick.
It is good practice to quarantine new additions or houseplants returning indoors. Put these plants in a separate area, away from existing plants. This will keep new pest issues from arising in healthy plants. Many of the listed pests above will move from one plant to another if they are in close proximity. They are also often tough to control once a population is established within indoor plants. Unlike outdoor plants, there are no environmental checks and balances, such as natural predators or rainfall. In some cases, repotting a houseplant using fresh soil and a clean pot is recommended, especially for hard-to-control pests like mealy bugs. In rare cases, pest issues are not worth the trouble, and discarding infected plants may be the best option.
Don’t be alarmed if plant leaves start to turn yellow and fall off once inside. This is very common for a lot of houseplants when they transition from outside to inside. In addition to the change in environment, the light duration becomes shorter, giving the signal for some plants that it’s time to go dormant. This is often the case for tropical plants like hibiscus, Ficus, and citrus trees. They will recover if they are properly cared for once
indoors.
Always follow pesticide labels and directions for use; not all insecticides are good for indoor use or on all houseplant varieties.
For more information on pest control and houseplant care, visit the UMN-Extension houseplant care website at extension.umn.edu.
For questions about this article or local assistance, please contact Clay County Extension Educator, Jill Patrie at 218-299-7338 or [email protected].