Good Growing

Now that night temperatures are starting to cool,  it’s time to start thinking about bringing houseplants back indoors for the winter. On this week's Good Growing Podcast, Ken Johnson discusses some steps we can take to successfully transition our houseplants indoors, as well as some tips on their care over the winter. 


Want to read more about moving houseplants indoors and houseplant pests? Check out these blog articles:
  • Tips for moving houseplants indoors and overwinter care: https://extension.illinois.edu/blogs/good-growing/2022-09-09-tips-moving-houseplants-indoors-and-overwinter-care

  • Houseplant pests and how to manage them: https://extension.illinois.edu/blogs/good-growing/2022-01-14-houseplant-pests-and-how-manage-them

Contact us! 
Chris Enroth: cenroth@illinois.edu
Ken Johnson: kjohnso@illinois.edu 

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Creators and Guests

Host
Chris Enroth
University of Illinois Extension Horticulture Educator serving Henderson, Knox, McDonough, and Warren Counties
Host
Ken Johnson
University of Illinois Extension Horticulture Educator serving Calhoun, Cass, Greene, Morgan, and Scott Counties

What is Good Growing?

Talking all things horticulture, ecology, and design.

Ken Johnson:

Welcome to the GoodGrowing podcast. I am Ken Johnson, horticulture educator with University of Illinois Extension coming to you today from Jacksonville, Illinois with a garden bite. And now that we're into the middle of September and we're starting to draw near and nearer to fall, it may not seem like it, but it's time to start thinking about bringing our houseplants back inside for the winter. Many, if not most of our houseplants are actually native to tropical and subtropical climates, and while they do great outdoors during the summer, they're not going to do too well during the winter and cannot tolerate cold temperatures. So as that thermometer starts getting consistently below 55 degrees, at night, it's time to start thinking about bringing those houseplants back inside.

Ken Johnson:

Before we start bringing our houseplants back indoors, there's a few things that we want to do. First, we want to make sure to inspect them for any insects and other pests that may be on there. Insects like aphids, whiteflies, mealybugs, scales, as well as things like spider mites are some pests that we're going to commonly find on plants outdoors. If they are brought indoors, many times those populations rapidly increase, and they will spread to other plants because there's no longer any natural enemies that can control them indoors. We may have low populations outside, natural enemies are removed, and those populations explode, and they can actually kill plants if those populations get high enough.

Ken Johnson:

One way we can try to get rid of any pests that may be present on our plants is to spray them off with a hose, a nice steady stream of water onto that, that'll knock off a lot of pests. You do that a couple times, that'll get rid of most of the pests we may have on our plants. Now pests that are firmly attached to plants like scale, those can be scraped off with a fingernail, you can get a credit card, or wipe them off with a wet sponge. You want to try to get as many of those off as you can so those populations don't rapidly increase once they get indoors. If washing them off or scraping those insects off doesn't work, there are some insecticides we can use, products like pyrethrins, insecticidal soaps, and neem can be used.

Ken Johnson:

If you are going to use insecticides, just make sure you read that label and follow all the instructions before you apply those to the plants. And if your plants are infested, they're completely covered, it may be best to dispose of those plants and purchase a new plant instead of risking bringing those problems into your house, where they can spread to other houseplants. In addition to checking the foliage and the stems of the plants, it's also a good idea to check the soil. Oftentimes insects like earwigs, ants, crustaceans like roly pollies, or pill bugs, sow bugs can inhabit the soils of our potted plants. So if you have those insects or other critters in there, flush those pots out with water, water them real well, let it drain out, and many times that will drive out anything that's living in the soil.

Ken Johnson:

If you have ants that have taken up a home in your potted plants, it may be a good idea to repot that plant before you bring it inside. Flushing them out with water may not be enough to drive that ant colony out. And then once you do bring your plants indoors, at least from the inspect insect perspective, it's a good idea to keep them isolated from other plants for a couple weeks. This will help prevent any pests that you miss from building up and spreading to other plants that you have indoors. After three or four weeks, if you haven't noticed any pests on the plants that you've brought indoors, it should be safe to move them closer to your other plants, but you still want to monitor those every once in a while.

Ken Johnson:

So if there are any pests that are present, you can get on top of that right away. So once plants are brought indoors, it's likely that their growth is going to considerably slow down inside. So we're going to need less water and less fertilizers for those plants. So for most plants, we should allow the soil to dry slightly between waterings and stop fertilizing altogether until the spring, until growth resumes and we start seeing new growth on those plants. So some things we need to think about indoors for our plants, first is going to be light.

Ken Johnson:

Light levels indoors are going to be much lower than they are outdoors, even compared to shaded areas. And this reduction in light intensity often results in yellowing leaves and leaf drop. Eventually plants will begin to produce new leaves and adjust to those lower light levels, but it can be a little bit alarming when all of a sudden plants look start looking pretty crummy when we bring them inside first thing in the fall. To help get your plants acclimated to lower light levels inside, you can try moving your plants into shaded areas in your landscape for a week, and then start moving them indoors for a day or two at a time, gradually increasing the amount of time indoors and reducing the amount of light they're receiving. Kind of think of it as reverse hardening off.

Ken Johnson:

In the spring, we're slowly introducing plants to more sunlight so they don't get burned. In the fall, we can slowly introduce them to getting less light, so we make that transition to lower light levels a little less severe once they're inside full time. Once our plants are moved indoors full time, we want to put them next to the brightest, sunniest window possible. For most homes, this is typically going to be the south or west facing window. If you can't give your plants enough light, you may want to look at supplemental lighting and house plants will vary on how much light they need and how much and how little light they can tolerate.

Ken Johnson:

So keep that in mind as well. Temperature is another thing we need to think about when bringing our plants indoors and where we are going to place our plants. So we want to try to avoid placing plants in areas where they will be exposed to drafts or too close to heat vents. For the most part, houseplants are going to prefer daytime temperatures between sixty and seventy five degrees, and then about 10 degrees cooler at night. So if you live in an old home that has very drafty windows, you probably don't want to put your plants too close to those windows.

Ken Johnson:

Alternatively, you don't want to put your plants right next to a heat vent that may get too hot and may dry your plants out too. Next, when it comes to watering, if you're not sure if your plants need water, there's a couple ways we can check this. First is the old finger test, so stick your finger into your potting media up to about your second knuckle. If the media is still moist, for the most part, you probably don't need to water. Alternatively, could lift the pot if it feels light, it may be time to water.

Ken Johnson:

It may take a little bit of time to figure out what that weight is supposed to be depending on the pot and the plant and all that, but over time you can kind of get a feel by lifting that pot whether or not those plants are going to need to be watered. Our houseplants can be watered by top or bottom watering. If top watering, make sure you apply enough water so that it comes out of the drainage holes at the bottom of the pot, again make sure you have drainage holes in your pots, if you don't, repot them before you bring them inside. Once that water drains out, want to make sure you discard any of that water that collects in that plant saucer. We don't really want those pots sitting in water all the time.

Ken Johnson:

That can get waterlogged soils and cause root rot issues potentially. If your plants are really dry, you haven't checked them in a while, you forgot about them, you may need to repeat the process several times to thoroughly remoisten that potting mix. Sometimes potting mixes, when they get really dry, actually kind of repel water, so it can take some time to get that growing media properly rehydrated. If you want to water from the bottom, fill your plant saucer or fill the sink with a few inches of water, let your plant soak in that, and then once the potting mix on the top of this pot is moist, the plant can then be removed and put back in its permanent home. Or if you put that water in the saucer, you can then discard it.

Ken Johnson:

Every once in a while, pots of houseplants are placed inside of a more decorative looking pot that does not have drainage holes. See this a lot during the holidays, things like poinsettias particularly this happens too. If you have pots like this, make sure that outer decorative pot isn't filling with water. And again, if it is, make sure you discard that so those pots aren't constantly sitting in water. Last thing we want to think about in our homes when it comes to house plants is the humidity.

Ken Johnson:

Humidity levels in our homes are going to be much lower than they are when the plants are outside. Additionally, again, most of our house plants come from more tropical areas and do best with higher humidity levels than we typically see indoors during the winter. In some cases, indoor humidity can be as low as 10 to 20%, especially when we're running the heat. Dropping leaves is one of the most common symptoms when plants do not have enough humidity around them. So there are several different ways we can try to increase the humidity around our plants to try to prevent this.

Ken Johnson:

Kitchens and bathrooms often have higher humidity levels compared to other rooms in your home. So if you have the space and you have enough light, consider placing your house plants in these rooms. You can place your plants close together. Again, make sure you isolate any plants that have been outdoors and make sure they don't have pests on them. Your plants are real close and makes it easy for those pests to spread from plant to plant.

Ken Johnson:

Plants are going to lose water through transpiration, and if they're clustered together, this can create a microclimate with a little bit higher humidity compared to the rest of the home. You can also place your plants in a shallow tray with gravel and water. As that water evaporates, it will increase the humidity in the area. You want to make sure that the pots are not sitting in the water, but they are sitting on that gravel and the water is in the gravel. People commonly do this with orchids.

Ken Johnson:

If you have a lot of plants, run a humidifier you to help increase the humidity in that area near the plants or in that room to have the plants. And one thing that is commonly recommended for helping with humidity is misting plants. However, misting really only increases humidity levels for a short period of time and for misting to be effective, you would need to mist plants every few minutes or have a misting system set up. For most people, this is not going to be the most practical way of increasing humidity. So that's all I've got for you for tips on moving your house plants indoors and caring for them over the winter.

Ken Johnson:

Thanks for listening and keep on growing.