Gardenbite: Tips for overwintering potted perennials | #GoodGrowing

Welcome to the Good Growing podcast. I am Ken Johnson, horticulture educator with the University of Illinois Extension, coming to you today from Jacksonville, Illinois with a gardenbite. And on this week's Gardenbite, we're gonna talk a little bit about overwintering potted plants. So maybe you've had a situation, where you've gone a little bit overboard buying plants in the fall. Maybe you found a good sale or something like that and you run out of room or run out of energy to get them all planted or maybe even time, and figure you can wait until spring, to get them planted only to find out that most, if not all of them, have died.

Or maybe you've had a container planter with perennials in it, and you excitedly wait for them to resume growth in the spring only for that to never happen. So perennials in pots are going to be subjected to much harsher conditions compared to those plants that are planted in the soil. Because of this, even if they are hardy to the area that you live in, that we live in, they can be damaged or killed from cold temperatures. Fortunately, there are some steps we can take, though, to try to get these plants through the winter so we can enjoy them again come spring. Before we start moving pots around, though, there's a couple things we wanna do.

First, we wanna make sure those plants are are well watered, and we're gonna want to check this throughout the winter, those moisture the soil moisture levels throughout the winter. Even after the above ground growth has gone dormant and stopped for the year, roots of the plants can continue to take up water, and this is going to be especially important for evergreens to help prevent, winter desiccation winter burn or desiccation. So these evergreens are gonna continue to transpire throughout the winter, and our cold, dry airs can really suck out a lot of moisture from those plants. So those roots need to be able to have moisture they can access in the soil to help prevent this. And in addition to providing water to the plants for the roots to take up, moist growing media is going to freeze much more slowly than dry media, and it's going to offer additional protection to our plants.

So make sure they are well watered, and you continue watering them throughout the winter if needed. So the most common way plants are probably going to be overwintered is going to be storing them indoors, something like an unheated garage, a shed, cool, cold basement, are gonna make place good locations to put potted perennial plants to overwinter. Now many perennial plants need a cold dormancy period in order to properly bloom or grow again in the spring. So if your garage or basement is too warm, temperature should be in the 20 to forty, forty five degree range, you may need to look elsewhere. But if you can meet those temperature requirements, now this could be a good option.

And this is gonna be a really good option for plants that are not hardy, perennials that are not hardy to the zone you live in. So we can put those in there. Once it starts warming up in spring or those plants resume growth, we can start moving them into sunnier locations and then finally outdoors. The second option would be to sink the pots into the ground. So by placing these pots in the ground, the surrounding soil can insulate the pot and the plant roots, providing protection from those extremely cold temperatures and temperature fluctuations similar to a plant that's just planted in the soil directly.

And then once the danger of hard frost has passed, those plant those pots can be removed from the holes that they've been put in and then placed again out in the landscape. And if you've got if you have a more decorative pot that you're growing in, you can sink an empty pot and then put your pot inside of that. So a pot inside of a pot to keep those pots a little bit cleaner if you're concerned about them getting dirty or the appearance of them. If digging a hole in the ground isn't an option or the pot's too large or too heavy, something like that, you or you have a lot of them, you can group pots together in a protected location. So we wanna look for an area that doesn't receive really strong winds or doesn't have too much sunlight, because too much sunlight is going to could potentially warm up those pots, we get some pretty drastic temperature fluctuations with that.

So some areas like a north or east side of a building could be good options, especially if you've got some protection from wind. Once the pots have been clustered together, they can be mulched heavily with straw, wood mulch, or leaves. And, you know, here in October, November time frame, there's a lot of leaves out in the landscape, so I can collect those and put those around plants. You may need to contain them, in some way, but, those are gonna help insulate those plants, even more help with with cool temperatures and those temperature fluctuations as well. And then once growth resumes in the spring, we can remove the mulch and then return the pots to wherever you want them in the landscape.

And, again, this is this is how we're gonna do this for hardy perennials, non hardy plants, plants that aren't gonna survive outdoors, geraniums and stuff like that. Hibiscus, again, we probably wanna put those indoors because they're not gonna survive really cold temperatures. They may be subjected to outdoors. So why bother going through all of this trouble? So most plants' roots are going to be far less cold hardy than their above than the above ground parts, the stems and the trunks.

This usually isn't an issue when the plants are planted in the ground because the soil is gonna insulate the roots and protect them from those cold temperatures. And if we have any snow cover, that's gonna further insulate plants. And even though potted plants are going to be in growing media, the amount of media is is small. It's going to get much colder than the soil in the ground and the surrounding landscape. So if you are going to be trying to overwinter potted plants outdoors, especially long term, it's probably a good idea to look for plants that can survive a hardiness zone lower than the one we are in.

So general rule is to select the plants that are two zones different than the zone that we're in. So here in Central Illinois, depending on where you live, we're Zone 5 or six. So we'd wanna look for plants that are hardy to zone three or four, if we're gonna overwinter these outdoors in a potting in year after year after year. As an aside, if you have any pots that you're done growing in, maybe you've had annuals or something like that in there, those containers can be damaged from freezing and thawing conditions if the growing media is left in there throughout the winter from that freeze thaw cycle. And if they're exposed to the sun, especially plastics, those pots can become brittle and break down over time.

So we want to remove the growing media, store them upside down, or again, put them in a protected location to help prolong the useful life of those pots if you're going to be reusing them. Well, that's all I've got for you for this week's gardenbite. Hopefully, this will help you make a plan for how you can overwinter your plants and hopefully, do this a little more successfully so you can enjoy them again come spring. The Good Growing podcast is a production of University of Illinois Extension. Listeners, thank you for doing what you do best and that is listening, or if you're watching on YouTube watching.

And as always, keep on growing.