As the fall season runs its course, a pressing issue for gardeners in the North is that of providing winter plant protection (or "overwintering" plants, if you will) for the plants that have brought so much joy to the landscape all spring and summer. What makes this issue complex is that the method -- or even the necessity -- of providing protection depends, to a large degree, on the type of plant in question (and on where you live).
As a result, I will organize the tips that follow according to plant category.
Protecting Tropical Plants in Winter
Is the plant in question a tropical one? Do you live in a climate where winters get cold? Then you will have to bring your specimen indoors -- one way or another -- in order to provide winter plant protection for it.
In some cases, this will mean bringing the entire plant indoors and using it in your interiorscaping during the winter. For example, if you are growing a palm tree in a pot and have kept it outdoors all summer, you will have to move it indoors at some point in the fall, so as to protect it from winter's cold temperatures (unless it is cold-hardy in your growing zone). If you can manage to keep it alive indoors (indoor environments are notoriously challenging for such plants, since they tend to be lacking in sunshine and, worse yet, in humidity), it can bring a lush, tropical feel to your home.
In other cases, it is the underground plant part (be it a tuber, corm, rhizome, etc.) of the tropical specimen that you will be bringing indoors, rather than the whole plant. Typically, such plant parts are stored during the winter in a place that is neither too cold nor too hot. Observe that this practice is necessary specifically for plants that are not hardy in your region.
There is no reason to dig and store away the bulbs of the spring-flowering bulb plants commonly grown in the North: not only do they not mind the cold, but some positively need it (which is why Southerners have trouble growing them). In the following articles, I offer tutorials on digging up and storing the underground plant parts of some of the most popular tropicals that grace the summer landscape with their blooms and/or foliage:
Take note, however, of a couple of points that I have learned from experience:
- It is not always necessary to overwinter these plants "by the book" (that is, in the standard way that you will read about all over the web). For example, in my tutorial on overwintering canna lilies, I supply the standard method for overwintering these splendid tropicals. But I also observe a shortcut that works equally well (or even better) in some cases. If you are a beginner, start by using the standard storage methods, but then experiment until you find what works best for you.
- While it is relatively easy to overwinter snake lily (Amorphophallus konjac) by digging its corm and storing it in a cool-but-not-too-cold area, first think twice about what kind of monster you may be bringing into your home. It produces one of the smelliest flowers in the plant world and blooms early in the season -- before temperatures have warmed enough in the North for it to be brought outside. This means you will have to live with the foul smell in your house (unless you own a greenhouse).
Protecting Perennials in Winter
How do you provide winter plant protection for perennials? A perennial listed as being suitable for your area often requires no winter protection. But if the perennial in question is only borderline-hardy in your region, creating a microclimate for it may be enormously helpful. More generally speaking, however, your greatest ally will be mulch -- if used correctly.
I offer two articles intended to inform you about mulch. The first will help those at an intermediate level (on the horticultural spectrum) to choose between the different types of mulch, while the second is an FAQ and geared more to beginners:
It is important to remember to remove mulch in spring at the proper time. If you do not, you may actually be doing more harm than good in trying to protect a plant in winter by applying mulch.
Protecting Ornamental Grasses in Winter
If the particular ornamental grass that you are growing is cold-hardy in your area, you should not have to go to any great lengths to give it winter plant protection. I recommend simply that you wait until spring to trim it. Here is why:
- By leaving the foliage in place, the grass' own above-ground growth furnishes a certain amount of insulation for the below-ground component (that is, the root system).
- As a bonus, this foliage is attractive and can supply considerable winter interest. Indeed, its winter-interest value may well be one of your chief motivations in deciding to grow an ornamental grass.
If the ornamental grass in question is borderline-hardy where you live, applying mulch around it may be enough to see it through the winter.
Protecting Shrubs in Winter
The problem of overwintering shrubs and trees is a bit different in nature. Assuming that the plant is cold-hardy in your region, the issue, generally, is not one of survival. However, the extremes of winter can wreak havoc with the appearance of your shrub or tree. Ice or heavy snow can accumulate on branches, weigh them down, and eventually snap them. Flower buds on deciduous plants can be damaged, depriving you of the beautiful spring blossoms to which you look forward so eagerly all winter. The foliage of evergreen shrubs such as arborvitae can turn brown, due to wind damage; that is why you will sometimes see them wrapped in burlap.
Applying mulch around shrubs and trees can protect their root zones during winter (which may be helpful if the plant is borderline-hardy in your area), but what about their above-ground growth? You do not have to worry about the latter issue with perennials and ornamental grasses, because their above-ground growth dies back in winter. But that is not the case with shrubs and trees. Mulch does not address the issue here. So what is a gardener to do?
For the latter, giving winter protection with a shrub shelter usually makes good sense. People sometimes wrap evergreen shrubs in burlap for the winter, but doing so deprives you of one of their chief selling points: namely, winter interest. I discuss the issue of whether or not to afford shelter to evergreens at some length in the following FAQ:
Protecting Trees in Winter
Obviously, mature trees will generally be too tall to wrap in burlap or enclose within a protective shelter. The best way to furnish winter plant protection for them is through proper irrigation prior to the cold-weather months, as detailed in the following resources: