by Connie Oswald Stofko
Canna lilies are tall, impressive plants that I’ve long admired in Western New York gardens. So when I visited the Master Gardener plant sale in Buffalo this spring and saw a whole area with cannas, I toyed with the idea of actually buying one.
When a helpful Master Gardener explained the different varieties, I admitted I was hesitant to buy a canna lily because I’m a lazy gardener. I know you have to bring in the bulb for the winter.
The Master Gardener smiled and told me I didn’t have to do that.
“You can treat it like an annual and buy another one next year,” she said.
I actually hadn’t thought of that. I checked out the price and bought one.
In this article, we’ll talk about overwintering plants or bulbs, that is, keeping them in a dormant state and then reviving the plant again in spring. We’ll also take a look at bringing plants inside and trying to keep them growing all winter, or at least for a few extra weeks.
And I’d love your comments on which plants you overwinter and which you don’t bother with. Please leave a comment below.
Decide which plants to bring inside for winter
Let’s start with plants you don’t bring inside for the winter. You don’t have to worry about plants that are perennials in Western New York, such as hostas, daylilies, roses and coneflowers. They tolerate our cold winter temperatures and even need a period of cold to be healthy, so don’t bother trying to bring them inside.
Then there are houseplants. We call them houseplants because we use them inside our houses, even during the winter. If you set your houseplants outside for the summer, you will need to bring them back inside. Care for them as you have in the past. Tip: When you bring houseplants inside, make sure to look for pests.
The plants we’re talking about are plants you bought for your garden. They are plants that won’t survive our winters and won’t come back on their own next year. You would have to buy again next year if you don’t bring them inside. (We often refer to these as annuals, although in the warmer area they come from they are perennials.)
David Clark, CNLP, who teaches the great horticulture classes at the Buffalo and Erie County Botanical Gardens, shared some ideas with me. There are no hard-and-fast rules about which plants you should overwinter or exactly how you should care for the plants during the winter.
“Experiment!” Clark said. “What can you get to work?”
Here are some guidelines to help you decide which plants you should bring in for the winter.
Plant is expensive
If you paid $50 for one plant, you probably want to overwinter it, Clark said.
And if you paid $10 or $20 for a plant and you want to fill a garden bed with lots of those plants, that will be pricey, too. Try overwintering those expensive plants.
Plant is important to you
If you’ve been searching for years for a plant and it’s rare, try to overwinter it.
“I have an eight-year-old passion flower that is precious to me,” Clark said. “It’s a Russian variety. I really baby that thing.”
Process is easy for you
For Clark, it’s fun to overwinter all kinds of plants, but if it’s too much work for you, you don’t have to do it, he said.
You may feel bad about throwing, say, healthy dahlia bulbs on your compost pile instead of trying to overwinter them. If so, buy a different plant! There are many that will work just as well in that spot.
You have proper conditions
If you want to overwinter bulbs or plants in a dormant state, you need a cool, dry area, such as a basement or sunporch. If you don’t have an area that, you don’t have the proper conditions.
If you want to keep tender plants growing inside through the winter, you need proper lighting. A sunny window isn’t going to be enough.
“The brightest window in your house equals the shadiest spot in your garden,” Clark said. He has a basement full of grow lights. “The limiting factor is the amount of light you have. If you don’t have enough light, the plants will get spindly and lanky, and the bugs will like them.”
For some plants, you would need a greenhouse to keep them growing all winter.
How to overwinter tender plants
Let the plant go dormant in a pot
For plants such as caladium, lantana (which Jim Charlier from Open Gardens overwinters) and passion flower, you can just keep the plant in its pot.
Find a cool spot, such as a basement or sun porch. Ideally the temperature would be between 40 and 50 degrees Fahrenheit, Clark said.
Once a month, water the plant sparingly. You don’t want the root or tuber to totally dry out. On the other hand, you don’t want to soak the soil so heavily that water comes out the bottom.
Store tubers outside the pot
Previously we published an article on overwintering tuberous begonias. This method will also work for plants such as dahlias, elephant ear (alocasia and colocasia) canna lilies and gladiolus. Also see a discussion about overwintering geraniums here.
Keep the plant growing until spring
Keeping the plant growing through winter is a little more difficult than putting it into a dormant state.
Pat Gurney, who shared her Orchard Park landscape on Open Gardens, mentioned she wouldn’t bother bringing coleus in for the winter because it would be weak by spring. I share her sentiment because I don’t have even a sunny window, much less grow lights.
Clark disagrees. Every year a friend of his took cuttings and propagated them by placing the cuttings in water on a windowsill.
“I think it’s a worthy plant to bring in,” he said. It’s super easy to propagate the cuttings and coleus does well in shade. See more about coleus– cuttings, propagating & getting it through the winter– in this article. Make sure you read the comments, too.
With the help of grow lights, Clark will attempt to keep a five-foot tall lemongrass plant growing inside all winter. Even if it doesn’t grow all winter, he can at least use the herb in cooking for some weeks or months.
Plants to bring inside for a little while
You can extend the growing season a bit for some plants by bringing them inside.
Bring in pots of marigolds, zinnias, impatiens and other annuals to get a few more weeks of enjoyment from them, Clark said. An alternative is to cut some stems from the plant and use the flowers in a vase.
You can also keep many herbs, such as rosemary, marjoram, tarragon, oregano and chives, growing inside for some time, he said. If you have an under-cabinet flourescent light in your kitchen, you might be able to keep them growing longer than if you just set them in a window.
Clark leaves parsley outside because it’s a biennial. It grows from seed the first year, and when the plant wakes up again in spring, you will get more leaves before it flowers. But if you want fresh herbs for cooking, bring it inside.
Vegetables and fruits can get an extended life inside. See this article on bringing your tomato plant inside.
If you have very good light, such as tabletop grow lights, you might even be able to grow strawberries (Fragaria vesca), Clark said. No, you won’t get many berries as you would outside, and the berries you get will be small, but it’s fun to be able to eat fresh strawberries in winter.
What plants do you overwinter or bring inside for a few extra weeks of enjoyment? What plants have you decided not to bother with? Please leave a comment below.