Canna roots must be dug, stored for the winter
Question: We had several huge canna lilies in our garden this year. They have now been killed by these recent cold temperatures. Is it too late to dig them up? If we do, how do we keep them through the winter?
Answer: Cannas are beautiful, tropical plants that make a bold statement in garden beds and borders. I also grow cannas in large containers and use them to create a tropical setting on our patio. Their broad leaves, tall stature and colorful blooms of cannas are adored by many gardeners.
Cannas come in a wide range of colors, both in terms of their leaves and their flowers. Blooms are typically shades of red, orange, yellow and peach, while the leaves can be bright green, deep red or even striped with various hues. There are many newer varieties of cannas on the market recently, each with its own merits.
And, even if you don’t think you have room for standard-sized cannas, which can reach 6 feet tall, there are also some dwarf cannas available at local garden centers in the spring that top out at 1 to 3 feet in height.
After enjoying the plants all summer long, fall’s arrival serves as your sign to prepare the tuberous roots of cannas for winter storage. The plants are not hardy this far north, so the only way to enjoy the same plant for multiple years is to remove the roots from the ground and properly store them. With any luck, your canna collection will quickly expand, and that one plant will turn into many plants in just a season or two.
Here’s the process I use to dig and store cannas at the end of the growing season.
1. Begin the process when the leaves have been killed by the first hard frost. Don’t wait too long or the ground will freeze, turning your canna’s roots to mush. For now, the ground is still warm, so the roots are well insulated.
2. Cut back the stems of the cannas to about 3 inches in height. Leaving a bit of stem attached to the roots will keep them from drying out too much over the winter. Plus, the stems make a nice little handle for moving the root clumps, which can grow quite large and heavy.
3. Brush off as much soil as possible from the thick roots. If the day is warm and dry, you can use a sharp stream of water to wash off the roots. After removing most of the soil, spread the root clumps out on a sheet of newspaper and put them in the garage or another cool, dry location. Let them dry out for four or five days.
4. Once the root clumps are dry, brush off more soil if any remains. Then, fill a cardboard box with about 4 inches of dry peat moss or vermiculite. Don’t use wet materials or the roots will develop rot. Layer the roots over the peat moss in a single layer.
5. Add more peat moss or vermiculite over top of the roots. Then add another layer of roots, continuing to alternate the layers until the box is full. Make sure there is at least 2 inches of peat moss or vermiculite above the top layer of roots.
6. Close the box by overlapping the flaps in an alternating fashion. Do not seal or tape the box closed. The small opening between the flap layers provides a bit of air exchange.
7. Store the box in a cold, dry location, such as an unheated attached garage or a basement. Ideal temperatures are 30 to 50 degrees F.
When spring arrives and the threat of frost passes, it’s time to open the box and split the root clumps if they need to be divided. Splitting the clumps is easy. Just crack the roots apart or use a knife to cut them into sections.
Replant the roots into the garden and prepare for another year of gorgeous blooms.
Horticulturist Jessica Walliser co-hosts “The Organic Gardeners” at 7 a.m. Sundays on KDKA Radio with Doug Oster. She is the author of several gardening books, including “Attracting Beneficial Bugs to Your Garden,” “Good Bug, Bad Bug,” and her newest title, “Container Gardening Complete.” Her website is jessicawalliser.com. Send your gardening or landscaping questions to [email protected] or The Good Earth, 622 Cabin Hill Drive, Greensburg, PA 15601.