by Val McGruder
The first year I planted Canna’s, they were lovely and I delighted in how tall and vibrant they were. In the spring, I anxiously awaited their appearance but alas…..nothing! My sister in law had given several to me but neglected to tell me that they needed to be dug up and stored over the winter months. That was before I became a master gardener. I have since learned a bit more about them.
Canna Lilies are a tropical plant (zone 7-10+), so of course they aren’t hardy in Minnesota (zone 4). Now that fall is here, the days are colder and we experience our first frosty mornings. Along with our other autumn chores, we need to take steps to dig up and prepare our Canna rhizomes for overwintering.
After a frost is the preferred time to tackle this job. The first step is to cut the stems to 3-6 inches. Use a garden fork or shovel to carefully dig around the lily and lift it from the soil. Try not to cut through the rhizome. Shake excess soil off and let the rhizomes dry at least overnight. I brought mine into the basement to dry and brushed off any soil still clinging to it the next day. You can also trim the long roots and trim more off the stem if you wish. If a rhizome is very large, simply snap them into smaller sections. Each section needs an “eye”. To store them, you can use a large container. I used a Rubbermaid bin. I use peat moss and start out with a one-inch layer at the bottom of the bin. I add the rhizomes making sure they do not touch each other. Keep adding additional layers of rhizomes between each layer of peat moss. You can use newspaper to finish off the box but do not use the cover for the box because it can cause condensation. Another way to store them is to use brown paper lunch bags, one rhizome per bag. They should be overwintered in a dry location between 40-50 degrees. Checking them once a month for signs of root rot and mold is recommended. Toss any that feel mushy or less than healthy. It is time consuming but what else are you going to do in the dead of winter?
I noticed one day last winter that I had four Cannas at least a foot tall, peeking out of the box. It seemed to me they were asking: “Canna come out now?” I discovered that my basement was not cool enough and they were ready to start growing. Once the process begins, you can’t just cut them off and put them back to bed. I planted them each into large pots and placed them in front of a south-facing window. They each grew to 6+ feet tall and bloomed in the month of March. It was another lesson but also a rare treat to witness the beauty of these gorgeous flowers in the dead of winter.
For further information check out the U of M extension site: https://extension.umn.edu/