Whenever I see cannas growing in a landscape, I always say to myself…Tom you need to get some of those. But then I move on and forget. Maybe this coming garden season will be different.

Cannas are an impressive plant. First of all, with a little extra care, they come back every year so that makes them a good investment in my book. And they grow to an impressive size with most cannas growing to between 3 and 5 feet in height. While there are some dwarf varieties that only grow to about 1.5 to 2 feet in height, I still lean toward the taller ones. I am told there are also some varieties that grow to about 8 to 10 feet in height.  

While cannas typically grow from rhizomes (an underground stem capable of producing new roots and shoots), you can grow them from seed. For those who want to give growing cannas from seed a try, here’s what you need to know.

While you may have to look a bit to find them, you can find canna seeds. The best time to start canna seeds is in mid-February, so it’s time to start looking for seeds. Once you acquire your seeds, you’ll need to soak them in water for 12 to 24 hours. This soaking will soften the seed coats and increase the likelihood of germination.

Next, you’ll need to gather up your seed starting supplies. You’ll need a seed tray and a good seed starting mix. Seed starting mix is a much lighter and airy medium which provides a good mix in which to start your seeds. You will also get better results if you use a seed starting heating mat since the seeds will germinate faster and more easily in a temperature of between 70 and 75 degrees. You’ll also need to place your seeds in a place where the get good light. You can do this with natural light but grow lights will simplify your life. Be sure to cover these newly planted seeds with a plastic cover or you can even use clear plastic wrap to help retain heat and moisture. Just be sure to remove the cover once your seeds have germinated. Your seed should start to germinate in about 7 to 14 days.  

As your little baby cannas begin to grow, you need to transplant them to a container filled with a good quality potting mix. Keep them watered and if your potting soil doesn’t come with added nutrients, you might need to add a little fertilizer.

When we get to around mid-April when the danger of frost has passed, you can begin to move you little canna plants outside. Be sure to harden them off which means gradually introducing them to the outdoors rather than just planting them in the ground and hoping for the best.

Hardening off your plants can take a week or so depending on how diligent you are in the process. Start by placing them in a shady location and then each day, increase the amount of sunlight they receive. Once they get acclimated, they are ready to go in the ground.

Now, if seed starting is not your forte, you can purchase canna rhizomes in the spring. I just checked online, and you can order canna rhizomes now, but they won’t ship until March.

Canna rhizomes can be planted in the spring after the danger of frost has passed. Individual rhizomes should be planted horizontally about 4 to 6 inches deep, placing them about a foot apart. For you overachievers, you can plant your rhizomes indoors in a pot in early March if you would like to get a jump on blooming season.

The best location for your cannas will be in well-drained soil where they get what we call “full sun.” Full sun typically means at least 6 hours of direct sun each day but the more sun the better for cannas. They need well drained soil since those rhizomes can rot if planted in soil that is wet most of the time. Even though they like well-drained soil, you’ll still need to water them once a week during the growing season. As the season progresses, you can remove the flowers that whither. This will encourage production of additional blooms.

Now, I said your cannas will come back each year, but since cannas are rated for growing zones 9 and 10, they don’t overwinter well outdoors…meaning you’ll want to dig up those rhizomes at the end of the season and store them in a cool, dark place for next year. Now I know, some of you are going to say, “I never dig up my cannas and they come back every year.” That’s great, just know that at some point, the cold will likely take its toll, and you’ll have to replace them.

Another good thing about cannas is that over time, those rhizomes tend to get bigger and push out shoots. These shoots can be separated and planted separately to provide you with more canna plants, or canna plants to share.

While cannas are pretty tough, they can fall victim to canna yellow mottle virus, bean yellow mosaic virus, cucumber mosaic virus, and tomato asperity virus. Virus’ in plants is never good since the virus will not only take out the host plant but spread to other nearby plants. So, if you start to see leaves that are discolored with a yellow mosaic pattern or appear to be dying along the veins, you will need to remove the plant.

Hopefully, this will be the year that I get my canna act together. See you in the garden!

You can get answers to all your gardening questions by calling the Tulsa Master Gardeners Help Line at 918-746-3701, dropping by our Diagnostic Center at 4116 E. 15th Street, or by emailing us at mg@tulsamastergardeners.org. OSU Ag. Comm.