I have a canna-lilly. Outside it bloomed flowers. I put it inside in a bay window. It kept dying – it was too cold. So I put it by another window. Now its growing new stems. However, in the middle of the plant its still all dead. Do I empty out the soil, cut out the middle, and put the soil back? See pic
Thank you for writing with this very good question. Many gardeners in south central Ontario, home to Toronto, are unsure of what to do with canna lilies after the blooming season. Canna are an old favourite, loved for giving an outdoor garden that instant “tropical plant” feel, and they do thrive in the hot, humid Maritime climate that Toronto enjoys during the summer months. Also, canna is related to ginger, and banana! If you happen to break a section of canna leaf, you can smell the distinct fragrance of peeled banana skin.
First: Canna are native to warm, tropical climates, and not frost-hardy. Like banana, canna enjoy a minimum zone 7 and greater. Toronto is in gardening zone 6. Hence, in zones 6 through 2, to keep them alive, and viable, from year to year, gardeners have to ‘lift’ and store the plants, until the next warm growing season.
Second: Although often referred to as bulbs, canna actually sprout from underground stem material called rhizomes, helpful to know when it comes time to dig and divide. On that note, your plant appears to still be in the original pot in which it was purchased, and had not been ground-planted. Which is fine. And your instinct to bring it indoors was also fine. What you want to do next is “winter over” your rhizome sections, but not keep them growing, as you have hoped.
So, yes, to your question, carefully empty the pot, and let the soil fall away, so you can identify the healthy rhizome sections. Remove any soft, or rotted material. Look for sections that have nodes that will sprout into new plants. These will look like buds or a big bumps. Cut off any dead or growing stem material, as the rhizomes need to rest now. But do not put them back in soil — other gardeners have posed similar questions, and here is an excellent Toronto Master Gardener instruction on Canna Lily winter maintenance.
You have every chance of multiplying, and successfully growing, new plants from your original, and enjoy the experience.