Canna is a very vigorous grower that does not require fertilizer in normal garden soil. The pot size is an issue mainly to keep the plant from falling over as it puts on more height. Al

I try to plant around mid May. The best tip I have for you is, bury the rhizome, and water a plenty! :)

I managed to let my spring delivered canna "bulbs" set around in their bags until about 2 or so weeks ago. The ones that were still good are up and thriving though I don't know if they will bloom this year. We do have a long growing season here so I am hopeful.

You won't lose them. You're in a zone where you may be able to grow them all year, depending on your winter. Cannas continually produce new stalks which will bloom even tho old stalks may be exhausted. Here, we cut the cannas down when a frost kills the foliage, which was just in the last week or two. Do you get frost? I wouldn't cut the foliage until the last possible minute. It will continue to absorb energy for the rhizomes. Throughout the season, as old stalks finish blooming (each stalk may have two or three flushes of blooms), you can trim down the old stalks so new stalks can take in nutrients and sunlight. You can cut the stalks to about an inch tall. Don't worry, you're not going to hurt the cannas. In fact, in your zone, they may be "weeds" for you someday. Believe me, if I haven't killed them here in zone 7, with my neglect, they're safe with you. LOL