I usually plant some type of flowers or coleus with my cannas in pots.
Betty is a zone 4 so she probably has a very short summer. Even shorter than my summer. Canna bulbs purchased now and planted in a pot in May will not start to grow until June. Will be half the size of adult by the end of July. At best she is going to have August of a pretty pot.
I keep mine in the pots are winter and keep them just on the side of half alive. Put them outside as soon as our temps are above freezing about April. Good years the are looking perfect May early June. During that time they look good but I have other things in the pot for interest until the Cannas are show stoppers and the other plants in the pot compliment the pot.
The one thing I can suggest is if you are growing even one Canna in a pot make it big, big. big. I had to break one of my pots to get it out. I had planted two in a 22" pot.
Stuttgart has small bulbs so you might be able to get away with two in a pot. But I planted Tropicanna and Intrigue together and could not get them out of the pot at the end of summer.
In these topics I have posted some examples of how I use my Cannas and mixing them with other plants for the pots.
The thread "My process" in
Containers forum
The thread "Cannas" in
Tropicals forum
