A stalk will not get any taller after it puts out a bloom. However, thats not to say that future stalks will not get higher than 30 inches, it depends on the type of canna and how much sun, heat, water, etc it receives. I wouldn't think that the same canna would get as tall in Wisconsin as it would in Florida, but I can't say I've done or read anything to actually back that up.

So John, I should cross my fingers for a taller next stalk? Maybe I'll try to give them some extra water as well. Never having grown Cannas, or any tuber, I just don't know what to expect from my mystery plants. From the look of the buds, I'm guessing they'll be red. Thanks for the info, and the lightning speed response! I just love GardenWeb!

Extra water and maybe throw in some nitrogen couldn't hurt. Did any buds open up any today to see a color?

If you want tall cannas, just buy a named variety that grows tall.If you have a dwarf variety, it will never get to 5 or 6 feet.

It has been my experience that location has a lot to do with how the cannas grow. When I plant cannas along the road they get get to at most 4 feet and don't always bloom. Cannas on the south side of the house get to 5 or 6 feet and bloom. And in this one magical spot on the NW side of the house they get to 7 or 8 feet. This is all one variety from one original clump. The 8 foot tall ones are monsterous with 2.5'x 1' leaves and they bloom forever the flower spike never seems to stop branching. I wish I knew what caused them to do so well in that one spot. Also the monsterous cannas continue to send up new shoots throughout the year and everywhere else they send up shoots only in the spring and that is is until frost.