Have two in our garden, which have been there for more than five years.

Today, they've already started flowering and tallest stem on one is 38 inches (number of stems been reduced this year) and on the other 46 inches (number of stems not been reduced this year).

As someone posted, much of this is likely variability associated with growing from seed stains. Then there's factors such as when the plants were planted.

Find balloon flowers to be one of the best perennials for mixed perennial gardening here, for reasons such as hardiness, compactness (at ground level. I do stake them) and longevity.

Personally, I like the blue ones best. Can get a better show of pink and white flower colour from some other well behaved summer perennials. As said, like the double 'Hakone Blue' best.

Have moved a few, but, as a generalization, the deeper rooted perennials (e.g. balloon flowers) are the ones that don't like being moved.

Personally, I like varying heights in mixed perennial beds. For me, the idea of having only dwarf and other short cultivars brings bedded annuals to mind.

Thanks, Sunny. I'll keep them toward the back then. I was about to move them in front of a smallish (22") daylily, 'Fond Hope.' I'll definitely put Fond Hope in front!

How wide do yours get? I may need to separate them more than the tag said.