Looks like Campanula 'Blue Clips', and yes, deadhead it to encourage more blooms.

I believe it is balloon flower ' Platycodon '.
I have it in white , pink , lavender and what I call blue .

Here is a link that might be useful: http://www.bhg.com/gardening/plant-dictionary/perennial/balloon-flower/

This post was edited by Sammywillt on Fri, Aug 9, 13 at 15:50

Definitely Platycodon. The ones they sell here are artificially dwarfed (with hormones). Next year it may grow twice or "thrice" that tall.

OMG, I am mortified. I am always mixing them up: platycodon and campanula. Sorry!

The photo is definitely Platycodon grandiflora/Balloon flower. It will bloom on schedule in August (in Zone 5 or 6) even if you whack it down in late May/early June to half its size. Just chop it back with pruning shears to control height. It'll "bleed" a white sap but pruning won't slow or impede the flowering.

I've grown it from seed via winter sowing and the plants are all blooming profusely this year. It's one of those "plant it & forget it" perennials aside from whacking it down early in the season to keep it from growing too tall.

Grief, I HATE that whole dwarfing thing going on - bad enough that plants are selectively bred for innate height restriction but mucking about with gibberellin inhibitors to keep plants small (for a season) really infuriates me beyond reason. Why? The plants invariable retain large flowers on a stunted looking plant (the travesty campanula lactiflora 'pouffe' is one that makes me desire to crush it under my heels). I am always on the lookout for tall graceful perennials but will accept that people like little cushiony ones too (I like the little alpine pinks and armeria, androsace, aubretia, as much as anyone) but a plant such as platycodon is disusting as a squat little thing when, left to its own devices, it will gain a height of 70cm (2.5feet), swaying gently while still remaining utterly self-supporting - what could there be to not like about that?

campanula - I cut back Platycodon grandiflora because if left to its own devices it grows 5+ ft. tall where I am and flops over on the ground. It pleases me more in my garden beds to have plants grow upright without garden supports rather than sprawl on the ground. Given the fact they're not inhibited from blooming when given a haircut early in the season, I don't consider it officious to take steps that ensure they please my eye in my garden beds each year. They're one of my favorite perennials. If they normally grew to the 70cm (2.5 feet) you mentioned above, I'd be able to delete the chore of cutting them back from my Spring garden To Do list. Since they normally grow to twice that height or more in my zone, whacking them will be my solution. I regret that you're not pleased with my organic solution to a garden problem.

now now- GWeed, I don't think I was referring to cutting back perennials to keep them smaller, but to the distinctly non-organic fiddling about with growth hormones to keep plants smaller, against their natural inclinations to stretch....(a practice widely done on platycodon but most heinously, on chrysanthemums and osteospermums).......alongside the deliberate breeding of tall plants to turn them into dumpy (and pitiful) shadows of themselves (the aforementioned campanula). The Chelsea Chop (as we call it here) is widely practiced (and I am certain that I would be doing a bit of whacking too, if my balloon flowers grew as tall as me).

campanula - Thanks--I very much appreciate the clarification. I didn't realize & will confess my ignorance of the extreme tactics being undertaken to control plant growth/size habits and am equally appalled at the lengths growers will reach to increase sales. I learned organic gardening at my grandfather's knee 60+ years ago and have continued to adhere to his precepts my entire life. I'm proud that both my children continue the commitment & tradition. In my garden beds, whacking is okay; chemicals are uninvited.

Sorry if I offended you but appreciate you responding.