Would have been best to do it in autumn, but if you must do it now, dig up the clump carefully, trying as far as possible to keep all roots intact and with a solid, large lump of soil around it, and transport the whole thing to its new position. Make sure the hole you dig in its new position is large enough to take the whole thing, and don't bury any lower or higher than it is currently. Water thoroughly. This only works, though, if you have heavy soil, it's impossible to keep a solid lump of soil around them if they're growing in light soil.

Agree entirely with Bamboo. You might find it won't flower for a year or two after flowering. I moved several from a customers garden about 3 years ago. Roughly a 30% flowered the following year another 60% after 2 years and and the remainder in year year 3