I've moved them at various times of the year. If you want it done now, do it, but you will probably lose bloom and it may have some difficulty if the weather gets hot and/or windy. Ideally early fall works well for me if I mulch it to keep soil warm later.

Thanks Ken and NhBabs, will do late August then.. might as well enjoy the fragrance first :)

Well the best time to move any plant is when it is dormant. So that would be early spring at best, and some time in fall as second best, the plant needing to prepare for winter. So spring is best. If that's what you're asking.

+om

You may find that fall is best here in New England. Where I am in central NH, in spring we go from frozen ground to 80 degrees in about 4 or 5 weeks at most, and often the soil is still quite cold when the air is hot. Much shorter springs than in my midwestern childhood, and so there's not much time for a plant to settle in before the stresses of summer and long hours of sun. I find I am most successful transplanting in fall which tends to last longer here with warmer soil and cooler air temperatures (late September to early October). Just be sure to mulch well. Depending on how well the plant settles in, you may find you lose the flowers next spring regardless of whether you do a fall or spring transplant.

Be prepared for some serious digging. When I dug up one of our old ones, I swear the roots were halfway to China.