If the buds are small in relation to the square footage of the healthy foliage, and if the roots at the edge of the root ball are robust, you should have no problems. If the plant is small, I'd definitely cut the flower heads off.

A lot of your success will depend on temperatures, including night temps, and site preparation.

Thank you for your reply. The foliage probably spans about 10" and they seemed pretty pot-bound when I put them in the ground. I think I'll let the flowers be for a while, and I'll aggressively dead-head and keep on top of the watering until frost. Site prep included about 1/2" of homemade compost and a dusting of organic fertilizer in the top 4" of soil, and a couple of handfuls of compost and a tablespoon of fertilizer mixed into the bottom of the hole. A couple of inches of pine bark mulch.