This is a common occurence for rhododendrons grown in pots with a peat based planting medium. What you did already is exactly right - tearing off pieces often happens and will do no harm. If the root ball is very dense, slicing it in several places along the perimeter and across the bottom with a sharp knife is also a good idea. A hand cutivator with sharp prongs and/or a forceful stream of water from a hose can also be used to loosen the roots. Soak in water for a half an hour or so before replanting. Then - and this is important - water when needed with just a very slow trickle at the base of the plant for the rest of the summer and fall. You want to keep the root ball moist without saturating the surrounding soil. You might also want to check your planting area. You want a wide shallow area amended with lots of organic matter - if there is an abrupt transition between the planting medium around the roots and the native soil, it's very difficult for the rhododendron to extend its roots.

If this forum had a like button, you'd have one DownEaster. You just did everyone a great service with this on the money post as to planting rhodies.

The only thing I'd add is that one's siting of the rhody should always be one that avoids a lot of afternoon sun (the hottest part of the day).

Happy 4th everyone.