It sounds like the rosebush may be in a pot that has become too small and it is getting root bound in that current pot. Or perhaps the pot that it is in does not have drainage holes and there is some root rot going on. Either way, the rosebush likely needs to be transplanted either to a bigger pot or to a nice sunny spot out in the gardens. Once removed from the old pot, check the root system and see if it has begun to grow in the shape of the pot it was in. If so, gently pull the roots out of that shape as best you can prior to re-planting it. If it is very tight, another words truly root bound, it may not survive. In such a case you will need to be a bit more aggressive about pulling the roots out of their current shape and state. Once Transplanted, water the rosebush well with some water that has both a root stimulator and a product called Super Thrive mixed into the same water. Water the rosebush with this mix, freshly mixed up, each time she needs watering. Be sure the rosebush is getting plenty of good sun exposure.
