Q.half of a rose quit growing
When we moved into this house, we acquired 4 beautiful rose trees. One of them has quit growing on 1/2 of the tree trunk? The other side still grows, slowly, and makes roses.
Grafter should have been grafted.....
Tree roses are grafted roses. The rosebush grafter onto the main trunk looks to be dieing. I recommend giving the rose tree some water that has a product called Super Thrive in it. Do this the next 4 to 5 times it needs watering. If you live in a warm climate area, you could also mix some root stimulator into the same water each time. That is about all you can do, the rest is up to the tree rose. Here is an article link for you to check out and read too: https://www.gardeningknowhow.com/ornamental/flowers/roses/learn-more-about-tree-roses.htm
