What can I fertilize my roses with to help create thicker, stronger branches? I have clayish soil that I have been working to break down. The pH is between 7 and 8. Many of the leaves on my roses are turning yellow. I have about 45 tea rose plants. The first bloom was good but now many of the roses have yellow leaves (didn't show black spots before turning yellow and the branches are thin and weak).
The pH is on the high side but not bad. Optimum for rosebushes is 6.5. It could be that they are heat stressed, have too much water issues or the pH level is locking up some of the nutrients that the rosebushes need. Here are some links to articles on these subjects that should be helpful to you, please check them out: