My Knockout Roses Were Blooming, but Have Quit
My knockout roses were blooming, but have quit. Do I need to fertilize them?
If the temps are in the high 90's to 100's where you are the rosebushes could be just taking a break to gain strength back. Heat stress will do this. Sometimes they do take a break between bloom cycles to regain strength. If you have not fertilized them at all or it has been a month or more, then yes fertilize them now. Make sure the soils moisture is good before and after feeding them as well.
Stan the Roseman