I purchased 10 knockout roses nearly 2 years ago. Planted about 20′ in from a narrow 2 lane private road (very light traffic). I created a bed used landscape fabric, and small white marble stones as a mulch bordered by decorative landscape blocks in front with a white picket fence behind. I fertilized them once with a fertilizer designed for roses. I would expect by now (?) the bushes would have filled in nicely. Wrong….they are alive but they haven’t grown much larger than the day I bought them. What do you suggest? Thank you.
When rosebushes are not taking off, the first thing I think of is that there may be something not right about their soils home. I would dig out a soils sample in 3 to 4 places along the rose bed and have the soils tested. Let them know the problems you are having so they can look specifically for things that may be causing a problem. soils pH can be a big problem as the pH not being right can lock up available nutrients in the soils so that the root system just cannot take them up and use them properly.
Here are some links to articles that should be of interest to you: