After growing most of my roses in containers for about 10 years, I have finally figured something out. The bare root roses I have planted in containers have become much better bushes than the roses I purchased already in pots and transplanted. I think I know why. When roses are commercially potted for sale, the roots of bare root roses are trimmed so they will fit in the pot. So the rose may not have all the roots it needs to reach its intended potential.
When a rose bush has been grown in a container for as long as 7 to 10 years and it is worth keeping, it’s time to carefully repot it. Keep the root system as intact as possible. You can reuse the container but plant the bush with all new soil mix. This process will reboot the life of the bush.