Plant container roses during any part of the growing season.
Before you plant a container-grown rose, gradually reduce its water (a process called hardening off) for a week. But on the day you plant, make sure the container soil (and the soil in the planting hole) is moist. Reducing its water beforehand will help prepare the rose for the transplant, and watering at planting time will help keep the root ball together and reduce stress caused by the surrounding dry ground soil absorbing moisture away from the roots.
1. Remove the bottom: Lay the container on its side. Cut off the base of the compressed fiber pot with a small saw. Try not to damage any of the roots.
2. Place in hole: Place the root ball in a hole that has been dug out to about 2 feet wide and 2 feet deep. Make sure the bud union is at the proper level.
3. Remove the container: Remove the rest of the compressed fiber pot as if you were peeling an orange. Don't worry if some roots show on the surface of the root ball.
4. Fill in with soil: Fill the remaining space with a good quality potting soil or amended soil. Water, allow to settle, and finish off with more potting soil.