You could transplant the roses, but this is really not helpful for your son. You may consider my response a bit extreme, but I work with kindergarten through second grade students. I have witnessed some pretty sad things that have affected my opinions.
Learning limits and about the world is so very, very important. Learning them at home with parental support is preferable to learning limits at school. Little helpful lessons about roses, house plants, breakables in and about the house can translate in many, many other ways.
Your child will be soooo much more ready for the world if he gets to grow up learning the joys of gardening and playing in the dirt which include but are not limited to early math concepts, natural science, ecology, biology, etc. I would encourage experiential learning which would include roses and a vast array of every day life experiences inside and outside the home and yard.
Sorry, as a teacher, I feel very sad for those students that have been overly protected. They often struggle socially not having learned limits and boundaries even though their parents had the very best intentions and only wanted to protect their child. We all love our children, but we also have to have a vision for the child as a student, teenager and adult that we hope they will be. I would highly recommend sharing a book study on Love and Logic with your wife. If she feels this away about roses it makes me feel sad and worried for the future.