Q: We have fifteen carpet roses which have bloomed dark red for six years. This year three of them have pink blooms. All were pruned the same in the fall and fertilized the same in the spring. Why did the color change?

A: On grafted roses, the new colors might come from sprouts below the graft union. However, carpet roses are typically not grafted; they are propagated via cuttings. My guess is that the three are reverting to the color of the pink-blooming parent rose from which yours were once bred. It seems unusual that three plants would revert at the same time but this is my best speculation. If red blooms appear on the newly pink plants, prune out the pink flower stems and let the red-blooming stems take over once again.