It is not unusual for roses to "change color." A minor change occurs when cooler weather intensifies pink-to-red shades, or age and hot weather fade them. The change of the color may due to the fact many roses are grafted, so the branches are one variety and the lower root system is a hardier rose. f those lower roots sprout branches, they may appear different in shap, leaf size and flower color. The third change happens when one branch actually has a mutation affecting blossom color. Many of colors started as a single odd branch, called a sport, such as the branch of pale pink roses on a Red Knock Out rose that became a new variety, Knock Out ‘Blushing’ rose when many buds from the branch were grafted onto other rootstocks.