Most roses should be cut back or pruned in the spring. The perfect time to prune is when the buds on the stems start to swell and turn reddish in color. In most climates, this event normally coincides with the time when the forsythia bushes start to bloom.
An additional pruning is needed in the summer for some varieties of roses that are grown in the warmer zones and are characterized by vigorous growth. Pruning in the summer helps maintain the look and shape of the rose bush, and it encourages repeat flower growth. The rose bush should be pruned to approximately half its size to maintain its round shape.