Vary heights and repeat a simple color palette to bring individual vases together.
Vary the silhouettes
Pair a tall, slender vase with a rounded one and a smaller vessel. Place them slightly off-center rather than in a straight line.
Leave room between objects
A shared color or finish connects different shapes. Cream, sage and terracotta work well together. Leave breathing room between the vases; one branch may be all the arrangement needs.