The unusual, fully double flowers of cactus dahlias have pointed tubular petals that give them a spectacular starburst look. The flowers, which come in breathtaking colour combinations, look stunning growing in small groups or as a specimen. Blooms have no visible central disc. Owing to the unique flower form, cactus dahlias have the ability to withstand inclement weather, including strong winds and heavy downpours. Semi-cactus dahlias also have double blooms with no visible central disc. Their pointed, tubular petals have a broader base at the bottom than cactus types.