Ageratum, Hardy AgeratumNative Pollinator Plant. The fuzzy blue flowers of hardy ageratum top attractive red stems in late summer and early fall. Easy to grow, it naturalizes readily and works well as a filler or groundcover planting. Its brilliant blue flowers make a unique and long lasting cut flower. In warmer zones and loose soils, plan for quite a bit of spreading. Color: Purple Shades Height: 2 3 Feet Spread: 2 3 Feet Zone: 4 8 Flowers attract bees, butterflies, and