Ageratum
Ageratum, or "floss flower" is such a little workhorse that nearly every garden should have some. This annual is an easy-to-grow, old-fashioned favorite that produces a steady show of colorful powder-puff-like flowers from late spring through frost. It's also rarely bothered by pests, so you count on it to look good. Plus, it provides some of the truest blues you can find in flowers.