Just when it looks like summer’s heat has convinced every flower in my garden to close up shop, I am never surprised to see ageratum, or blue mistflower, in full bloom. This little annual produces soft blue flowers from spring through the first hard freeze, so I can rely on the staying power of its color in my borders. In summer ageratum looks terrific with white petunias, lamb’s ear and chartreuse creeping Jenny ‘Aurea’. Yet it is equally appealing mixed with autumn favorites such as asters, golden patrinia and goldenrod.