Various cultivars and species allow you to have a yarrow that's anywhere from a few inches to several feet tall. Give this plant full sun and place the taller types two feet apart. Propagate by stem cuttings in midsummer or by division every few years in the spring or fall. Another great perennial for hot, dry and poor-soil conditions, the coneflower also handles light shade. Besides the common rosy-hued species, cultivars offer a few other shades including white.
Space plants two feet apart.
Zones 3 to 9. Give perennials the site and soil they prefer the most, then be patient, says Kolls.