Yarrow
Propagation of Yarrow is by division and cuttings but it also spreads via seed and roots and grows up to 3 feet tall. Prone to mildew in hot, dry conditions. The white flower version is the medicinal herb but there are many colors of ornamental yarrow which do not contain the medicinal chemicals in high enough volume to be used as a medicine. Yarrow is a beneficial insect attractant plant (ladybugs and parasitic wasps).