Ageratum houstonianum is a herbaceous perennial. They usually treat it as an annual in most gardens. Ageratum in Greek means long-lived. It is also called the Mexican Paintbrush, Flossflower, BlueMink, Blueweed, or Pussyfoot. It is a very popular plant in beddings and borders in Southern California. Ageratum houstonianum is native to Central America, in particular Mexico, Guatemala, and Belize. It is part of the Asteraceae family of plants.
Mexican Paintbrush has a long flowering period. It flowers from May to November. It has a unique color that complements the pinks, reds, and yellows flowers, perhaps that makes it a popular flower to mix in borders. The flowers are violet-blue in color, they grow in dense corymbs. Ageratum houstonianum grows from 6 to 24in or 15 to 60cm.
How to grow Ageratum houstonianum:
Grow Ageratum houstonianum in the sun. Plant it in moist, humus-rich soil but well-drained. It does not like to dry out but it needs to be well-drained. It does tolerate some shade.
Ageratum houstonianum or Mexican Paintbrush is toxic to grazing animals as it contains pyrrolizidine alkaloids that cause liver damage. It attracts butterflies but it is deer and rabbit resistant. Ageratum houstonianum is easy growing and you can propagate it from seed. You can deadhead the flowers to keep them tidy but not as critical as it blooms for a long period.