'Red Happiness' delivers some of the richest color in the Agastache genus — true red-burgundy spikes on a plant that is otherwise remarkably airy and fine-textured. The foliage is slender and fragrant, and the overall effect is of something wilder and more meadow-like than the boldness of the flower color would suggest. It grows to about 1 to 2.5 feet, which puts it near the front of a perennial border or butterfly garden where the long bloom season, from late spring until frost, gives it an outsized contribution to the planting.

Good drainage is essential and non-negotiable. Raised beds work well if the native soil is heavy; containers are another excellent option, especially on a patio where hummingbirds and bees can be observed at close range. Powdery mildew and leaf spot can appear in humid conditions but rarely compromise the plant's vigor. Deer resistance is reliable. Zones 5 to 8.