Anise hyssop (Agastache foeniculum) is a native of North America. Hybrid varieties were created and took the horticultural world by storm in 2004. Anise hyssop is a popular choice as part of a low-water, mixed border. The plant is 4 feet tall and 2 feet wide, with blue-violet flower spikes adding another foot in height. Flowers bloom in late spring and dead-heading (removing spent flowers) encourages repeat blooming through the end of summer. The strong anise flavor of its leaves makes it deer-resistant. Humans do enjoy eating the plant, so feel free to use the flowers in salads and the young leaves as garnishes.
Planting and Culture
Plant the anise hyssop in fall, as with most perennials, to give its roots a chance to settle and grow before the heat of the summer.
Get your anise hyssop off to a good start by choosing a sunny planting site. It will tolerate part-shade but thrives in the sun.
Dig a hole with your shovel, deeper and wider than the root ball of the anise hyssop.
Put the dirt from the hole on a piece of burlap or in a wheelbarrow. Add compost to the dirt to create the well-drained soil that anise hyssop needs. With your shovel, mix in 1 part compost to 3 parts dirt.
Refill the hole with the soil mixture. Scoop out enough room for the anise hyssop to sit firmly in the soil and have the top of its root ball at ground level. Pack the soil around the root ball.
Water the anise hyssop well with your hose. Press the damp soil firmly around the plant. Add a 2-inch layer of mulch over the planting hole.
Water regularly the first season. Anise hyssop will tolerate low water after the first year, but always prefers average water from rain or irrigation.
Analyze your climate to determine when to trim back the stems of your anise hyssop.
In a mild winter climate, like USDA zone 9, use your pruners and cut the woody growth back in late fall for a more compact plant shape the following year.
Delay pruning of your anise hyssop if you live in a cold climate. Provide additional winter protection to your plant and do not disturb the leafless stems on the plant until spring. Cut back the stems with your pruners to 6 inches above the ground in early spring.