Can I prune Anise Hyssop to encourage growth?


Anise hyssop. Last years plant outside got very tall (approx. 5ft) and had long lasting flowers, however it was very spindly/sparse. It didn’t spread as I’d hoped this spring. Can I prune this now like an herb to encourage bushier growth (like mint or basil) or does this not work for this plant? 


Liz Stanley, Horticulture Community Education Assistant

Anise hyssop is a short-lived perennial. It doesn’t spread from rhizomes as aggressively as other plants in the mint family (especially mint). It also reproduces from seed, so if you’d like more plants, let the flower heads stay on, ripen, and fall to the ground in the winter.

If the plant was spindly, it may have been in too much shade (though it will grow in full sun to part shade). It may also have suffered during last year’s drought or from a problem with soil pH or nutrients. Here’s how to test your soil.

If the flower buds have not yet formed, it’s not too late to top it carefully so that the plant develops a few more branches. It’s also not too late to grow some in the same area from seed. Seeds need light to germinate, so barely cover them with soil. They should germinate in 1-4 weeks if the seeds have been stratified (chilled) adequately. These new plants may not bloom this year but will provide more plants and flowers for next season.

More about Agastache foeniculum in this Anise Hyssop fact sheet from the University of Wisconsin.