Troubleshooting
Anise hyssop problems — and how to fix them
Anise hyssop (Agastache foeniculum) is generally forgiving once you match its basics, but a few issues come up again and again. Here is what each one looks like, why it happens, and the fix.
Self-seeds prolifically
Deadhead spikes before seed sets.
Powdery mildew
Late summer; improve air flow.
Crown rot in wet winters
Needs sharp drainage.
Floppy stems
Cut back by a third in early summer for bushier growth.
Decline after 3-4 years
Replant from seed or division.
Prevent anise hyssop problems before they start
Most anise hyssop issues are care-mismatch, not bad luck. Dial in the basics:
Anise hyssop problems — FAQ
Why is my anise hyssop self-seeds prolifically?
Deadhead spikes before seed sets.
Why is my anise hyssop powdery mildew?
Late summer; improve air flow.
Why is my anise hyssop crown rot in wet winters?
Needs sharp drainage.
Why is my anise hyssop floppy stems?
Cut back by a third in early summer for bushier growth.
Why is my anise hyssop decline after 3-4 years?
Replant from seed or division.