Anise hyssop can be propagated a few ways, the most popular of which is division. The plant develops underground rhizomes, which are stem-like structures that have the ability to produce new growth. These rhizome clumps can be dug up, divided, and re-planted to increase the number of anise hyssop plants in your garden. This process is best performed in the spring for optimal growth. Like most herbs, anise hyssop can also be propagated through cuttings.