'Black Adder' Anise Hyssop has prolific deep blue bottlebrush flowers from mid summer to fall. 'Black Adder' is a cross between A. rugosa and A. foeniculum. Compact habit and excellent hardiness make this a very exciting Agastache. Dry site tolerant with deliciously fragrant foliage. Good drainage is essential for these plants as they will not survive a winter in wet clay soils. They are drought tolerant once established. From Coen Jansen.