'Black Adder' giant hyssop is a hybrid cultivar cross between A. rugosa and A. foeniculum in the mint family (Lamiaceae). This plant grows 2-3 feet tall and wide in well-drained soil in full sun to light shade. Good drainage is essential as they will not survive a winter in wet clay soils. They are drought tolerant once established. Use a container or raised bed if needed to provide better drainage. The dense spikes of reddish-purple flowers will add a vertical accent to the garden and attract bees, butterflies and hummingbirds. Deadhead to prolong blooming. The leaves are aromatic and have a mint smell when crushed. Use this plant in the border, in groups or in naturalized areas. Use in a butterflygarden, pollinator garden or rock garden. Problems : Crown rot can occur in wet soils. No significant problems. Watch for Spider mites, thrips, aphids, whitefly, and slugs. More information on Agastache .
Curated pairwise relationships between this plant and others in the library — who feeds
whom, who competes, who confuses the pests. Green reads as a good pairing, red as one to avoid.
No curated interactions recorded for this species yet.
Also noted by NC State
Related species the NC State Plant Toolbox flags for this plant — look-alikes to tell
apart, and plants that play a similar role in a planting. Ones we carry in the library are linked.