Buy hyssop (syn. Black Adder) Agastache 'Blackadder'

Agastache 'Blackadder'

hyssop (syn. Black Adder)

Hyssops are great for adding height to a border, with whorls of long-lasting, tiny flowers arranged like a bottlebrush, and pointed, aromatic fresh green leaves that are attractive to butterflies. They are short-lived though, and may need replacing every few years, especially after a cold or wet winter. 'Blackadder' has smoky, violet flowers on long spires from July to October. Try it as part of a Mediterranean scheme or in a sunny, well-drained border among ornamental grasses.

How to care for Agastache Blackadder:

Plant in a well-prepared bed, lightly conditioned with well-rotted compost or manure. Keep cutting the old stems out to encourage repeat flowers through the summer. Once the flowering period is over, resist the temptation to cut back the faded flower-stems until early spring, as they provide interest in the winter months. Once established, lift and divide congested clumps in spring. Protect roots during the winter with a thick layer of organic mulch around the root zone.

Flowering period:

Eventual height:

0.9m

Eventual spread:

0.4m

Position:

Full sun

Rate of growth:

Average

Soil:

Moderately fertile, moist, well-drained soil

Hardiness:

Borderline hardy (will need protection in winter in colder areas)

This perennial dies back to below ground level each year in autumn, then fresh new growth appears again in spring.