This hyssop is dependably hardy to -5C, and it produces its fattened spikes of deep violet-blue flowers over a long period from midsummer. These not only look great, but they will also help attract lots of beneficial insects, so it's perfect for a wildlife-friendly garden, while the rich green foliage, which releases its licorice-like aroma when gently bruised.
Position: full sun
Soil: well-drained, fertile soil
Flowering period: July to October
Height and Spread: 0.6m, 0.45m