Hyssop Blue (35 ratings) Plants Available Spring, Summer And Autumn 9cm Pot £1.99 Add Delivery Slot: [Choose]Late Summer Late July - August Quantity: at £1.99 each Hardy perennial, Ht. 80 cm. Dense spikes of small dark blue flowers in summer. Small narrow lance shaped aromatic green leaves. Culinary, use small amounts with fatty fish and meat.