Hyssop (Hyssopus officinalis) is a perennial flowering plant that thrives in USDA Hardiness Zones 3 to 9. Planted in full sun, hyssop grows from 20 to 35 inches in height with a 16-inch spread and blooms from July to September. Hyssop flowers are used to scent potpourri and perfumes and, because they are edible, incorporated into salads, soups and teas. Hyssop is almost maintenance-free once it becomes established.
Prune the entire hyssop shrub back to 1 foot tall in early spring.
Cut off faded and dead flowerheads during the growing season.
Trim the hyssop again after flowering. This should be a lighter pruning than the early spring pruning and is performed to keep the plant to the size and shape you desire. This pruning will also encourage the hyssop to grow thicker.
Clean the planting bed of all pruning detritus. Foliage and flowers left on the soil become breeding grounds for garden pests.