Space according to ultimate size. Choose a good garden soil, high in organic matter that will help keep ample moisture available to the roots. The location should be sunny or partly shaded, the latter being preferable in dry areas.
If the pH of your soil is too high (alkaline), it can be reduced (made more acidic) by the addition of one tablespoon or more of Aluminum Sulfate per plant – this will make your flowers a deeper blue.
An annual mulch of compost is beneficial. In very cold or exposed locations, “hill” up the soil and mulch the base of the plant with pine needles or leaves. Most species require little pruning except the removal of dead flower heads after blooming or in early spring.
For H. arborescens, prune the previous year’s flowering wood to the ground in early spring. For H. macrophylla (H. hortensis) and H. serrata, thin out two- or threeyear- old flowering shoots at ground level to promote vigorous new growth. H.petiolaris should be pruned only for aesthetics.