Best grown in rich, medium moisture, well-drained soils in part shade. Tolerates full sun only if grown with consistently moist soils. Soil pH affects the flower color of this species in somewhat the same manner as it does with H. macrophylla, namely, bluish in highly acidic soils and lilac to pink in slightly acidic to alkaline soils. Bloom occurs on old wood. Little pruning is needed. Prune after flowering by cutting back flowering stems to a pair of healthy buds. Prune out weak or winter-damaged stems in early spring. Winter hardy to USDA Zone 6. Can be grown in USDA Zone 5 with protection (e.g., mulch and burlap wrap), but may lose significant numbers of flower buds or die to the ground in harsh winters, thus respectively impairing or totally destroying the bloom for the coming year.
Hydrangea serrata is similar to big leaf hydrangea (H. macrophylla) except it is a smaller more compact shrub with smaller flowers and leaves. It was formerly listed and sold as Hydrangea macrophylla var. serrata. It is native to moist woodland mountain valleys in Japan. It is a deciduous shrub with a rounded habit that, in the St. Louis area, typically grows 2-4’ tall and as wide unless damaged by harsh winters or pruned smaller. It generally features toothed, ovate, dull green leaves (to 6” long) and long-blooming summer flowers. Flowers appear in flattened clusters in lacecap form, with the scattered showy sterile florets forming an outer marginal ring around the tiny fertile florets. Plants are grown in alkaline soils for pink florets or in acidic soils for blue florets. Leaves of Hydrangea serrata can be used to make a sweet tea, hence the sometimes used common name of tea of heaven for this shrub.
Genus name comes from hydor meaning water and aggeion meaning vessel in reference to the cup-like capsular fruit.
Specific epithet is in reference to the serrated leaves.
'Golden Sunlight' is, as the name suggests, a golden-leaved cultivar. It typically grows to 2-3' tall and as wide. Leaves emerge bright lemon yellow in spring, gradually mature to light green by flowering time and then acquire burgundy tints by fall. It is a lacecap-type featuring pink florets edged with white. Plant patent applied for (PPAF).
No serious insect or disease problems. Some susceptibility to bud blight, bacterial wilt, leaf spot and mildew. Aphids are occasional visitors. Winter hardiness in the St. Louis area can be a significant problem.
Group or mass in a sheltered location in the shrub border. Also a good specimen or accent for protected locations near homes or patios.