Hydrangea macrophylla 'Kompeito' STAR GAZER

Common Name: bigleaf hydrangea 
Type: Deciduous shrub
Family: Hydrangeaceae
Zone: 6 to 9
Height: 3.00 to 4.00 feet
Spread: 3.00 to 5.00 feet
Bloom Time: June to October
Bloom Description: Blue or pink with white edges
Sun: Part shade
Water: Medium
Maintenance: Medium
Suggested Use: Hedge
Flower: Showy, Good Cut, Good Dried

Culture

Best grown in rich, medium moisture, well-drained soils in part shade. Tolerates full sun only if grown in consistently moist soils. Soil pH affects the flower color of most cultivars except white (blue in highly acidic soils and lilac to pink in slightly acidic to alkaline soils). Add aluminum sulfate to the soil to make the flowers bluer or add lime to the soil to make the flowers pinker. Begin soil treatments well in advance of flowering, as in late autumn or early spring. Plants generally need little pruning. If needed, prune immediately after flowering by cutting back flowering stems to a pair of healthy buds. Prune out weak or winter-damaged stems in late winter/early spring. Best to mulch plants year-round with 3" of shredded bark, peat or compost. Winter hardy to USDA Zone 6. For added protection, however, plants grown in USDA Zone 5 should be sited in sheltered locations and given additional winter protection, as needed, for the purposes of minimizing the risk of loss of significant numbers of flower buds or possible die-back to the ground in an extremely harsh winter. A burlap wrap of stems or circle of chicken wire filled with leaves or straw to 8-12" are time-consuming and visually unattractive landscape options, but can be effective. Regardless of protective measures taken, most bigleaf hydrangeas simply will not bloom (or will bloom poorly) in some years because of a variety of winter occurrences beyond the control of the gardener (e.g. low temperatures, sudden wide temperature fluctuations, icy conditions, late frosts). Some newer cultivars have been selected that flower on both old and new wood. Their pruning and flowering can differ from that of the species.

Hydrangea macrophylla STAR GAZER blooms on both old and new growth and reportedly has better winter hardiness than many of the other H. macrophylla cultivars in commerce today. Even if old growth buds are damaged in winter, plants should still flower in summer on new growth.

Noteworthy Characteristics

Hydrangea macrophylla, commonly called big leaf hydrangea, is a deciduous shrub with a rounded habit that, in the St. Louis area, typically grows 3-6’ tall and as wide unless damaged by harsh winters or pruned smaller. It generally features serrate, obovate to elliptic, dark green leaves (4-8” long) and large clusters of long-blooming summer flowers in either lacecap form (flattened flower clusters of small fertile florets with scattered showy sterile florets often forming a marginal ring) or mophead form (globose flower clusters of mostly showy sterile florets).

The genus name Hydrangea comes from hydor meaning "water" and aggeion meaning "vessel", in reference to the cup-like capsular fruit.

Specific epithet comes from the Greek words makros meaning large and phyllon meaning leaf in reference to plant leaves.

'Kompeito' (trade name of STAR GAZER) is a compact lacecap cultivar that typically grows to 3-4' tall and to 3-5' wide. It is part of the DOUBLE DELIGHTS SERIES from Ball Ornamentals. It typically blooms on old wood in late spring with repeat bloom on new wood from summer often into fall if spent flowers are regularly deadheaded. Each lacecap inflorescence features a mass of small fertile flowers surrounded by large double flowers on long petioles. It is a rebloomer that produces flowers in spring on old wood (flower buds are produced the previous fall and overwintered) and a repeat bloom of flowers from summer into fall on new wood. If old growth buds do not survive winter, plants will still bloom summer to fall, albeit less floriferously, on the new growth. Spent flowers should be regularly deadheaded. Flower color ranges from blue with white picotee edges (acidic soil) to pink with white picotee edges (alkaline soil). Leaves (to 6" long) are glossy green. U. S. Plant Patent PP20,998 was issued on May 18, 2010.

Problems

Some susceptibility to bud blight, bacterial wilt, leaf spot and mildew. Aphids are occasional visitors.

Uses

Group or mass in the shrub border. Also a good specimen or accent for foundations and other locations near homes or patios. Hedge. Containers.