Hydrangea

Fundamental Facts

HARDINESS: Zones 4 to 9
PREFERRED SOIL pH: Slightly alkaline to slightly acid
PREFERRED SOIL TYPE: Rich, moist, well-drained
PREFERRED LIGHT: Sun to partial shade
ATTRIBUTES: Handsome deep green leaves; large clusters of white, pink, blue flowers
SEASON OF INTEREST: Early summer to fall
FAVORITES: H. macrophylla, H. quercifolia, H. arborescens, H. paniculata
QUIRKS: Flower color can change
GOOD NEIGHBORS: Azalea, mountain laurel, rhododendron
WHERE IT GROWS BEST: In fertile, moist, well-drained soil
POTENTIAL PROBLEMS: Soil pH above 7.0 can cause leaf yellowing
PRUNING: Prune plants right after flowering
CRITTER RESISTANCE: Excellent
SOURCE: Nursery plants
DIMENSIONS: 3-15 ft (1-4.6 m) tall and wide

Hydrangea in the Landscape

Adaptable and long-lived, hydrangeas are deciduous shrubs smothered under their immense heads of papery florets from summer till fall.The handsome flower clusters, excellent for cutting and drying, appear on the tips of upright stems clothed in deep green, sometimes variegated leaves.

Plant hydrangeas around house foundations or integrate them into flower beds. They are also stunning specimens in the lawn and make a colorful boundary border, mixing well with many other shrubs. Smaller cultivars are even suited to large pots.

Chameleon Flowers

The most common species is bigleaf hydrangea (H. macrophylla), which grows 4-6 ft (1.2-1.8 m)tall and is hardy to Zone 5. The flowers of mop-head, or hortensia, types produce big globes of star-shaped petals, while the lacecap types have flatter flowerheads with frilly blossoms in the center and larger florets around the edges.

Flower colors range from pink to blue but can be altered by changing soil acidity.The lower the pH, the deeper the blue. For blue flowers, apply aluminum sulfate or a commercial "bluing" compound. For pink flowers, add a high-phosphorus fertilizer or garden lime. Use any amendment according to package directions.

All in the Family

The smooth hydrangea (H. arborescens) is a North American native that is hardy to Zone 4 and produces white, snowball-like flower clusters that can reach up to 1 ft (0.3 m) in diameter. Another care-free native, the oakleaf hydrangea (H. quercifolia) has large conical white flowers that age to purple, and its lobed leaves turn yellow and red in fall. It reaches 8 ft (2.4 m) tall and wide and tolerates shade.

The peegee hydrangea (H. paniculata 'Grandiflora') reaches 15 ft (4.6) tall and spends most of the summer covered in dense clusters of creamy flowers that resemble cotton candy. Peegees prefer partial shade and fertile soil and are hardy to Zone 4.

Growing Hydrangea

Plant hydrangeas in spring or fall at the same depth at which they grew in the nursery pot. Keep the soil moist
the first growing season and water during dry spells thereafter. Add a 3 in (7.6 cm) layer of organic mulch to retain soil moisture. Shape the plant and remove any damaged or weak branches right after flowering by cutting stems back to a strong set of leaves. Prune old, woody stems to the ground every 2-3 years in late winter.