Hydrangea
Hydrangea species (HYDRANGEACEAE, formerly SAXIFRAGACEAE)
Planting and Growing Hydrangea
You’ll find everything you need to know to plant and grow hydrangea in the accompanying table’s tabs:
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- Flowers, foliage, seed pods, and seeds of hydrangea
- Growing conditions for hydrangea
- When and where to plant hydrangea
- How to plant hydrangea
- How to shape, prune and control growth of hydrangea
- Watering, fertilizing, and care of hydrangea
- Landscape uses of hydrangea
- Pest and disease control for hydrangea
Growing Hydrangea
Over 20 species of tall or climbing, bushy, deciduous or evergreen shrubs, 4–8 ft. (1.2–2.4 m) tall, with shiny, dark green, broad, oval, lobed or deeply toothed leaves, to 12 in. (30 cm) long.
Among the most popular and commonly cultivated hydrangea species are big-leaf hydrangea (Hydrangea macrophylla,) panicled hydrangea (Hydrangea paniculata), and smooth hydrangea (Hydrangea arborescens).
See also Oak-Leaved Hydrangea, Hydrangea quercifolia.
Hydrangea Planting and Care Guide
Flowers and Seeds
Abundant round or star-shaped, blue, lavender, pink, purple, white, sometimes sterile flowers, to 1 in. (25 mm) wide, in summer–early autumn, form mounding clusters, to 18 in. (45 cm) wide, with seed in autumn.
Best Climates
U.S.D.A. Plant Hardiness Zones 4–10. Most ground hardy, zones 6–10.
Soil Type and Fertility
Moist, well-drained, loose soil. Fertility: Rich. Add compost or leaf mold. 6.5–7.0 pH. For best blue flowers, add aluminum sulfate; reds and pinks, garden lime.
Where and How to Plant
Full sun to partial shade. Space 6–10 ft. (1.8–3 m) apart.
Proper Care
Moderate. Keep moist; allow soil surface to dry between waterings until established. Fertilize every 2 months spring–summer. Deadhead reblooming hydrangeas once their flower turn to green or brown, when two small buds first appear at the junction of the flower’s central stem to the branch. Leave the buds to grow and produce a second round of flowers in autumn. Prune severely in autumn or early spring. Propagate by cuttings, division, layering, seed.
About This Species
Good choice for borders, hedges, screens in cottage, woodland gardens. Cut and dry flower heads for wreaths and floral arrangements. Aphid and chlorosis, mildew susceptible.
Common Species of Hydrangea
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- Hydrangea anomala var. petiolaris, climbing hydrangea
- Hydrangea arborescens, smooth hydrangea
- Hydrangea aspera, Sargent hydrangea
- Hydrangea heteromalla, Bretschneider hydrangea
- Hydrangea macrophylla, big-leaved hydrangea
- Hydrangea paniculata, panicle hydrangea
- Hydrangea quercifolia, oak-leaved hydrangea
- Hydrangea serrata
About Hydrangea
The Hydrangea genus includes nearly 25 species of midsized, erect, climbing or branching, bushy deciduous shrubs.
They are native to both Americas and East Asia, are hardy, and do best in U.S.D.A. Plant Hardiness Zones 6–10, though a few are hardy to zone 4.
Hydrangeas are fast-growing shrubs. Most species are 4–8 ft. (1.2–2.4 m) tall. Use them as foundation or border plantings, as hedges, or as screens in full or filtered sun or in sites with partial shade.
They bear showy pom-pom-like clusters of round-petaled or star-shaped florets ranging in colors from white to blue, pink, and purple.
They bud in spring, bloom in summer, and have flowers that are either fertile or sterile, borne in diminutive lace caps, or in showy clusters.
Flower clusters of hydrangea frequently are cut and arranged fresh or dried as showy floral arrangements.
Most hydrangeas are susceptible to aphids and mildew when conditions are too cool and moist.
Prune them once their flowers fade in autumn, or in spring before growth begins.
Choose from among the most popular species of Hydrangea, listed above.
Planting and Caring for Hydrangea
The hydrangeas have long been prized for their showy, clustered flowers and for their glossy, rich-textured foliage.
Hydrangea flowers vary in color depending on the acid-alkaline balance of the soil in which the plant grows. Their flowers are more deeply colored in acidic conditions, and the plants may yellow with chlorosis if their soil turns too alkaline.
Their flowers are long-lasting. Flowers appear in summer, retaining all their charm even after they have dried.
Their many arching branches create graceful, full-bodied shrubs that complete shrub borders through the entire garden season.
Plant hydrangeas in a moist, well-drained, acidic soil mixed with rich organic humus. Apply an acid fertilizer every two months from early spring until the flowers begin to fade.
Hydrangeas grow best in locations with filtered sun or partial shade and should be protected from the sun in hot-summer climates.
They tolerate heavy prunings in autumn or spring, when they should be shaped to maintain their compact habit and dense foliage.
Use hydrangeas at the centers of beds, in shrub borders, or as understory plants in shade and woodland gardens.
They are good companions for acid-soil plants that bloom in early to midspring, providing annual and perennial flowers a background of rich foliage against which to show their flowers and flowering after azaleas, camellias, and rhododendrons have finished their seasonal bloom.
To dry hydrangea clusters while retaining their form, color, and charm, cut them at their peak bloom, strip their leaves, and hang them upside down in a warm, dry spot.
Some gardeners prefer to dry hydrangea flowers by packing their blossoms in silica gel, a dessicant that quickly removes their moisture. Dried hydrangea flowers provide beauty in floral arrangements year-round.