Oakleaf Hydrangea

(Hydrangeaceae - Hydrangea Family)

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• Form
  • medium-sized ornamental shrub
  • maturing at about 7' tall by 8' wide
  • radiating rounded growth habit
  • slow growth rate in youth, sometimes achieving a medium growth rate with establishment

• Culture
  • full sun to full shade
  • prefers moist, well-drained, rich, slightly acidic soils in full sun, but is tolerant of dry or wet sites, soils of average fertility, and neutral to slightly alkaline soils (the foliage may become slightly chlorotic in extremely alkaline soils, which can be remedied with an annual regimen of fertilization)
  • propagated by seeds, rooted stem cuttings, division of the young plant, or removal of rooted suckers
  • Hydrangea Family (some sources list Oakleaf Hydrangea under Saxifragaceae), with virtually no disease or pest problems
  • abundantly available in ball and burlap or container form (although sometimes sold out, due to high demand and slow growth rate)
  • fruiting heads are normally left on for Winter character, but may be pruned off for dried arrangements
  • basal suckers that occur with age can be removed annually, unless a slowly expanding colony of the shrub is desired

• Foliage
  • dark green, opposite, and overall very broadly ovate to elliptical
  • leaf margins are serrated, incised, and range from entire to seven-lobed, with deep sinuses and acuminate apices
  • leaves are up to 1' long, often resembling the foliage of Northern Red Oak (Quercus rubra), hence the common name
  • fall color in October and November is a mixture of green, wine, purple, maroon, red, and brown, with uniform fall color occuring in full sun (in shady areas, the fall color tends to be bronzy-green at abscission)

• Flowers
  • conical inflorescences terminate many stems and are up to 1' long each
  • showy white to cream sterile florets surround the greenish-yellow true flowers hidden underneath
  • the sterile florets gradually change to pink, lavender, bronze, and finally brown as the season progresses, flowering in June and persistent as a fruiting head into the next season
  • overall the many inflorescences create a showy, radiating effect of white flowers

• Fruits
  • true fruits are many small brown capsules and are ornamentally insignificant; however, the inflorescence with its persistent outer layer of sterile florets remains as a fruiting stalk, and is quite noticeable in Winter and into the following Summer if not removed

• Twigs
  • young twigs are very pubescent and orange-brown
  • bark is exfoliating in large flakes on older stems, revealing a cinnamon-orange smooth interior bark
  • large terminal floral buds are orange-brown and very pubescent; vegetative buds, whether terminal or lateral, are smaller versions
  • overall, the shrub is composed of several stout, crooked, and relatively few-branched stems (becoming more twiggy and suckering at maturity)

• Trunk
  • light orange-brown and exfoliating
  • several trunks and branches radiate from a common basal point at 45 degree angles, yielding an overall rounded shape to a vased branching pattern

• ID Summary
  • very large Northern Oak-like leaves are dark green above, with green-silver to green-brown pubescent undersides, having pubescent orange petioles and stems, exfoliating with age, forming a broad-rounded outline of bold character
  • huge inflorescences are conical, with an outer layer of white sterile flowers nearly covering the creamy miniature flowers underneath, in June and slowly transitioning to fruiting bodies during the Summer, with the sterile flowers changing to bronzy-pink then brown, and persisting into the following year as fruiting heads

• Function
  • specimen, focal point, flowering accent, foundation, entranceway, border, water's edge, mass planting, or naturalized area shrub

• Texture
  • bold texture when in foliage, flower, and when bare
  • open density in youth when in foliage, but thick density at maturity
  • always an open density when bare, irrespective of age

• Assets
  • large and showy white inflorescences in early Summer
  • bold year-round texture
  • exfoliating orange bark
  • wine-red Autumn coloration
  • wet site tolerant

• Liabilities
  • slow growth rate, especially in youth
  • dead fruiting stalks that persist into the following season
  • basal suckers with age
  • need to maintain a non-straggly growth habit through a small amount of judicious pruning if sited as a specimen plant
  • leaf chlorosis and reduced plant vigor will result if placed in very alkaline soils
  • inflorescences are so large that they will often droop

• Habitat
  • zones 5 to 9
  • native to the Deep South of the United States

• Alternates
  • shrubs with Summer flowering (Clethra alnifolia, Hibiscus syriacus, Hydrangea macrophylla, Itea virginica, etc.)
  • shrubs with ornamental stems or bark (Cornus alba, Cornus sericea, Corylus avellana 'Contorta', Euonymus alata [species form], Kerria japonica, etc.)
  • shrubs with bold texture (Aralia spinosa, Hydrangea species, Magnolia hybrids, Rhus typina, Syringa vulgaris, etc.)

• Variants
  • Hydrangea quercifolia 'Snow Queen' - bold inflorescences are held more vertically, with larger and more dense sterile florets that turn a consistent pink in Summer, while the dark green Summer foliage turns a consistent red-bronze in Autumn; this will be the cultivar of choice as soon as supply meets demand

• Translation
  • Hydrangea translates as "water vessel", referring to the miniature cup-shaped fruits.
  • quercifolia translates as "oak-like leaves", referring to their oak-foliage appearance.

• Purpose
  • Oakleaf Hydrangea is a bold-textured, four-season shrub, especially noted for its large white Summer inflorescences.

• Summary
  • Hydrangea quercifolia is a four-season shrub (large dark green Spring and Summer foliage, prominent white Summer inflorescences, good wine-red fall color, and fruiting stalks coupled with exfoliating orange bark during the Winter).