Plant type: Deciduous shrub
Hardiness: USDA Zones 6 to 9
Bigleaf hydrangeas, a common shrub in the Southeast, are divided into two classes--the mopheads and the lacecaps. There are hundreds of cultivars in each group. Both shrubs flower in the summer, timing dependent on the type and cultivar, and there's considerable variation in flowers. As its name suggests, these hydrangeas have large leaves, giving it a coarse texture in summer. In the winter, the unbranched, vertical stems give the shrub a hopelessly coarse look.
The flower color of some of these hydrangeas depend on the pH of the soil (and, more directly, on how much aluminum is available in the soil). Although there are many exceptions, a pH of 5.0 to 5.5 will result in blue flowers and a pH of above 6 may mean pink flowers.
Bigleaf hydrangeas need moist, well-drained organic soil. Give it full sun to part shade; in the South, shade is essential. Mulch is helpful to help retain soil moisture. Do any pruning immediately after flowering; this shrub flowers on the previous season's growth (there are some exceptions among the cultivars).
How to Use
Place hydrangeas in the shrub border where its summer flower show can be appreciated and its less-than-great winter form recedes into the background.
Selected Mophead Cultivars
- 'Penny Mac'. A rebloomer, this cultivar keeps producing its medium-blue balls until frost.
- Pink Elf(tm) (formerly, 'Pia'). Pink, three- to four-inch flowers on a compact (two- to three-foot) shrub.
- 'Forever Pink'. Flowers earlier than most other mopheads, with three- to four-inch pink clusters that turn rosy-red in cool weather. Compact shrub to three feet. Flowers on current season's growth.
Selected Lacecap Cultivars
- 'Lilacina'. The outer, sterile flowers are mauve, the inner fertile flowers are dark blue.
- 'Blue Wave'. Sepals have wavy edges. Blue in acid soils, pink or lilac in more neutral soils.
- 'Variegata'. Foliage is variegated, with creamy-white leaf margins. The inner flowers are blue in acid soils, pink in neutral; the outer flowers are usually white, tinged with the color of the inner flowers. Three-foot-tall shrub.