One of the most beloved flowers grows on a plain, ordinary shrub. But there’s really nothing plain or ordinary about the hydrangea. Granted, hydrangeas tend to blend in at first. Then they start blooming and all bets are off.
Although there are dozens of species, the four most popular shrub hydrangeas all have one thing in common: large flowers that captivate up close or from a distance. Some hydrangeas take more sun and heat than others, but all do best with ample moisture.
Here’s a closer look at some great hydrangeas for your yard.
Among hydrangeas, bigleaf hydrangeas (H. macrophylla) may have the showiest flowers of all — usually in bright hues of pink or blue. Mopheads have big dome-shape flower clusters, while lacecaps have lacy-looking flowerheads featuring a mix of large and small florets.
Bigleaf hydrangeas do best in partial shade in moist, well-drained soil. Afternoon shade is preferred, but all-day shade will result in green plants and no flowers. Some cultivars are available with variegated or lime-green foliage, giving them multiseason appeal.
Size: 3–5 feet tall, depending on cultivar.
Hardiness: While a few bigleaf hydrangea cultivars are hardy to Zone 4, most grow in Zones 5 or 6–9.
Good to Know: The color of bigleaf hydrangea blooms depends on soil pH. If the soil is acidic (5.5 pH or lower), flowers are blue; if the soil is alkaline (above 7.0 pH), flowers are pink. You can acidify the soil with sulfur or aluminum sulfate, or make it more alkaline by adding dolomitic lime. Use a pH meter, available at Lowe’s (#251966). Keep in mind that the plant grows best in soil below 7.5 pH.
Panicle hydrangea (H. paniculata) is more forgiving than other hydrangeas when it comes to sunlight and watering. In fact, it will take full sun in the North. A few hours of shade every day is helpful in the South. It’s comparatively easy to grow.
Panicle hydrangea blooms later in the season, from midsummer to fall, when few other shrubs are blooming. The large cones of white flower clusters fade to pink and tan as they age. Some have attractive golden-yellow fall foliage, too.
One popular cultivar is ‘Limelight’ (see photo at top of story), which has greenish-white flower clusters fading to pink and tan. Another is ‘Pee Gee’ (shown), which grows 20 feet tall and can be pruned into a tree shape.
Size: generally 5–10 feet tall, although there are smaller cultivars available.
Hardiness: Panicle hydrangea is the hardiest species, thriving in Zones 3–8.
Good to Know: Because panicle hydrangeas are larger and accept more sunlight than other hydrangeas, they work well in a shrub row or privacy screen. You can also use this larger species as a focal point, filling in a bare corner or as a sentinel near the doorway.
Smooth hydrangea (H. arborescens), is named for its large, smooth leaves. Sometimes called snowball hydrangea, smooth hydrangea can take full sun if the soil stays moist, but part shade is best in most other situations.
‘Annabelle’ is the best-known cultivar, with huge flowers in early summer. Flowers start out white, then fade to green and tan. Other cultivars have pink flowers.
Size: grows 3–5 feet tall; can be kept shorter with annual hard pruning.
Hardiness: Smooth hydrangea is hardy in Zones 4–9. Some winterkill may occur but it easily rebounds after shearing in late winter or early spring.
Good to Know: These hydrangeas tend to flop after rain, so support plants with a wire frame to keep them upright and looking their best.
Oakleaf hydrangea (H. quercifolia) gets its common name from the oaklike foliage. The big, coarse leaves add texture to the garden and are an even bigger hit in fall when they turn hues of crimson, burgundy, and purple. It also has peeling cinnamon-color bark for winter interest.
But it’s the large cone-shape clusters of white flowers that captivate most gardeners. They age to pink or tan as temperatures cool, and they hang on the plant into winter. Oakleaf hydrangea is more tolerant of dry soils than other hydrangeas.
Size: grows about 6 feet tall and up to 8 feet wide if not pruned.
Hardiness: Oakleaf hydrangea is hardy from Zones 5–9.
How and When to Prune Hydrangeas
Hydrangeas require little pruning, other than to decrease the size of the shrubs. But it’s good to remove broken or dead stems and thin out crowded growth. Here are pruning tips for the most popular species.
Bigleaf hydrangeas: bloom on old wood (last year’s growth), forming the next year’s flower buds after flowering, so prune immediately after flowers fade. Exception: Some new varieties, such as Endless Summer, bloom on both old and new wood, so prune later in the year.
Panicle hydrangeas: bloom on new wood (this year’s growth), so prune any time except early summer, when flowerheads are forming. For bigger flowers, thin to 5–10 main shoots.
Smooth hydrangeas: bloom on new wood (this year’s growth), so cut back hard in late winter or early spring to encourage bigger flowers and a neater habit.
Oakleaf hydrangeas: bloom on old wood (last season’s growth), so prune no later than midsummer. Old specimens may benefit from thinning. Remove one-third of the oldest, thickest stems for three years.