Bigleaf Hydrangea
Hydrangea macrophylla
Other names: Mophead hydrangea, French hydrangea, lacecap hydrangea
Bigleaf hydrangea is the classic hydrangea with rounded mophead or flat lacecap flowers in blue, pink or purple. It grows best with morning sun, afternoon shade and steady moisture. On most varieties, the flower color changes with the acidity of the soil.
How to grow bigleaf hydrangea
Light
Morning sun with afternoon shade is ideal. In cool, northern climates it tolerates more sun. In hot regions it needs shade from midday onward.
Watering
Keep the soil consistently moist. Water deeply two or three times a week in hot weather. The leaves wilt quickly when dry. A 3 in (8 cm) mulch helps a great deal.
Soil and feeding
Plant in soil enriched with compost. In acidic soil, below about pH 5.5, the flowers turn blue because aluminum is available to the plant. Above about pH 6.5 they turn pink. White varieties stay white.
Planting and pruning
Most varieties flower on old wood, the stems grown the previous year. Prune only right after flowering, removing spent blooms and a few of the oldest stems. Pruning in fall, winter or spring removes that year's flower buds. Reblooming varieties flower on both old and new wood.
Propagation
Take softwood cuttings in early summer, or pin a low branch to the ground and separate it once it has rooted.
Common problems
- No flowers
- Pruning at the wrong time, or flower buds killed by winter cold or a late frost. Protect plants in cold winters and prune only after blooming.
- Leaves wilt every afternoon
- Heat and thirst. Water deeply, mulch, and give more afternoon shade.
- Purple-brown leaf spots
- Cercospora leaf spot in humid weather. Clear fallen leaves and water at soil level.
Questions about bigleaf hydrangea
How do I turn my hydrangea blue?
Lower the soil pH to between 5.0 and 5.5 by applying aluminum sulfate or garden sulfur according to the label. The change takes several months and works on pink and blue varieties, not white ones.
When should I prune a bigleaf hydrangea?
Immediately after it finishes flowering in summer, and no later than early August in most climates.
Plant details
| Botanical name | Hydrangea macrophylla |
|---|---|
| Family | Hydrangeaceae |
| Native range | Japan |
| Plant type | Trees and Shrubs. Deciduous shrub |
| Soil | Rich, moist, well-drained soil |
| Flower color | Blue, pink, purple, white |
- Good cut flower
- Grows in containers
- Tolerates shade
