Native to Japan, Hydrangea macrophylla (Big Leaf Hydrangea) is one of the most popular hydrangeas in our gardens. This deciduous shrub enjoys a rounded habit, large bold leaves and attractive clusters of long-blooming summer flowers. The species is divided into two groups: the Mophead Hydrangeas and the Lacecap Hydrangeas.
- The Mophead Hydrangeas or Hortensias produce large rounded flower heads, mostly packed with showy sterile florets. Since the flowers cannot be pollinated, they will bloom on and on through summer, between 3-6 months, until fall approaches and they change color. The color changes can be quite spectacular with rich blues turning wine-red or whites changing to pale green and even blood-red.
- The Lacecap Hydrangeas produce flattened flower clusters composed of showy sterile florets radiating around a central cluster of tiny fertile florets. Since the fertile florets will be pollinated, the lacecap flowers will fade much faster than the mopheads, remaining superb about one month.
- There is a great range of color to choose from: deep blues, vibrant pinks, pristine whites, lavender, and vivid shades of red and purple. Most of the Hydrangea macrophylla cultivars have the added attraction of changing color, depending on the soil pH. Strongly acidic soils allow these species to produce blue flowers; slightly acidic soils will produce pink flowers. To change the color of your Hydrangea, add aluminum sulfate to the soil to make the flowers bluer or add lime to the soil to make them pinker.
- Hardy to zones 6-9, Bigleaf Hydrangeas are more vulnerable to cold than their cousins and welcome a good layer of mulch year-round (shredded bark, peat or compost ). This will suppress weeds, retain moisture, reduce temperature fluctuations in the soil.
- Sun to part shade lovers, Bigleaf Hydrangeas are best grown in rich, medium moisture, well-drained soils. They tolerate full sun only if they are grown in consistently moist soils.
- No serious pest or disease issues. Watch for bud blight, bacterial wilt, leaf spot and mildew.
- Perfect from foundation plantings to container plantings. Massed in a sheltered location or as an accent plant. Effective as a hedge, they make excellent cut flowers too! Perfect for seaside gardens as their tough, glossy leaves allow them to withstand wind or salt.
- Bigleaf Hydrangeas should be pruned after flowering by cutting back the stems to a pair of healthy buds. Prune out weak or winter-damaged stems in early spring.