Hydrangea macrophylla is a species native to Japan and Korea. However, it is widely cultivated in many parts of the world in many climates, and a must have shrub for shade and partial shade being that is so showy. In this country we refer to it as a "French Hydrangea". In landscaping design, Hydrangea macrophylla add a splash of springtime color to shady areas and woodland gardens. Once hydrangeas become established, they can grow quite vigorously. If they do become prolific, occasional summer pruning is recommended to keep them in bounds. The flowers are easily air-dried and are long lasting making terrific indoor dcor displays.
Hydrangea macrophylla tends to grow ball shaped flowers. The blossoms are either pink or blue depending on the soil pH. If the pH of the soil is below 5.5, the flower tends to be blue. If soil pH is higher, they will be pink although some cultivars will retain their original color irrespective of soil pH. Soil pH can be changed (lowered) using aluminum sulfate available in garden centers. If you definitely want pink flowers, add lime instead.
Hydrangeas also come in a climbing variety, a flowering deciduous vine. Plant taxonomy classifies climbing hydrangeas as Hydrangea anomala ssp. petiolaris. Newly planted climbing hydrangea vines are slow to grow and slow to bloom. Once established, these plants are true climbers, using "holdfasts" to scale walls or trellises, good for shady areas. Grow climbing hydrangea vines up trees, garden arbors, pergolas and fences. Even though they won't flower as profusely if planted in full shade, these shade-tolerant vines provide attractive foliage that can cover quite an area once the plants mature.
In early summer, climbing hydrangeas produce fragrant, lacy, flat-topped, white flower heads. These "lace caps" can be five inches or more in width and are composed of showy flowers on the outside accompanied by less-than-showy flowers on the inside. The leaves of climbing hydrangea vines turn yellowish in autumn. The plants' exfoliating bark affords winter interest. Climbing hydrangeas that do get more sun tend to bloom more profusely. The soil should be moist, well-drained, and contain plenty of humus.