Hydrangea heteromalla

The Hydrangea heteromalla is a beautiful botanical hydrangea that originates from the Himalayas. Despite its striking appearance and ease of care, it is not commonly found in gardens. This large bush has dark green foliage that turns autumnal hues and produces frothy, flattened flower heads that range from white to pink. These flowers remain decorative for a long time, making this species an excellent choice for large spaces as a backdrop. It is easy to grow in ordinary soil but prefers moist conditions.

Originating from the Himalayas, distributed in an area ranging from Nepal to the north of India, the Hydrangea heteromalla is a wild species of open forest habitat that also appreciates mountain slopes and can climb up to 2000m (6561 ft 8 in) in altitude. It is a large bush that needs light and minimal sun to flower well. It tolerates both cold (-20°C (-4 °F)) and heat (in a more shaded situation). It belongs to the hydrangea family and is a close relative of the large-leaved hydrangeas with ball-shaped inflorescences that need no introduction.

The heteromalla hydrangea grows slowly but forms a beautiful bush with a sprawling, rounded silhouette. It has upright main branches bearing flexible secondary branches, giving it a bushy habit. At maturity, it reaches a height of about 3.50m (11 ft 6 in) and a width of 3m (9 ft 10 in). This hydrangea has many-branched stems. The bark, initially hairy, flakes off over time and becomes almost corky and grey-brown. 

The abundant and long-lasting flowering usually occurs on the previous year's branches at the end of June or the beginning of July. The flower head is flat, wide, and 15 to 25cm (5.9 to 9.8 in). It comprises a few sterile flowers with 4 white petals, forming an irregular and sparse crown around the smaller fertile flowers. The latter, much more numerous, open into tiny white flowers with prominent stamens that often turn pink after pollination by insects. 

This hydrangea has deciduous foliage that disappears in winter. The foliage consists of long oval leaves, which are 10 to 15cm (3.9 to 5.9 in), carried by a red petiole. The leaves are slightly hairy, dark green on the upper side, almost white on the underside, and marked with fairly deep veins. The foliage takes on red colours during the summer (depending on exposure) before turning orange and purple in autumn.

Once well established, this magnificent bush requires very little care other than regular watering in dry summers. It likes lightly shaded or partially shaded areas, but it is one of the few, along with the Hydrangea quercifolia and H. aspera sargentiana, to be more tolerant of the presence of limestone (without excess) in the soil. Naturally, it will also thrive in an ericaceous bed alongside other hydrangeas, Pieris, or Chinese Azaleas. The Hydrangea heteromalla allows you to create a superb backdrop, to flower a free hedge with fragrant viburnums, or large deciduous euonymus. Also, place it at the edge of a grove or woodland. But preferably plant it near a pathway, as it would be a shame not to enjoy its presence and unique personality.