Hydrangeas

For a while hydrangeas went out of fashion. Perhaps it was their association with grandmas’ gardens that gave them a dated feel. You only have to visit the John Madejski Garden in the contemporary Italianate courtyard of the Victoria & Albert Museum to see how wrong this notion is.

Nearly all hydrangeas are shrubs and the most familiar is the mop-head, which will be covered in large pom-pom shaped flowers for the next month. If you prefer a more subtle look, lace-cap hydrangeas have clusters of tiny fertile flowers surrounded by larger sterile blooms.

Flower colour varies and is generally governed by pH and the amount of aluminium ions in your soil. Blue flowers suggest your soil is on the acidic side (opposite to litmus paper, confusingly) and pink hydrangea flowers in soils with a pH of 5.5 of more.

One of the challenges of using hydrangeas is their bold colour and form. It can be difficult to balance their presence in a garden to create a calm and unified space.

You can soften mop-heads’ flower colour by teaming them with plants that are flowering at the same time with similar shades, such as astilbes, geraniums, phloxes, liatris, penstemons and persicaria. Hydrangeas can be remarkably tolerant of a wide variety of growing conditions from woodland situations with dapple shade to full sun. They prefer their ‘feet’ to be moist but once established are tolerant to periods of dryness.

Some hydrangeas with a round, compact habit are a visual full stop even before the flowers appear and it is helpful to counterbalance their static appearance by placing them next door to a plant with flowing lines like weeping Cercidophyllum japonicum ‘Pendulum’. Bold, simple, elliptical hydrangea leaves look great when placed against detail, like the fine foliage of a fern, grass or the blades of a crocosmia or a day lily; preferably something that will hide or add to the bare, naked hydrangea stems in winter.

Flowers are the cherry on top of the cake when it comes planting designs. For a flamboyant colour scheme, orange crocosmia looks fabulous planted in front of blue hydrangea. The wow factor can be added to with the blues of a perovskia, the purples of Verbena bonariensis and Salvia nemorosa ‘Caradonna’

Pink flowering hydrangeas look particularly good planted in front of a purple foil like that of Cercis canadensis ‘Forest Pansy; Berberis thunbergii f. atropurpurea, Cotinus coggygria ‘Royal Purple’ and Acer palamatum ‘Bloodgood’. For a more subtle the soft-green palmate leaves of Acer palmatum look wonderful against hydrangeas with bold, broad and ovate leaves.

Published in ‘at Home’ a supplement of the Scotland on Sunday on 5 September August 2010