Their colouring will undergo remarkable transformations from vulgar pink to rich ruddy purples before turning a bleached shade of brown. The blues will turn to dusky silvery greys, hanging on to their flowerheads right into winter, and they make excellent dried flowers.
However, the rounded and crisp artificiality of mopheads tends to make them look out of place in naturalistic settings and woodland gardens. Their counterparts are the more poetically named lacecaps, whose papery bracts (flower-like modified leaves) circle a mauve to pink head of minuscule flowers. Sophisticates with wild gardens tend to prefer this type.
The lacey finery is at its best in Hydrangea villosa. It grows to two metres high and wide, with elegant long, hairy, pointed leaves. The flowers, in the best forms, are rosy-lilac to violet-blue, often with a hint of pink. The bracts are paler but float beautifully in a ring around the flower.
The best of the closest forms to H villosa are H aspera ‘Mauvette’ and ‘Sam Macdonald’, but it is worth hunting around for a good form of H villosa, from a specialist nursery. H aspera and the even larger H sargentiana are much coarser but are prized for their foliage, which can be up to 30cm long by 15cm wide. These need a lot of space and must not be placed in a windy position.
Rich, cool soils suit these varieties best, but they are also happy in acid or limy soils, thriving even in chalk. Limy soil does not affect the colour of their flowers as it does mopheads (blue mopheads tend to turn pink in limy soils). They prefer a bit of shade, but not too much, so if you are planting in a woodland, make sure they get some dappled sunlight; this will show them off better too. They can be planted against the north, east or west side of a house, but with protection against shredding and scorching winds. Although they like it rich and cool, make sure they do not get too wet, especially in winter.
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They are a bit frost-prone in the spring, but extraordinarily resilient. In a Shropshire garden by a river where late frosts are frequent, I have watched H villosa get severe frostbite over two or three successive weeks. The unsightly frazzled foliage soon falls away and new shoots eventually appear, as ready to flower as the early shoots. This is another advantage they have over mopheads whose flower buds, if frosted, do not bounce back anew.
Young plants will need some protection in their first year. Mature plants, which often grow wider than they grow tall, develop a good framework of stems with flaky fawn bark. Old stems can be cut right back in late winter to encourage larger, bolder shoots. The plants flower from late July until well into September, depending on where you live.
The other hydrangea species that flowers in high summer is the white cone-flowered H paniculata. This tough plant can be treated with the same brutality as buddleias, so cut it back hard in spring. The result is often long stems with huge white panicles, quite unlike any other hydrangea.
The best forms are ‘Grandiflora’, ‘Tardiva’ and ‘Kyushu’, but any of them are worth trying and, like mopheads, they make excellent dried flowers.
H paniculata can be planted in a bit of shade or right out in the open, where it looks tremendous in borders along with perovskias, Japanese anemones and echinacea.
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So, if you disdain hydrangeas for their unexpressive blobbiness, have another look. You should be impressed.