The secret hydrangea
They’re hugely popular shrubs – yet there’s one striking variety no one seems to know about
MENTION hydrangeas and most gardeners think of large shrubs with pink or blue flowerheads that brighten up gardens from late summer into autumn. But these popular mophead and lacecap types are not alone. There’s a less celebrated group that have even more spectacular flowers.
Panicled hydrangeas are the unsung heroes that deserve to be better known. They are hardier, more drought-tolerant and less picky about soil conditions than their close relatives, and some produce outrageously large flowerheads, often from late July until November.
Despite their many attributes, panicled hydrangeas have never come close to rivalling other species in terms of popularity. Perhaps this is due to their fairly awful name – in botany, a panicle is a cluster of flowers held together to form a broad conical shape.
Unfortunately, this lack of attention has meant that many gardeners miss out on enjoying their creamy white, green, pink and near-red heads that measure from 4in to 18in in length.
Hydrangea paniculata is native to China, Japan and Sakhalin, a large Russian island in the Pacific Ocean. This deciduous shrub can reach 26ft in the wild.
German botanist Philipp Franz von Siebold was the first Westerner to clap eyes on this magnificent plant in 1829, while working for the Dutch East India Company in Japan. Unfortunately, he was accused of being a Russian spy and expelled from the country. Thirty years later he was allowed to return and eventually sent home specimens of Hydrangea paniculata ‘Grandiflora’, a cultivated form with 12in white flowerheads.
Despite being available since the mid-19th Century, plant breeding was slow to take off. Very few Hydrangea paniculata varieties made their debut during the 20th Century and the first edition of the RHS Plant Finder guide, from 1987, named just eight. The current version lists almost 80 different ones.
Hydrangea paniculata ‘Tardiva’ has been around for ages but is still among the best varieties thanks to its 11in-long flowerheads that appear from early to late autumn. ‘Phantom’ was introduced in the 1990s and boasts dense, tapering white flowerheads. Dating back to 1926, H. paniculata ‘Kyushu’ was discovered on the Japanese island of the same name by British plant-hunter Collingwood Ingram. The loose, white flowerheads appear from late summer to mid-autumn, attracting bees and other pollinating insects. For my money, the best of all is H. paniculata ‘Limelight’. It forms an 8ft-wide by 8ft-tall shrub, clothed with flowerheads from midsummer into November. Blooms start off a lime-green colour, turn to white and ripen to pink with the arrival of frosts. Many other varieties have flowers that age to pink, including ‘Burgundy Lace’, ‘Vanilla Fraise’ and ‘Pink Diamond’. The tiny flowers of ‘Pinky Winky’ gradually turn from white to pink on flowerheads, giving them a distinctive two-tone effect. Bred in the US, it reaches just 6ft. The panicled hydrangea with flowers that turn darkest of all is ‘Wim’s Red’, a gorgeous variety with striking magenta branches of up to 6ft 6in. The flowers start off white in midsummer, turn pink, and end up a rich burgundy red in autumn. Even after this, the fading flowerheads continue to provide interest. Panicled hydrangeas aren’t as fussy about the pH of soil as other types, but do require moist, fertile ground with plenty of organic matter. They’re happy in sun or partial shade, and are best given a sheltered spot. They are great in woodland gardens, mixed borders or even in a shady corner, where their cool white flowers will illuminate the gloom. Panicled hydrangeas can also make an attractive flowering hedge – plant individual shrubs 3ft apart in a row. As they lose all their leaves in winter, they are best used for internal barriers, rather than around perimeters, where privacy might be required.
If left to their own devices, panicled hydrangeas will become an overgrown eyesore. Keep plants compact by pruning annually. Establish a permanent, 2ft-high woody framework of branches, and then cut all of last year’s shoots back to within 2in of this older wood in early spring.
Plants will respond with a flush of 6ft stems and fewer but larger flowerheads.