New-look hydrangeas
Hydrangeas are enjoying a renaissance, and there’s lots to love, says JENNIFER STACKHOUSE
Yes, these are hydrangeas and they’ve had something of a makeover! Those cute double flowers, repeat bloomers and plants that are compact enough to grow in containers are the face of a new generation of an old favourite.
Hydrangea (Hydrangea macrophylla) is native to Japan, and that’s where some exciting new breeding work has been taking place. Breeding has also been underway in the US for several decades, and it was there that the modern hydrangea revolution really kicked off.
Back in 2004, Michael Dirr of Michael Dirr’s Plants introduced the first of the Endless Summer collection of hydrangeas, which flower on new growth, meaning they keep flowering through summer and into autumn. Gardeners in the US welcomed these repeat-flowering plants with open arms, and they were soon available in Australia. By 2011, some 18 million plants had been sold across the world. The success of Endless
Summer has led to the release of many other long-flowering varieties.
Not only does its long flowering make this a better performer than older varieties, it also overcomes problems that cause non-flowering. As traditional hydrangeas flower on last season’s growth, late or over-zealous pruning can cause old-style hydrangeas to fail to flower. Hard pruning in winter or late frost in spring can remove the next summer’s flowers. With Endless Summer, the flowers form on new and old wood, so hard pruning or frost doesn’t stop flowering as new flowering wood is formed right through summer.
COLOUR & FORM
H. macrophylla is known for its variable flower colour – blue in acid soils and pink in alkaline conditions. This variation is due to the availability of aluminium ions in the soil. The greater availability of aluminium in acid soils leads to increased blue colouration in the flowers. Endless Summer and other modern hydrangea varieties continue to exhibit blue tones in acid soils and pink in alkaline.
As well as having a range of colour forms, H. macrophylla has two types of flower heads. Commonly grown and seen in gardens are mophead varieties that produce flower heads made up of a mass of small, infertile flowers. Daintier and less familiar are lacecap hydrangeas, which have a central cluster of fertile flowers surrounded by a fringe of infertile flowers.
Lacecaps are part of modern hydrangea breeding, and it was in lacecaps that the next big thing in hydrangea development occurred, with the appearance of plants with bicolour flowers.
Anthony Tesselaar International unveiled the pretty lacecap hydrangeas ‘Strawberries & Cream’ (head of pink sterile flowers surrounding a centre of white fertile flowers) and ‘Blueberries & Cream’ (blue sterile flowers surrounding a centre of pale blue fertile flowers), which grow to about 1m high and wide.
These compact varieties are now marketed around the world for gardens and containers, and for use indoors as flowering pot plants. It is recommended to return the plants to a sheltered spot outdoors after they have been inside in a brightly lit spot for four to six weeks.
DOUBLE FLOWERS
In 2016, double hydrangeas arrived in Australia. They are very pretty with high visual appeal and it’s no wonder they sold out quickly in their first year of release.
‘Love’ has heads of small, round, double pale pink (or pale blue) flowers, ‘Perfection’ has bright pink (or blue) double flowers and ‘Miss Saori’ has white or green-tinged double flowers edged in deep rose pink, with foliage that develops deep crimson autumn tones. They are ideal for pots as they grow about 1m high and wide.
These hydrangeas were bred in Japan and have won awards around the world. Breeder Ryoji Irie named ‘Miss Saori’ for his wife, and this beautiful new variety was awarded Plant of the Year at the RHS Chelsea Flower Show in 2014. They are grown in Australia by Sprint Horticulture and sold under the Tea Time label.
LONG FLOWERING
And new hydrangeas keep on coming.
New this year for Australia is ‘Magical Revolution’, a hydrangea that promises blooms for 150 days. That’s almost six months of flowering, from late spring to autumn. Flowers are pink or blue (depending on soil pH) but age to pink then burgundy. Long-lived flower heads form on compact plants 60–70cm high and wide.
‘Magical Revolution’ is an ideal gift and grows well in containers. It can be kept indoors in a brightly lit spot and is useful for narrow, shaded spots outside, such as between the driveway and fence. Expect to see them in nurseries at Christmas.