Great balls of f lower
Want a blast of colour this autumn? Look no further than hydrangeas and their...
THE other day, a neighbour asked me why the blue flowers on her mophead hydrangea had turned a murky pink. I’d normally want to see a plant before giving an accurate diagnosis of a problem, but there was no need for me to leave my front garden on this occasion.
I gave my neighbour an instant answer – there was nothing wrong. One of the peculiarities of some hydrangeas is that the flowers change colour depending on the pH of the soil. Blue varieties will go pink if planted in alkaline soils and mauve in more neutral conditions. Those with pink flowers will gradually turn blue in acidic soil.
This phenomenon largely occurs among popular mophead and lacecap varieties, along with some less common types. Those with white, cream or greenish flowers remain the same colour, regardless of conditions.
A soil additive, known as hydrangea colourant, is available to help pink hydrangeas turn blue, but the only certain way to ensure they remain the same colour is to buy a variety that’s suited to your soil.
There are close to 500 different types available in Britain, ranging in height from 3ft to more than 20ft. These shrubs generally start to bloom in late July, providing an exuberant display until October – some even have foliage that turns attractive shades of red, bronze and purple in autumn. All are ideal for planting now in a sunny or partially shaded spot.
There isn’t a large range of flower colours – largely shades of white, pink, blue and purple – yet this hardly matters when they are produced so prolifically for months on end. And blooms generally appear at a time when few other shrubs are strutting their stuff.
Hydrangeas are found in their biggest concentrations in Japan, China and South Korea. We’ve been growing them since the early 18th Century. The first to arrive here was Hydrangea arborescens, a large shrub with rounded white flowers from the United States. It was followed in 1788 by Hydrangea macrophylla, a species from Japan that is the parent of all mophead varieties.
The mopheads boast large, ball-like flowerheads made up of hundreds of small flowers, while lacecaps have a flattened flowerhead with a central cluster of tiny flowers surrounded by a ring of larger ones. Others have flowers arranged in large, conical plumes.
There are some cracking mophead varieties. Hydrangea macrophylla ‘Madame Emile Mouillere’ carries snowy white blooms on its 6ft branches, while H. macrophylla ‘Altona’ is a compact beauty with large heads of rich pink flowers. Crowned Chelsea Flower Show plant of the year in 2014, H. macrophylla ‘Miss Saori’ boasts large heads made up of double white flowers with cerise edges.
Many lacecap varieties are just as showy. H. macrophylla ‘Veitchii’ has graceful heads of small, lilac flowers surrounded by rings of snowy white flowers that turn red as they age, and H. macrophylla ‘Rotschwanz’ features deep crimson flowers.
FOR my money, the most desirable is Hydrangea arborescens ‘Annabelle’, with its 8in-wide spherical white flowers – it was originally discovered growing in Illinois back in 1910. Hydrangeas prefer well-drained soil and need a sheltered spot. Plant them in beds, borders or within a woodland-style garden. Alternatively, raise compact forms in large pots filled with good quality compost. Tap water is fine for most, but those in acidic compost need rainwater.
Keep lacecap varieties in shape by deadheading, cutting to the second pair of leaves beneath the fading flowerhead. Allow dead flowers to remain on mophead types over winter, then cut back to a healthy pair of buds. Most flower on the previous year’s wood, so avoid pruning hard in spring.