Revolutionary colour-changing plants
How do you grow hydrangeas? That’s the question many new gardeners are asking, as the shrubs have rocketed in popularity, thanks to a flood of new varieties.
The RHS Chelsea Plant of the Year Hydrangea Runaway Bride Snow White is one of the new breed. Far from the staid shrubs of the 1970s, the new hydrangeas are at home in pots or in a border.
I wasn’t a fan until I visited Madeira. Hydrangeas grew alongside agapanthus, palms, and bird of paradise flowers – combos that worked. There were roadsides up in the mountains, covered with wild garden escapees, looking utterly gorgeous. Back home, I hightailed it to a garden centre with my father-in-law. I bought the lacecap Zorro and he plumped for Deep Purple Dance.
How to grow hydrangeas – Colour-changing flowers
Mophead and lacecap cultivars of H. macrophylla, H. involucrata and H. serrata can change colour. This is due to the soil pH which affects the amount of trace element aluminium the plant can absorb.
Those with blue or pink flowers tend to be blue in acid soil (high aluminium), mauve in acid–neutral soil, and pink in alkaline conditions. To get the flower colour you want, choose cultivars that give the best colours for your soil. White and green-flowered cultivars don’t share this quirk.
Recommended varieties: Magical Hydrangeas
Capitalising on H. macrophylla’s tendency to colour change, the Magical Hydrangea Four Seasons series is a real head-turner. The heavy flower heads change colour at least three or four times a year. The display lasts for six months, from May to November, in a shady, moderately warm spot.
They’re easy to care for, ideal for beginners, are compact and look good in borders. Plants are available in 3.5, 5 and 10-litre pots. The Magical Hydrangea is grown exclusively in the UK by Wyevale Nurseries in Hereford.
There are eight varieties, including Magical Ruby Tuesday. It won the Plantarium 2015 Best in Show and silver at the HTA National Plant Show 2016. Magical Revolution Pink starts apple green, changing to pale pink, then dark pink and finishes green with dark red edges.
The other six are Magical Revolution Blue, Magical Amethyst Blue, Magical Amethyst Pink, Magical Coral Blue, Magical Coral Pink and Magical Noblesse. Plants are widely available, including at Homebase and Dobbies.
Potted guide: How to grow hydrangeas
- Shrubs thrive in moist, well-drained soil, in a cool, semi-shady spot. Avoid exposed east-facing sites, or dry, sunny areas.
- Work plenty of organic matter into the soil before planting. After planting, apply well-rotted manure, leafmould, bark or compost each spring as a mulch.
- Feed annually in late winter or spring. Too much feeding can encourage soft, leafy growth, with plants less likely to develop flower buds.
- Prune climbing hydrangeas (H. anomala subsp. petiolaris, H. seemanii) after flowering. Cut off spent flower heads and trim unwanted shoots back to healthy buds.
- Prune shrubby hydrangeas (H. macrophylla, H. paniculata and H. quercifolia) in early spring if necessary.
- Use rainwater to water hydrangeas, since tap water can affect the flower colour.
- Keep blue flowers the right shade by growing in acidic soil (pH 4.5-5). You can add a ‘blueing compound’, which contains aluminium sulphate. If the soil is very alkaline, it will not work.
- To enhance red or pink flowers, apply a dressing of ground limestone or chalk in winter.
