Hydrangeas are one of my favourite summer blooms, both outside in the garden or as cut flowers inside, and their bold heads of white, pink, red and blue are a familiar sight in our summer gardens.
These chameleon-like shrubs, give them a change of condition and they’ll change colour, will often grow without any existing attention, although they respond well to a bit of feeding and pruning.
If you have acidic soil, you’ll produce blue flowers, an alkaline soil induces a pink tone. It’s the aluminium content in your soil that influences the colour — to maintain a blue colour, aluminium must be present, to maintain that pink or red colour, you need to take aluminium away. Add lime to your soil for that pink look, or for blue blooms treat your plants with Hydrangea Blueing Tonic from Yates. White hydrangeas, such as the exquisite ‘Trophy’, aren’t affected either way.
The most commonly grown hydrangeas are mopheads (Hydrangea macrophylla), and lacecaps (Hydrangea macrophylla var. normalis), but there are two other species well worth growing.
Paniculata hydrangea (Hydrangea paniculata), sometimes called PeeGee hydrangea, is a beautiful Chinese and Japanese native species, and one of the showiest of flowering shrubs. Distinctive pyramid-shaped clusters of creamy-white blooms mature to pink and each panicle can reach 45cm long — the plant can be pruned to a single leader to form a small weeping tree.
The oak-leaf hydrangea (Hydrangea quercifolia) is a native of south-eastern United States, and also has pyramid-shaped creamy-white flowers, but its deeply lobed, oak-like leaves develop spectacular red, orange and burgundy tones in autumn, staying on the bush until well into winter. This broad, rounded bush is worth growing for its foliage alone, and like the paniculata hydrangeas, it will thrive in drier locations — it also makes an interesting container plant.
Hydrangeas are almost the perfect cut flower — you only need three or four heads to fill a vase, and drying the blooms is easy, although the secret is choosing the right time to pick. I’ve found harvesting flower heads at the height of the summer season rarely works — the fresh blooms wilt and don’t dry well. Pick them when they’ve already dried a little on the plant — that means late summer or early autumn, when the petals begin to age and take on their rustic look — my blue hydrangeas age to a pink- green colour with hints of burgundy. After picking, remove the leaves and place in a vase, either with or without water, and leave to dry.