There has never been a better time to fall in love with mop head hydrangea, H. macrophylla. Not only they are among the most valuable shrubs you can grow in a garden, recent years has seen an astonishing range of new varieties introduced, particularly from France and the Netherlands.
Mop heads are reliable, long-flowered and adaptable in a wide range of soils, even thriving in heavy clay or unimproved soil as long as they remain moist.
Recent years has seen an astonishing range of new varieties introduced, with different arrangements of the colourful petal-like bracts, some of them shifting colour over the season.
The most significant development has been those which types such as the Forever And Ever series, which bloom on old as well as new growth, expanding the length of display of bloom. This phenomenon also helps keep these varieties more compact, ideal for smaller gardens or pots, reducing the need to prune except to thin out congested shoots every so often.
Mop head hydrangeasare sensitive to the pH of soil, with alkaline soils encouraging them to bloom with pink tones and acidkeeping them blue, while those in the middle generate purple tones - the usual case in most soils and potting composts.
The element that causes the blue colour is aluminium and the aluminium sulphate contained in hydrangea colouring compounds when applied to soil or potting compost either as granules or liquid will help boost this colour, but it’s not instantaneous, taking time to come into effect.
There’s also no need to remove spend flower heads unless you want to, as old bronze-toned heads make attractive features in autumn and winter, especially when frosted and also act as hiding places for many beneficial insects, such as ladybirds and lacewings. They also look attractive on those varieties with black stems, which are visually more apparent once the deciduous foliage has fallen.
They do best in light or semi-shade in a damp, but well-drained soil, but are adaptable as long as the soil is not subject to prolonged drought, luxuriating in cool, humus-rich soils when they will perform to their best.
GN Recommends
Forever and Ever - Breakthrough variety blooming on young and older growth. Four colour forms. Height: 0.9m (3ft) Stem: 1.5m (5ft). Available from Signature Hydrangeas Tel: 01622 833218
Magical Four Seasons Noblesse - Distinctive variety, opening light green, becoming white with green tips, turning dark green in autumn. Height and Stem: 80cm (32in). Available from Jersey Plants Direct Tel: 01534 871113
You and Me Together - Remarkable double flowers change colour, opening green to soft pink, then darkening to rose red in autumn. Height and Stem: 0.9m (3ft). Available from CrocusTel: 01344 578111
Zebra - Aptly-named long-flowered variety with clean white flower heads perched on near jet-black stems. Height and Stem: 0.9m (3ft). Available from Crocus Tel: 01344 578111