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Features
This is a relatively small shrub which has broad, dark green, deeply toothed leaves from spring to autumn. Large flowerheads appear in early summer, starting off yellow/green, turning pink in summer (or purple-blue if you’re on acid soil) before fading to red into autumn. The flowers remain on the shrub and can provide winter interest.
What to use it for
A ubiquitous plant for cottage garden beds and borders. Great for low maintenance schemes and can also be grown in large containers. The flowers are useful for arrangements, both fresh and dried.
How to look after it
If you have neutral or slightly alkaline soil but would like bluer flowers, then add a ‘blueing compound’ (which contains aluminium sulphate) every week to fortnight. If your soil is very alkaline then this is unlikely to work.
How to prune it
In warm climates you can prune in summer after flowering. If you live in a cold climate (or if you want to retain the dried flowerheads for winter interest) don’t prune until mid spring as the flowerheads will help to protect the stems from the winter cold.
Pruning should be kept to a minimum at first, only cutting off the dead flowerheads to a pair of healthy buds. Once the plant is established you should remove any dead, diseased, damaged or weak growth, then cut back one or two old stems to the base to encourage new growth and a compact shape. When removing the dead flowerheads take the stem back by up to 30cm to a pair of healthy buds.
Straggly plants or specimens which have been badly damaged by cold winter temperatures can be cut down to their base in spring, but you will not get any flowers that year because the plant flowers on old (last season’s) growth.
How to propagate it
Take softwood cuttings, using shoots without flower buds, from late spring to midsummer. Each cutting should have 2 to 3 pairs of leaves. Remove the lower leaves and the soft tip of the cutting, it should end up about 4 to 5cm long. If the remaining leaves are large then cut them in half to reduce moisture loss. Put the cuttings in a shady place, ideally in a propagator, and they should root within 4 weeks (applying bottom heat of 15°C will speed it up). The new growth should be pinched out to maintain a compact habit.
The flowers are sterile so it can’t be propagated by seed.
Common problems
Can have problems with aphids, capsid bugs, two spotted spider mites, stem eelworms and hydrangea scale. Diseases affecting hydrangeas include grey mould, hydrangea ringspot virus, powdery mildew, leaf spots, stem and leaf rot, and root and foot rot. Iron deficiencies can also be an issue.
Other useful information
This hydrangea has been given the Award of Garden Merit by the RHS.
‘Altona’ is a German cultivar first introduced in 1931.
The genus name Hydrangea derives from the Greek words ‘hydro’ and ‘aggos’ meaning ‘water jar’; referring to the cup-shaped form of the fruit capsules. The species name macrophylla means large-leaved.
Extracts from the leaves of Hydrangea macrophylla are being investigated as possible sources of antimalarial and anti-diabetic drugs.
Plant parts can cause a stomach upset if eaten and the leaves can aggravate skin allergies.
