Hydrangeas are grown for their long-lasting flowers, but these northern hemisphere plants vary in their needs, so careful choices need to be made.
The most common, Hydrangea macrophylla, is a Japanese native used to a summer soaking in their rainy season, so it's not for dry gardens.
If you have a dry garden, opt for a North American species instead such as the summer-flowering, green-budded white Hydrangea arborescens ‘Annabelle’.
If you want a hydrangea for a shady position opt for the autumn-flowering Hydrangea paniculata instead.
Find out how to grow Hydrangea paniculata 'Limelight'
Where to plant hydrangeas
The one common thing about all hydrangeas is a need for a sheltered position out of the wind. Leaves scorch horribly in windy gardens and plants fail to do well. They also prefer some shade - even the drought-tolerant American species. The climbers are very good in shade. Hydrangeas do well under trees - particularly H. paniculata.
Position your hydrangea so that it avoids the midday sun on its roots. Some gardeners place hydrangeas on the sunless side of a low garden wall to keep the roots cool. Generally light shade is best for most, or afternoon and evening sun.
Hydrangea arborescens will take whatever the weather throws at it. However on damp soils, or in wet summers, it can become invasive and land grab from other plants.
Always avoid frost pockets, because early and late frosts are resented by hydrangeas and this is why they do so well in a maritime climate that avoids extremes.
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When to plant hydrangeas
Plant hydrangeas in the spring.
How to plant
Dig a large hole and add plenty of organic material such as garden compost, or add John Innes no 3 because this compost contains loam. Both will help to retain moisture in the ground.
Mulch with bark to keep the soil moister. Water well in the first growing season and be prepared to water in every dry summer. The best technique is to gently tip a bucket of water over the roots about once a week.
When hydrangeas blooms
Hydrangea blooms at different times depending on variety, but it is usually in summer.
Don't prune hydrangea macrophylla or Hydrangea serrata unless you need to, and never prune hard as you will cut away all the flowers. If there is die back after a hard winter then prune to the lowest emerging buds. If you do need to prune a mature specimen of Hydrangea macrophylla remove one or two stems at the base during spring, but leave several intact. Cutting back entirely will mean you do not get flowers until the following year.
Other types of hydrangeas are more forgiving, although most (including H. aspera, H. quercifolia and H. sargentiana) need only minimal pruning to remove dead stems in spring.
Hydrangea arborescens can tolerate drought, heat and extreme cold. In very cold winters it will die down completely and reshoot in spring, to flower in July. In milder winters it will grow away and flower four weeks earlier.
When to take hydrangea cuttings
Start new cuttings early in the summer to give them the best chance for surviving the winter.
Hydrangea flowers dry well if picked at their peak, or they can be picked as they fade as well.
Cut back to shooting buds in spring and then use a slow-release fertiliser (like 6 x) or sprinkle blood, fish and bone.
Changing hydrangea colour
Hydrangea colour varies depending on the soil. Add sequestered iron if you want blue flowers.
Find out about how to test your soil's pH level
Hydrangeas produce showy heads in a variety of forms from lacecap, to rounded mophead, to showy lilac-like panicle. They owe their diversity to the fact that the twenty-three species are now divided between America and Asia following the Continental Drift which split up the single land mass.
The difference between Asian and American varieties
To generalise, the Asian species tend to thrive on moisture and they prefer rainy summers and an ambient climate for nine months of the year, although they are hardy enough to survive cold winters. This weather pattern mimics the rainy season found all across Asia. The main Asian species is Hydrangea macrophylla, but others include Hydrangea serrata and Hydrangea paniculata. There are also climbing and evergreen species.
The Asian species also prefer acid soil and they will only produce flowers if the pH is low enough. Add sequestered iron, or place rusty iron impalements close by, or grow them under pines. All three make the soil more acid. This is why the best hydrangeas in England are found in acid pockets in the western half of Britain.
The American species are much more drought tolerant and they could be grown all across Britain in all types of garden. The flowers tend to be in a less showy spectrum of colour - creams, whites and pale-greens. But these are colours that glow in gloomy light and, as the flowers fade, shades of pink creep in. These American species grow happily on lime and even chalk.
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Hydrangea arborescens 'Annabelle'.
Hydrangea arborescens is an American native found from Louisiana to Florida and northwards to Iowa. There it survives the snowy winters and hot, dry summers of Iowa and will happily grow anywhere in Britain, regardless of rainfall or temperature. 'Annabelle' is the best form with flat-headed white flowers appearing from July. The green veining on the four "petals" (which are in fact long-lasting bracts) prevents 'Annabelle' from looking brash in summer sun.
This plant was discovered growing wild near Anna in Ohio, hence the name. It was launched in the mid-1970s by the Gulf Stream Nursery and is now widely available. These hydrangeas bloom on new wood so frost does not effect flowering. Cut down in late spring to the shooting buds.
From Madrona Nursery, has longer-lasting double flowers, although not quite as white.
The first pink arborescens developed by Dr Tom Ranney at North Carolina State University's Mountain Horticultural Crops Research Station.
A lovely cream-white form which produces flowers from green buds. Cool and fresh.
A floppy stemmed, cream starry double that’s fantastic in a container, but too brittle for most places in the garden.
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The oak-leaved hydrangea is another American species with large, lobed leaves that turn red in autumn. Heavy triangular heads of flower appear in late-summer to autumn and they are almost horizontal - so this is a good plant for a container, or for overhanging a wall. The two best known named forms are 'Snowflake' and 'Snow Queen' - both a cool white.
Hydrangea macrophylla 'Ami Pasquier'.
Flower colour of Hydrangea macrophylla depends on soil pH.
Maroon-coloured stems - pallid mophead flowers in pink or blue depending on soil pH.
Elegant white lacecap (1903).
Bright-rose to red lacecap.
Blue-budded pale grey-blue lacecap.
'Madame Emile Mouillière'
The finest white mophead for late use.
White starry lacecap.
'Générale Vicomtesse de Vibraye'
Earliest clear-blue mophead on acid soil, or rose pink on alkaline soil.
A black-stemmed blue hydrangea with a lacecap arrangement of flowers.
A striking deep-pink to wine-red lacecap. The name means Red Start.
‘Endless Summer Pink’
This is an easy pink mophead capable of flowering from basal shoots, so very good in a cooler garden.
A purplish-blue to dark pink mophead – again depending on soil.
Wiry small shrubs, perfect for small gardens, with good red autumn colour and smaller lacecap flowers. Ashwood Nurseries have the best collection.
A very old Japanese variety, often seen in their old paintings. Flowers in June, white flowers with few ray florets which age to pink. Upright growth to about 1 metre (3ft), with reddish foliage and stems later in the season. 1.5 m (5 ft).
(Japan) AGM 1992 (syn. Aigaku) A lovely small to medium-sized shrub covered with very shapely lacecap type heads. Flowers in early summer and repeats in autumn. Grow in sun or shade, pink or blue flowers according to soil type. Leaves change from green to reddish brown as the season progresses.
(Haworth – Booth pre 1970) Best grown as blue, this is a lovely dwarf shrub with a long flowering period. Rather uneven lacecap flowers with serrated edges to the florets and foliage which changes to reddish purple in autumn. Needs a sheltered spot to avoid spring frosts. 1.25m (4ft 1in).
Lovely golden foliage in spring which fades to green as the flowers develop. Upright growth, with many pale lacecap flowers.
(Chambers 1888) AGM 1992. A tall, slender lacecap with white florets, gradually changing to deep pink from the outer tips. The individual florets are unevenly shaped, serrated and very beautiful. They reverse with age displaying their deep crimson backs. This shrub improves with age, flowering from June until late October. 2m (6ft 7in).
A taller shrub with almost luminous medium sized lacecap flowers with both fertile and sterile flowers of rich blue. 1.5 to 2m (4ft - 6ft).
(syn. Var. Kiyusumensis) A plant with thin, wispy growth, but delicate lacecap flowers. The sterile florets are white and beautifully edged in rose-pink. Discovered originally on Mount Kiyosumi in Chiba Province, Japan, it has been used to produce some very striking cultivars.
A white flowered lacecap variety. Four or five ray flowers surrounding the white fertile flowers. The ray florets turn red in bright sunlight. A dwarf plant which needs some shelter to do well. 1m (3 ft).
(Haworth-Booth pre 1980) Neat little lacecaps with 6 to 10 sterile florets in shell pink or pale blue depending on soil. Fertile flowers are generally blue. A dwarfish shrub suitable for a patio container with a long flowering season and tidy habit. Up to 1m (3 ft).
(Japan) A free flowering white lacecap variety with green fertile flowers. Bushy and neat forming a small shrub. 1m (3 ft).
Large, clean lacecap blooms of shell pink, or mauve-blue on acid soil. Very free-flowering when well grown. Florets are irregular with one sepal larger than the rest.
(Foster 1992) Small pink or blue lacecap blooms in great profusion on medium sized bushes. Easily grown, hardy and very reliable for summer colour in the shrub border, with deep claret red foliage colours in autumn. Long lasting interest and one of the best serratas. 1m (3 ft).
Hydrangea paniculata 'Limelight'.
An oriental variety capable said to need lime-free soil but I also grow the following in my Cotswold garden quite happily. Best in shade in rich, well-fed soil. They make a late-summer feature and they are planted all over Battlestone Hill at RHS Wisley to great effect.
Lime-green to white lilac-shaped heads of flower. Medium to small sized shrub, subtle and lovely.
Very large shrub (up to 20 ft) with white flowers ageing to pink - loved by landscapers.
Huge bright-white heads - you either love it or hate it.
Much broader-based panicles of flower - white speckling to pink.
White flowers that darken to pink as the flowers mature. 'Confetti' can be grown in shade but produces more blooms in a sunnier position.
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