Outdoor Plant Profile: Hydrangeas
Hydrangeas are once again being seen in all the right gardens. For some of us they never went away
Longtime stalwarts of the traditional suburban garden, hydrangeas are enjoying a renaissance, their large blooms and beautiful foliage looking equally impressive as the centrepiece of contemporary courtyards or in large naturalistic swathes. Hydrangea lovers know there are lots of different species (about a hundred) to choose from.
Some will need more sun than others to flower well, some species will produce round blooms, while others are more pyramidal in shape. Leaf size and shape can vary also. There are even hydrangeas that can climb to impressive heights. Although most hydrangea are easy to grow, choose carefully to make sure yours will reach its full glorious potential in the conditions of your garden.
Some will need more sun than others to flower well, some species will produce round blooms, while others are more pyramidal in shape. Leaf size and shape can vary also. There are even hydrangeas that can climb to impressive heights. Although most hydrangea are easy to grow, choose carefully to make sure yours will reach its full glorious potential in the conditions of your garden.
Tip: The climber H. petiolaris, which has fragrant white flower clusters in late spring and summer, can also be pruned to grow as a shrub. If growing as a climber, make sure it has good support.
Signature traits
The most commonly grown hydrangea species are cultivars of Hydrangea macrophylla, famous for their large mop-head flowers in white, pink, red and blue. However Hydrangea paniculata cultivars, with their eye-catching, pyramidal flower heads, are very popular in gardens now too. Seen here is the white H. paniculata cultivar ‘Limelight’.
The most commonly grown hydrangea species are cultivars of Hydrangea macrophylla, famous for their large mop-head flowers in white, pink, red and blue. However Hydrangea paniculata cultivars, with their eye-catching, pyramidal flower heads, are very popular in gardens now too. Seen here is the white H. paniculata cultivar ‘Limelight’.
If you love interesting foliage, consider cultivars of the the oakleaf hydrangea species (Hydrangea quercifolia), which have distinctive deeply lobed, oak-like leaves that turn stunning orange, red or purple in autumn. Their blooms are more subtle than the showy mop-heads, but many hydrangea aficionados prefer their pyramidal creamy white flower clusters.
When to plant
Autumn and spring are the best times to plant most shrubs, including hydrangeas, as the soil is usually moist but not too cold, which would inhibit growth. In warmer areas you can plant hydrangeas during winter also. Avoid mid-summer planting as plants can dry out very quickly.
Where is it best positioned?
In a partly shaded spot (depending on the cultivar) with free-draining soil that has been augmented with plenty of organic matter before planting. Avoid planting your hydrangea where it is exposed to hot afternoon sun that can burn leaves and flowers. Morning sun is best.
Autumn and spring are the best times to plant most shrubs, including hydrangeas, as the soil is usually moist but not too cold, which would inhibit growth. In warmer areas you can plant hydrangeas during winter also. Avoid mid-summer planting as plants can dry out very quickly.
Where is it best positioned?
In a partly shaded spot (depending on the cultivar) with free-draining soil that has been augmented with plenty of organic matter before planting. Avoid planting your hydrangea where it is exposed to hot afternoon sun that can burn leaves and flowers. Morning sun is best.
How to plant
Dig a generous hole the same depth and twice as wide as the root ball of the plant. Make sure the main stem is not sitting below ground level as water may collect around the base and cause rotting. Add organic matter to the soil around the plant and mulch well.
When to water
Hydrangeas prefer some moisture in the soil (but not boggy) at all times, but will tolerate dryness when well established. Water well during dry weather.
Dig a generous hole the same depth and twice as wide as the root ball of the plant. Make sure the main stem is not sitting below ground level as water may collect around the base and cause rotting. Add organic matter to the soil around the plant and mulch well.
When to water
Hydrangeas prefer some moisture in the soil (but not boggy) at all times, but will tolerate dryness when well established. Water well during dry weather.
How to fertilise
Hydrangeas can cope with no feeding, but if you want bigger and better flowers, feed with a slow-release fertiliser at least once a year in the autumn. Some growers do it twice a year in spring and summer. Add plenty of organic matter also throughout the growing season (e.g. compost, animal manure or seaweed).
How to prune
Pruning should be done in autumn, or spring if it’s very cold in your area. For larger blooms and more compact plants cut back stems that have flowered to a pair of fat buds near the base. If you want to make sure flowers are as big as possible, remove some new shoots as well, leaving only the strong ones. To ensure the interior of shrubs have plenty of airflow, also remove spindly growth and stems that are crossing others. You can cut old, tired plants almost to ground level to rejuvenate.
Hydrangeas can cope with no feeding, but if you want bigger and better flowers, feed with a slow-release fertiliser at least once a year in the autumn. Some growers do it twice a year in spring and summer. Add plenty of organic matter also throughout the growing season (e.g. compost, animal manure or seaweed).
How to prune
Pruning should be done in autumn, or spring if it’s very cold in your area. For larger blooms and more compact plants cut back stems that have flowered to a pair of fat buds near the base. If you want to make sure flowers are as big as possible, remove some new shoots as well, leaving only the strong ones. To ensure the interior of shrubs have plenty of airflow, also remove spindly growth and stems that are crossing others. You can cut old, tired plants almost to ground level to rejuvenate.
Interesting fact
Hydrangeas generally produce blue flowers if planted in acidic soils (pH 4.5-5.5), and pink or red blooms in alkaline soils. It’s possible to make your hydrangea flowers more blue by adding aluminium sulphate every 7-14 days during the growing season. To make them more pink or red, sprinkle a few handfuls of lime on the soil at the same frequency, again during the growing season. Either treatment must be done well before flowering, and it may take a few years to see a change. It doesn’t usually work for white flowering hydrangeas.
Landscaping ideas
Hydrangeas make a lovely flowering informal hedge, particularly if planted against a plain wall or fence. They also look wonderful if planted in generous sweeps in larger gardens. Hydrangeas can also be used as a foundation plant for borders, with smaller perennials or shrubs in front. They do well in pots, but choose a smaller variety and make sure the container is a good size.
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Do you have hydrangeas in your home garden? Tell us your favourite thing about them in the Comments below.
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Hydrangeas generally produce blue flowers if planted in acidic soils (pH 4.5-5.5), and pink or red blooms in alkaline soils. It’s possible to make your hydrangea flowers more blue by adding aluminium sulphate every 7-14 days during the growing season. To make them more pink or red, sprinkle a few handfuls of lime on the soil at the same frequency, again during the growing season. Either treatment must be done well before flowering, and it may take a few years to see a change. It doesn’t usually work for white flowering hydrangeas.
Landscaping ideas
Hydrangeas make a lovely flowering informal hedge, particularly if planted against a plain wall or fence. They also look wonderful if planted in generous sweeps in larger gardens. Hydrangeas can also be used as a foundation plant for borders, with smaller perennials or shrubs in front. They do well in pots, but choose a smaller variety and make sure the container is a good size.
Tell us
Do you have hydrangeas in your home garden? Tell us your favourite thing about them in the Comments below.
More
Read more stories about gardening
Common and botanical name: Hydrangea
Origin: North and South America, Japan, China, Himalayas, Philippines and Indonesia
Size: Grown plants can range between 60-centimetre-tall dwarf shrubs to tall climbers such as Hydrangea petiolaris, which can reach more than seven metres in height.
Plant type: Deciduous hardy shrubs, trees and climbers