Hydrangea

How To Grow Heavenly Hydrangeas

Hydrangeas give a huge blast of colour to the summer and autumn garden

Hydrangeas are one of the mainstays of a summer garden, giving a huge display of colour which lasts well into autumn. Many of them also give good autumn leaf colour. Even the flower heads left over winter add a sculptural beauty to the garden, and can be used to make natural Christmas decorations. They come in a huge range of colours from white to deepest rose pink. The flowers can be huge and extravagant or delicate and lacy. Even if you don’t have a large garden they can be grown in pots on the patio. There are two main types; the mop head which is a large round ball and the lace-cap which has a border of large petalled flowers with tiny flowers inside.

Site

They need lots of sun and moisture, but not a boggy site. They can cope with the hot midday sun but only if there is sufficient moisture available. This shouldn’t be a problem with an older established plant in a moisture retentive soil. If planted in the shade they will not bloom very well. When planting in the garden make sure it will have plenty of room, about 120cm x 120cm (4’ x 4’) otherwise it will shade out other plants. Make sure the site does not get cold winds as they will damage the new growth in spring.

How to grow

The best time to plant is early spring but not if the ground is too cold or if frost is forecast. They can be planted in summer but you must make sure that they are kept well watered; if the weather is hot it will need watering every day. They need a well-drained but moisture retentive soil. Prepare the planting hole by adding organic compost or composted garden waste and a handful of blood, fish and bone. Plant to the same level as it is in the pot. If you have to move one do it when it is dormant in winter or very early spring before it starts to put on any growth. Feed with a balanced fertiliser, such as Osmacote slow release, in spring or early summer. If the soil is good and rich you probably don’t need to feed as there will be sufficient food in the soil for several years. If the flowers become small then it probably needs feeding. Do not feed in late summer or autumn as it will put on a spurt of growth which will freeze in winter and affect the growth in the following summer. If it fails to flower or only has a few flowers it could be caused by pruning too late in spring, too shady a spot or too much fertiliser with a high nitrogen content.

Hydrangea Magical Four Seasons 'Jade'

Hydrangea Magical Four Seasons 'Jade' 

Pruning

Prune the climbing Hydrangea anomala petiolaris and Hydrangea seemanii after flowering. Prune the shrub Hydrangeas in early spring; remove last years flower heads and cut back to a healthy pair of buds. If the plant becomes too large and woody it can be cut back to the base, although this results in no flowers for that season. Leaving the dead heads on the plant over winter provides protection when the new shoots emerge in spring.

Colour

The soil pH affects the colour of Hydrangeas. If it has blue flowers it needs an acidic soil. A blueing compound is available in garden centres and this will enhance the blue colour of the flowers. If your soil is limey then a blue Hydrangea would be better planted in a container. White or green tinged flowers are not affected by the soil acidity. Pink flowers can be enhanced by a top dressing of lime or chalk.

Hydrangea macrophylla 'Black Steel'

Hydrangea macrophylla 'Black Steel'

Growing in a container

If you do not have the right soil pH for the particular coloured plant then you need to grow it in a container. If the plant is blue use ericaceous compost; if pink use organic peat free compost with a little lime or chalk added. Remember to add a good layer of crocks to the bottom of the pot to aid drainage and stop the hole in the pot blocking up with silt. Growing a Hydrangea in a pot is quite labour intensive as they dry out easily when the weather is warm, so make sure you keep it well watered. They soon fill the pot so you will need to re-pot regularly.

Hydrangea Magical four Seasons 'Noblesse'

Hydrangea Magical Four Seasons 'Noblesse'

Recommended varieties

Petiolaris; a climbing variety suitable for a north facing wall, which is smothered in white flowers.
Arborescens ‘Annabelle’; a mophead with huge white flowers, up to 30cm (12”) across.
'Love You Kiss'; a lace-cap with white flowers edged with red.
Macrophylla ‘Endless Summer’; a mop head with large flowers; pink on alkaline soil and blue on acidic soil.
Macrophylla ‘Limelight’; huge slightly conical blooms which change colour though the season; starting with lime, then cream, then pink and finally turning deep pink in autumn.
Macrophylla ‘Silver Dollar’; huge creamy white conical blooms which flush pink as they age.
Macrophylla ‘Black Steel’; large dark rose pink blooms; dark, almost black, stems and very dark leaves.
Macrophylla ‘Magical Four Seasons’; a range of colours often with bi-coloured petals. Notable for changing colour through the seasons. ‘Magical Sapphire’ is dark pink. ‘Magical Harmony’ is deep blue edged with green. ‘Magical Jade’ is a mixture of pink, green and cream. ‘Magical Noblesse’ starts green then progresses to green with a white centre which then turns green with a pink and white centre and finally in autumn it is green with a pink tinge.

Angela Slater
Daughter of a farmer and market gardener so have always had a connection with the outdoors, whether it was keeping animals or producing fruit, vegetables and cut flowers. Along with my work at Hayes Garden World I also have a smallholding, mainly breeding rare breed pigs. I gained an HND and BSc in Conservation and Environmental Land Management, as a result I am an ardent environmentalist and have a keen interest in environmentally friendly gardening. In my time at Hayes I worked for several years in the Outdoor Plant and Houseplant areas