How to Grow Hydrangeas

Hydrangea are a deciduous, summer flowering shrub with large, showy flowers.

Hydrangea are easy to grow and require only minimal pruning. They are not fussy about soil types and most, including the climbing Hydrangea, will grow in partial shade. Hydrangea are large shrubs from  1.5m - 3m (3-10ft) requiring a fair amount of growing space.

 Hydrangea have large showy flower heads, predominately flowering in pink, mauve, blue, cream and white, and multicoloured such as Hydrangea macrophylla 'Merveille'.  Some varieties of Hydrangea change colour depending on the pH of the soil, acid or alkaline.  This applies to H. macrophylla, the mopheads and lacecaps varieties, where the flowers are blue when grown in an acid soil and pink if planted in alkaline soil; the white flowers are unaffected.

There are also some varieties of Hydrangea which have scented blooms, such as Hydrangea paniculata 'Wim's Red' and also some compact varieties H. panciulata Little lime ('Jane') and Hydrangea with beautiful delicate colours such as pink turning to white as in Hydrangea paniculata Vanille Fraise ('Renhy')

The range of Hydrangea is wide and varied, and many are illustrated below and also on Pinterest board.  When selecting a Hydrangea for the garden it is best to check out the variety carefully, some will grow to around 3m which is a bit large for the average garden , but there are Macrophylla varieties which reach around 1.5m. a useful size for most gardens.

How to Plant Hydrangea

Hydrangea are a woodland plant with a preference for moist but well-drained soil with some sun and dappled shade or semishade. As a woodland plant, Hydrangea will thrive in the cooler part of the garden and is best planted away from the hot afternoon sun.  As always, it is a question of the right plant right place, which means avoid planting where there is hot afternoon sun or cold easterly winds. 

There is also a climbing form of Hydrangea, H. petiorlaris, which will tolerate a higher degree of shade and can be useful to grow up a shady wall. This is a lovely climber, relatively fast growing with beautiful flowers in the spring. I have seen grown to great effect on a large semi shaded wall where it was left to grow unchecked and formed a mass of white flowers in the spring. It is self-supporting but needs a reasonably large space. For images and information about growing the Climbing Hydrangea click here.

Having decided where to plant your Hydrangea, dig a hole at least 3 times the size of the root ball and deep enough so the level of the compost in its container is at soil level. Do not plant Hydrangea too deep, keep the level the same and water the hole well before planting. Hydrangea do not thrive on dry soil and will benefit from a mulch to retain moisture. Make sure the shrub is firm and well watered.

Growing Hydrangea in containers

Hydrangea are not ideal for growing in containers because they can get large, and their roots quickly expand into the container. In addition, Hydrangea do not do well when grow in dry soil or dry out. All plants grown in containers are at risk of drying out because of the relatively small growing area.

Whilst many Hydrangeas do get large,  up to 2.5m + new varieties are being developed all the time and there are now many smaller patio varieties which are more suitable for growing in a container.  A search for small/compact/patio Hydrangeas will produce a raft of results. If space is a premium Hydrangea can be container grown, most important is to plant into a large container which is placed out of the hot sun and kept well watered.

Four of the most common types of Hydrangea

  • Hydrangea-paniculata-310x-240
  • hydrangea-paniculata-fading-blooms-310x240

Hydrangea Paniculata

This is Hydrangea Paniculata which is a large variety growing up to 7 x 5m. It flowers best if regularly pruned in the spring, see below. It flowers in the late summer, producing white or cream flowers. 

As its name suggests, the flowers are cone shaped and appear in late summer early autumn changing colour as they fade. 

  • Climbing hydrangea 310
  • climbing hydrangea improved 310

Hydrangea Petiolaris

This is the climbing form of Hydrangea variety growing up to 15m. It will easily cover a wall. It rewards with fantastic fresh green foliage in spring, and lovely delicate flowers in early summer.

It is spring flowering, and should be pruned after it has flowered.  A vigorous, deciduous climber which is fully hardy, self clinging and shade tolerant.

  • pink Lacecap Hydrangea 310
  • blue-hydrangea-macrophhylla 310

    Hydrangea macrophylla

    This group includes both Mopheads and Lacecaps, which are the most commonly grown and have large showy blooms.

    Mopheads have rounded flower heads and Lacecaps flattened flower heads.

    This is also the group of Hydrangeas where the flower colour is effected by the soil type. Blue blooms on acid soil and Pink on alkaline.

    Hydrangea arborescens

    Hydrangea arborescens

     A rounded shaped shrub which has large flowers, white, which appear in the summer.

    Illustrated is H. arborescens 'Annabelle' which has large flowers around 20cms across. It has multiple blooms which turn from white green to pure white.

    When and How to Prune Hydrangea

    You need to decide which type of Hydrangea you have to know how and when to prune it. Hopefully, the images and descriptions above may help. H. Mophead and Lacecaps flower on old wood (what does this mean?) and they are pruned lightly in spring. Just cut back a few cm down to a bud, do not prune hard although you can remove spindly, weak growth. The image drawing below shows the light prune required for Mopheads and Lacecaps.

    Hydrangea paniculata, distinguishable by its cone shaped blooms, flowers on the current year's growth (wood) and is pruned much harder in late winter/early spring. This means all the flowers are produced on new stems which grow in the same year as flowering. When you prune H. paniculata, cut back to a framework to enable the shrub to make new growth. 

    Pruning is not essential both Mophead and Lacecap will flower without pruning. The benefit of pruning is to keep the shrub in shape and pruning can improve flowering. 

    Pruning in late winter or early spring has the risk of frost. If there is a severe frost, it can damage the new growth, and it may be necessary to prune again back further to a pair of healthy buds. Also on older shrubs remove a few, 2/3 older stems from the based which will encourage new growth later in the spring.  

     

    How to prune Hydrangea with text

    For Lacecap Hydrangea a light prune in February to remove the top of the stems with last season's flower head in place and cut down to just above a green bud which will be showing by now. Do not prune harder, or lower, to do so is a mistake which can prevent the Hydrangea flowering later in the summer.

    A climbing Hydrangea should be pruned immediately after flowering to restrict its growth, cutting back long shoots. It can be pruned harder if needed, but if you are pruning hard, it is best to stagger over more than one year because if it is pruned hard all at once, there may be significantly fewer flowers the next year.

    Hydrangea paniculata and H. arborescens need more attentive pruning, (which may be why they are less popular.) Each spring prune back to a framework which means cutting back stems to a pair of buds. These varieties flower best if pruned harder so can be cut back to the lowest pair of buds which may result in the plant, post pruning, only being 25cms but you can, of course, leave several buds on and prune less hard.

    The easiest Hydrangea to grow are the Lacecaps and Mopheads as you can simply remove the old flower heads in the spring, cutting down to a pair of buds and that's it.

    green wheelbarrow

    Hydrangea is a green wheelbarrow shrub being easy to grow and tolerant of most conditions.

    Last updated 09.10.2021