Hydrangea macrophylla types are the main garden Hydrangeas grown in the UK. The group is split into two distinct flower types The Mopheads and the Lacecaps. For the purpose of this page, they can be treated in the same manner as far as pruning is concerned. Both Mophead and Lacecap Hydrangeas benefit from pruning to keep shape and size under control, but neither actually Need pruning.
If they are to be pruned, then the information and illustrations below will guide you through the very simple pruning operation. Do it in the right manner, and at the right time of year, and you should have a good succession of blooms and new shoots. Un-pruned Hydrangeas in this group tend to lose flower size as the years go by.
The important thing to know, is that as they are mid to late summer flowering, they produce flower on shoots that were made in the previous year. From these older shoots, the current years grow will start which are the actual flower bearing stems.
As an example, if you were to cut this type of Hydrangea macrophylla down to ground level in the late spring or early summer, it would produce masses of new shoots quite soon, but they will be the stems from which next year's flowers will grow. These new shoots as healthy as they look will not flower this year.
It is normal to leave the faded flower heads on the plant throughout the winter. They give added interest in the autumn, and protect the new buds below from severe frost damage.
Hydrangea serrata Bluebird - Image Above. A choice and popular lace cap variety of Hydrangea that falls within the method of pruning outlined below.
In early spring, simply prune off last season's flower heads to about the first pair of healthy buds below the old flower head. You will be cutting back into the stem that was produced by the plant last year now it is this year's flower bearing shoot. At the time of this pruning, there will probably be some shoots emerging from the dormant buds. That is normal you can still cut to just above a good new pair of shoots if this has started. Don't be tempted to cut further down the stem. 4-6in from the old flower head is about right.
With older bushes, it would be a good idea to prune one or two of the main stems down to near ground level to encourage new growth from the base of the plant. This ensures continuous supply of healthy stems and usually results in larger Hydrangea flowers.
When doing this rejuvenation pruning, take out shoots evenly around the mature bush to ensure a uniform habit of growth. It is a good idea when doing this, to take out the weakest most spindly stems. They can then start life again with new vigour - normally improving into sturdy youths!
Detail diagram of how to cut back the old flower truss The pruned Hydrangea picture below, shows the hydrangea bush in the top sketch after pruning to open out and remove weak growth.
For most deciduous shrubs that flower in mid to late summer on growth made in the previous year, which included the hydrangeas above, the pruning method is the same.
Hydrangeas are one of the most popular of all garden shrubs with very showy flowers and large attractive leaves. The fact that they are so very easy to grow, adaptable to most soil and garden situations, makes them the ideal choice for inclusion in a shrub bed or border. They can also be featured as a stand-alone specimen in the middle of a lawn bed. Hydrangeas also make good container plants. There is also a good climbing version of the Hydrangea family.
Another point in the favour of all Hydrangeas is that they all have reasonable autumn foliage colour – heightened by the fact that most have large leaves.
Then to take us through the winter, there are superb seedheads – about the same size as the preceding flowers – which will last through until spring. The Mophead Hydrangeas have a better show in this respect. Many a Christmas display is set off with an arrangement of metallic sprayed seedheads.
Florists also make good use of Hydrangeas as potted houseplants. These are the same as the garden hydrangeas, but grown differently. After use indoors, they can be planted out in the garden or outside container.
The ease of growing Hydrangeas is highlighted by the rarity of help questions my mailbox. It is one of the easiest and rewarding of shrub with very few problems. The main question I get for help advice, is how to turn the flowers blue!
Hydrangeas can be conveniently split into a few groups – all of the plants in each group being happy with the same cultural requirements – One size fits all – almost!
The main garden Hydrangea shrubs are within the Hydrangea macrophylla group. Hydrangea macrophylla types are split into the common mop-head types or Lace-Caps.
The Mopheads – generally classed as ‘Hortensia Hydrangeas’ have round globular blooms of varying sizes, which are made up of masses of smaller florets. The individual florets are male – therefore not fertile – and are blessed with the groups wide range of colors ranging from pure white, through light pink to deep red. There are also some violet/purple types. The much sought-after blue flowers are also in the is group – of which, more below!
Some of the Mophead Hydrangeas are almost as big as a football, but generally around 4-6in across (10-15cm). Others tend to be 'domed' rather than fully spherical globes.
The Lacecap group of Hydrangea macrophylla has flat blooms with the outer surrounds of showy florets - which are the fertile female flowers – giving them the worthy description of ‘Lacecaps’. These female florets surround the central cluster of the smaller male flowers – for obvious reasons!
The flower range is as with the Mopheads, but with some interesting bi-colour effects brought about by the difference in some, of the female and male flowers; the darker centre being normally surrounded by the lighter coloured female flowers.
Both Mophead and Lacecap types within the H. macrophylla group have the same cultural requirements. Full sun is perfect, with dappled shade coming also acceptable. Though they prefer a slightly moist soil, I have seen and photographed many fine specimens in dry soil areas.
They are happy in a wide range of soil types – other than heavy clay – but do best in a fertile, well drained soil that does not become waterlogged in winter. Annual mulching of organic material is beneficial, both for general plant health, but also because it will help to regulate the soil’s ph level. High lime content – such as on chalky soils – or near and old wall that had lime mortar, will probably lead to a lightening of leaf colour which signifies like induced chlorosis. It will be virtually impossible to grow for the desired blue flowers in this situation.
These Hydrangeas are reasonably tolerant of dry weather conditions, but do tend to look rather sorry for themselves with their drooping leaves in the driest conditions. Drooping foliage is also apparent on hot sunny days. Apply a much to keep the soils as moist as possible. Give a good soaking around the root zone - not spray all over the foliage or flowers
There are several other Hydrangeas that can lay claim to either being Mophead or Lacecap. Two of such would find their way into any garden of mine, conveniently being one of each.
Hydrangea preziosa would fill the gap as far at Mopheads are concerned, with its bright deepest pink flowers – nay, red - as a basis, but planted in a non alkaline soil, the flower colour can be mauve or varied shades of blue. Upright growing, but very ‘dapper’, it is great in a container!
Hydrangea villosa just about makes it as a lacecap with somewhat sparse surround of florets. Slightly spreading – unless pruned otherwise – it has narrow lance like leaves - very smooth and velvet textured - which are good contrast to the blue-purple inner flower head which resembles an upturned broccoli head – but much more decorative. Great contrast on the flowerhead with white florets surrounding in contrast to the purple. It is later flowering than most on this page, so just in time to brighten up our early winter.
Over the years I have had requests for help in diagnosing a a ‘disease’ affecting Hydrangea stems. The bark positively flakes like brown tissue paper on some varieties. Not a disease; it happens – especially on older un-pruned stems.
Not all varieties have this added attraction, so will be outlined in the accompanying lists.
How to Turn Hydrangeas Blue - Applies only to Hydrangea macrophylla types.Pruning Hydrangea Paniculata types - also H. Arborescens.
Cornus alba, stolonifera and sanguinea