Hydrangea

Hydrangea

The most famous hydrangea is perhaps the Hydrangea macrophylla, but there are many different types of hydrangeas.

Below is a list of the most common species, with some more information per type:

Hydrangea macrophylla: the mophead hydrangea, bigleaf hydrangea and lacecap hydrangea

Hydrangea macrophylla: the mophead hydrangea, bigleaf hydrangea and lacecap hydrangea

Hydrangea macrophylla has large round flowerheads called mopheads or round, flat umbels called lacecaps. This species mainly grows in gardens. The flower buds usually emerge from wood that is two or several years old.

It is an easy, deciduous shrub, which blooms in late summer in different colours such as white, red, pink, deep pink, blue and purple. The plant is very hardy and its flowers are mostly spherical, although some species produce flat lacecaps. Hydrangea macrophylla prefers partial shade and soil that is not too dry.

These hydrangeas have large leaves with big surface areas, so they require ample irrigation. They do especially well in partial shade with some morning or evening sun, no midday sun and in filtered sunlight under a canopy that lets through some fine rays of light. Deep shade has a negative effect on their flower formation and will make the plant droop and fall open.

Hydrangea macrophylla Endless Summer, Forever & Ever, Magical, Music Collection offer several advantages. Unlike the ordinary Hydrangea macrophylla, they have a very long flowering period and they are also easy to prune.

Pruning

Leave the old flowers alone during the winter months, as they will protect the tender growth buds underneath from frost and cold wind.

Hydrangea macrophylla has two types of flowers: normal spherical flowers called mopheads and ‘Teller’ type flowers with flat umbels called lacecaps. The latter group requires little or no pruning. Only the weaker and dead branches should be cut. The mophead species call for a little more precision if we want to enjoy new flowers every year.

Last year’s spent flowers need to be deadheaded: cut back the stem of dead flower heads to the first strong, healthy bloom buds down from the faded bloom. The bloom buds are a thicker pair of flower buds on either side of the stem. Make sure not to prune any one-year branches, as they will most certainly have bloom buds on the head of the stem.

You can give the hydrangea macrophylla a good prune for a better bloom. Mophead hydrangeas start growing new bloom buds in late summer. If you were to cut back all the branches in spring, the plant will not have any flowers that summer. Still, it is advisable to rejuvenate adult mophead hydrangeas regularly.

Cut back about one third of the oldest, thickest stems to 5-10 cm from the surface. This type of pruning encourages the production of new replacement growth and ensures the flower size remains the same.

During pruning, you can already see the thick bloom buds from which future flowers will appear.

If an established hydrangea macrophylla has simply grown too large, you can hard prune it by cutting back all branches to 20-30 cm from the surface in spring. You should water the plant generously and add some compost or new garden soil. After this type of pruning, the hydrangea will produce new growth again, but not produce any new flowers until the following year.

When planting hydrangeas, always leave a 75 cm distance between plants.

Why are my blue hydrangea blooms turning pink?

A blue flowering hydrangea needs acidic soil to keep the flowers’ intense blue colour.

How can you make the soil more acidic?

A fair amount of black peat will make the soil more acidic, so make sure to add a lot of black peat to the plant hole when planting your blue hydrangea.

White mopheads are not affected by acidic or calcareous soil and not all pink hydrangeas will change colour in the same way. After treating the soil with black peat, pale pink mopheads will generally turn light blue.

There are two important conditions for beautiful blue hydrangeas:

  • The plant should be in acidic soil with a PH between 4 and 5.5.
  • The soil must contain enough iron or aluminium. Also bear in mind that in calcareous soil, calcium and iron combine, so the iron will no longer be available to the plant.

Use acidic soil for planting and give the plant a dose of aluminium sulphate (alum) in late August and mid-March. You can dissolve aluminium sulphate in water or simply scatter it around the plant. Our range also includes a special soil improver for rhododendrons and hydrangeas.

Hydrangea macrophylla – Hydrangea/Big leaf hydrangea

  • Position: full sun/partial shade
  • Soil: moist/well drained soil
  • Flowering period: July – September
  • Height: 1-2 m
  • Evergreen: no
  • Hardy: yes

Hydrangea paniculata or panicle hydrangea

The panicle hydrangea gets its name from its large, cone-shaped panicles. When the plumes start growing in July, they have a yellow-green colour, which then turns into a gorgeous cream. When autumn approaches, the flower panicles gradually take on pale pink tones.

Again there are different cultivars, the most famous of which is the Hydrangea paniculata ‘Limelight’. The plant reaches a height of 1.50 to 2 m and its panicles can be 15 to 30 cm long.

Hydrangea p. ‘Little Lime’ will stay closer to the ground (height 1.10 m).

Hydrangea p. ‘Pinky Winky’ also has the advantage that it does not grow very high (height 1 to 1.40 m). This cultivar’s flower stalks have a dark red colour. At the end of the season, the flower panicles turn a deep pink/red.

The plume-shaped flowers of the Hydrangea p. ‘Vanille Fraise’ also turn pink/red, but the colour is not as deep as the Hydrangea p. ‘Pinky Winky’, the plant does grow up to 2 metres tall.

Hydrangea p. ‘Grandiflora’ has a broad, vertical habit. It reaches a height of 2.50 m and a width of 1.50 m.

Hydrangea paniculata ‘Wim’s Red’ is a panicle hydrangea with upright branches and very extraordinary, plume-like flowers. Flowering starts very early in May/June with white flower umbels. These then change to a light pink and by September they are a deep burgundy. The more sun they get, the more intense their colour will be. The young branches are also decorative in the spring: they start off red and combine beautifully with the dark green leaves.

Pruning

All types of panicle hydrangea can be cut back to 20-30 cm from the ground in March (before the buds start sprouting). All young plants do not need any pruning the first two years.

Planting

When you are planting Hydrangea macrophylla, keep a distance of 75 cm between plants.

Panicle hydrangea can be planted from March to mid-October. During this period, the soil is warm enough for the plants to take root.

Care

Some panicle hydrangea cultivars may droop during the season, particularly Hydrangea p. ‘Grandiflora’. You can tie them up to offer support. The harder you prune back panicle hydrangeas, the bigger their cone-shaped flowers will grow. If you cut back less – to 60 cm from the ground, for example – the flowers will not be so large and heavy and drooping should be less of a problem. You might even consider not pruning your panicle hydrangea. Panicle hydrangeas that have not been cut back will still produce flowers, only smaller ones.

We regularly carry the above types of panicle hydrangeas as well as some lesser-known cultivars. If we do not carry a particular type in our range, we can look for it at the various fairs that we attend.

  • Position: full sun/partial shade
  • Soil: moist, well-drained soil
  • Flowering time: July-September
  • Height: depending on the type
  • Evergreen: no
  • Hardy: yes

Hydrangea arborescens

Hydrangea arborescens is a strong, deciduous shrub that is particularly appreciated for its spectacular flowers.

A very popular species is Hydrangea arborescens ‘Annabelle’, which grows about 1.50 m tall and produces huge, round 30 cm mopheads in July-September with creamy white flowers. As autumn approaches, the flowers turn a lemon yellow.

Hydrangea arborescens ‘Incrediball’ (‘Strong Annabelle’) is an improved version of the Annabelle. It has the same large white flowers, but they have stronger, firmer stalks. This cultivar grows about 1.20 – 1.50 m high and 1.50 m wide.

Hydrangea arborescens ‘Invincibelle’, also referred to as hydrangea arborescens ‘Pink Annabelle’, is pink flowering. It has the same features as the Annabelle, but its flowers are somewhat smaller – about 20 cm – and the plant’s height usually does not exceed 1 m.

Pruning

All these types can be pruned to 20-30 cm from the ground in March.

If at the end of the season the Annabelle no longer looks attractive because the rain and wind have completely flattened the leaves, you can also cut them all the way back to 20-30 cm in late autumn. The plant will sprout again without any problems in the spring. All young Hydrangea arborescens, including Hydrangea arborescens ‘Annabelle’, ‘Incrediball’ and ‘Pink Annabelle’, do not require any pruning the first two years.

Planting

Keep a 75 cm distance between plants when planting Hydrangea arborescens.

You can plant these hydrangeas from March to mid-October, when the soil is warm enough for the plants to take root.

Care

The harder you cut back Annabelles, the bigger the flowers will be. Less drastic pruning – down to 60 cm from the ground, for example – will make the mopheads less heavy and large, so they will hang less. You might even want to consider not cutting back your Annabelles at all. Annabelles that have not been pruned will still produce flowers, only smaller ones. You can also support Annabelles to help them stay upright.

  • Position: full sun/partial shade
  • Soil: moist, well-drained soil
  • Height: 1 – 1.50 m.
  • Flowering period: July – September
  • Evergreen: deciduous
  • Hardy: yes

Hydrangea petiolaris or climbing hydrangea

The climbing hydrangea has a white, flat habit and flowers on its side shoots.

Hydrangea petiolaris is a deciduous climber. Over the years, it can easily cover a complete high wall or fence. It is a slow grower and it does take a while before a wall is completely covered. It produces flat umbels with small, white flowers from June to August. Its leaves are a beautiful dark green and almost heart-shaped. The climbing hydrangea can grow in partial shade, but will thrive better with richer blooms in a sunny spot.

Pruning

Note that the climbing hydrangea has two types of branches:

  1. Climbing branches with aerial stem roots clinging to the wall
  2. Lateral branches growing from the climbing branches. The lateral branches often grow away from the wall and are best pruned to 15 cm from the climbing branch after flowering. Do not cut back all the side branches at once, because that will prevent the climbing hydrangea from producing flowers the following year. It is better is to cut back only some side branches here and there every year. The best time for pruning is in the summer after flowering.

Care

In the beginning, the young plants need some support. Put up some garden twine and tie in the young shoots, which will automatically climb the wall later.

Water young climbing hydrangeas generously and frequently during dry spells.

  • Position: full sun/partial shade
  • Soil: fertile, well-drained soil
  • Flowering period: June – August
  • Height/width: 15 m/3-5 m
  • Evergreen: deciduous
  • Hardy: yes

Hydrangea quercifolia or oakleaf hydrangea

The leaves of the oakleaf hydrangea are shaped like the leaves of an oak, but they are about 20 cm long and almost as wide, so they are quite a bit larger. The oakleaf hydrangea’s white plumes emerge from two-year wood. The species can easily reach 2 m in height.

The hydrangea quercifolia has some of the most beautiful flower and autumn colours of all types of hydrangeas.

It needs little or no pruning. Just remove dead or damaged branches.

Hydrangea serrata or mountain hydrangea

The Hydrangea serrata is very similar to the normal Hydrangea macrophylla, but it has thinner branches and its flower buds can withstand the spring frost slightly better.

It is an exceptionally elegant and hardy hydrangea with panicle-shaped flowers. If the serrata’s leaves get enough sunshine, they will turn a beautiful red colour. The leaves are usually also finer and more pointed. The plant tends to be about 30 cm shorter than macrophyllas. Most hydrangeas serratas bloom several weeks earlier than the macrophylla types. Most serrata species are lacecap types that require little or no pruning. We do not always have them in our range.

Hydrangea aspera or rough-leaved hydrangea

The rough-leaved hydrangea blossoms with large, flat umbels in July – August. It is characterised by its large, grey, soft, hairy leaves and its peeling bark. The rough-leaved hydrangea requires little or no pruning. Simply remove any dead wood and weak branches.

Most hydrangeas bloom for 2 to 3 months. Their beautiful flowers can last a long time. The flowering period varies from species to species.

All hydrangeas hate dry weather and should be watered generously in case of drought, particularly in spring and summer. It is better to give them a large amount of water all at once than to give them a little water every now and then.

Sometimes hydrangea shrubs get a little bare near the base during the flowering season. The leaves may also turn yellow. Baldness and yellow leaves are nearly always caused by drought and too little water.

The various groups often require a different amount of pruning and a different type of pruning.