You can beautifully green bare walls, bare house walls, and other unsightly corners in the garden with the help of climbing hydrangea.
Within a few years, a single small bush develops into a climbing plant up to 50 ft (15 m) high and 16 ft (5 m) wide.
It not only makes gray concrete disappear behind a dense green wall. The creamy white, sweet-smelling corymb flowers also attract numerous insects, including butterflies in particular.
Origin and Distribution
The lushly growing climbing hydrangea (Hydrangea petiolaris) is at home in the shady and moist cloud forests of Japan, Korea, and Taiwan.
However, this species of the hydrangea family (Hydrangeaceae) has been planted in other parts of the world for many decades. It is used primarily as decorative greenery for facades, walls, fences, or pergolas.
As the name suggests, Climbing Hydrangea is a self-climbing vine used mainly for greening walls, walls, fences, and pergolas.
In this posture, the strong green foliage leaves as well as the very numerous appearing creamy white corymb flowers come into their own wonderfully.
Climbing hydrangeas work best when planted in solitary, especially since the species takes up a lot of space.
Alternatively, you can plant them together with clematis, which requires similar growing and site conditions. The colorful clematis flowers complement the white and green colors of the climbing hydrangea.
Appearance and Growth
Climbing hydrangea develops its adventitious roots exclusively on the side of its numerous shoots facing away from the light, which can develop into thick branches over time.
With the help of these climbing roots, the self-climber reaches growth heights of 19 to 23 ft (6 to 7 m) on average. But it can grow up to 50 ft (15 m) in favorable conditions.
It takes a while to reach this height, however. With about 6 to 8 inches (15 to 20 cm) of new growth per year, the plant is one of the rather slow-growing species. But a suitable location and mild winter certainly increase growth speed.
In the first few years, you should provide the climbing hydrangea with a climbing aid. This makes it easier for the plant to find proper support on walls or fences.
But be careful: the penetrating adventitious roots can severely damage plastered surfaces as well as concrete walls, such as those commonly found on house walls.
Therefore, it is better to install the climbing frame at a distance of about 4 inches (10 cm) from the wall. Solid stone walls, on the other hand, are not at risk.
If there is no climbing opportunity, the species develops into a hemispherical and broad shrub. It will then only grow up to 7 ft (2 m) high.
Typically, the reddish-brown bark on older branches and twigs peels off. So it is not a symptom of a disease or pest infestation, as is often assumed.
The glossy green leaves of the climbing hydrangea strongly resemble those of the related hortensia. They are long-stalked, ovate to roundish in shape, and can grow up to 4 inches (10 cm) long.
The species is deciduous, and in addition, the foliage of most varieties turns bright yellow in the fall.
However, some newer cultivars are now considered evergreen and retain their dense foliage during the winter. These varieties do not shed their dense foliage until the following spring before new shoots appear.
Flowers and Flowering Time
Don’t be surprised if your climbing hydrangea, planted only a few months ago, doesn’t want to bloom yet. This behavior is completely normal.
The species only shows its flat, up to 10 inches (25 cm) wide corymbs for the first time after a standing time of at least five to eight years.
These consist of inconspicuous, fertile inner flowers and a wreath of creamy white, sterile show flowers.
The numerous, sweet-smelling flower plates appear between May and July. They serve as valuable pasture for numerous insects – especially butterflies, bees, and bumblebees.
Subsequently, the plant forms capsule fruits.
Like all hydrangeas, climbing hydrangea is poisonous, especially to pets such as dogs, cats, small rodents, as well as birds.
Make sure your pets do not eat from the plant, as the toxins it contains can cause stomach and intestinal problems as well as circulatory problems. Small children are also at risk.
Which Location is Suitable for Climbing Hydrangea?
Climbing hydrangea is suitable planting for semi-shady to shady locations and perfectly greening, for example, even north walls.
The forest plant does not tolerate direct sunlight. This would burn both the leaves and the flowers. A wind-protected place is also important.
In principle, it is also possible to keep it in a sufficiently large container on the balcony or terrace.
But you should be careful in rented apartments. Here, the culture of self-climbing vines is often prohibited, because the adventitious roots can cause damage to plaster and walls.
In addition to a semi-shady or shady spot in the garden, the climbing hydrangea also needs fresh to moist soil with an acidic to neutral pH.
But be careful: Although the plant feels well on a fresh substrate it still does not tolerate waterlogging. Therefore, if possible, do not plant the species at the bottom of a slope or in a hollow.
Here the water collects and eventually causes rotting diseases. Also, avoid calcareous soil such as along the plastered wall of a house as the plant is not tolerant of lime.
Rule of thumb: The substrate should be the moister the brighter the location for the climbing hydrangea is.
Planting Climbing Hydrangea Correctly
The best time to plant climbing hydrangea is on a mild day between late March and late May.
Submerge the dry root ball in a bucket of water so that the fine roots can soak up moisture. Meanwhile, dig a generous planting hole that should be about twice as wide and deep as the root ball.
Slightly loosen the sides as well as the soil and mix the excavated soil with compost and/or rhododendron soil.
Now plant the climbing hydrangea, water it well, and then mulch the root area. The mulch layer prevents the soil from drying out and thus helps the plant to take root.
The climbing hydrangea itself develops adventitious climbing roots, with the help of which it climbs not too smooth surfaces. In this respect, it is similar to ivy.
But in its young years, it benefits from support in the form of a climbing aid. On this, you can direct the fresh shoots in the desired direction or keep the plant away from plastered or otherwise porous surfaces.
On a fence or pergola, in turn, you can attach the branches with the help of floral wires.
Watering and Fertilizing Climbing Hydrangea
Climbing hydrangeas have a fairly high water requirement. You should therefore keep them evenly moist.
On the other hand, you should avoid waterlogging. Therefore, you should plant them in compacted soil only with additional drainage.
A subsoil that is too dry will cause the plant to shed foliage and flowers.
In the spring, provide the plant with mature leaf compost and horn meal or shavings. If needed – such as lack of growth or chlorosis – apply additional hydrangea or rhododendron fertilizer.
On the other hand, fertilizing with blue fertilizer, which gardeners often use, is not advisable.
Pruning Climbing Hydrangea Correctly
Especially young specimens of climbing hydrangea do not yet need pruning, because they grow very slowly anyway.
However, you can cut the shoots back by about a third directly after planting to achieve stronger branching.
For older plants, it is best to proceed as follows:
- Thin out the plant as needed.
- Remove dried, dead and frostbitten branches at the base. Cut these already in spring.
- Otherwise cut climbing hydrangea immediately after flowering because the flowers of the following year are formed already in autumn.
- Use sharp and clean secateurs or rose shears.
- Always cut just above a bud.
- Cuts into the perennial wood are possible.
- Observe growth behavior and cut back if necessary. For example, if the plant threatens to overgrow windows.
If possible, plant the climbing hydrangea so that the plant can spread according to its nature and does not have to be limited in its growth by frequent pruning.
Propagating Climbing Hydrangea
In early summer, climbing hydrangeas can be propagated very well by cuttings or ground-hugging cuttings. Cut these from the mother plant only after successful rooting.
It is best to cut only slightly woody, young and flowerless branches between June and July. Plant them individually in pots with a growing medium and keep the substrate slightly moist.
Alternatively, propagation is possible by so-called hardwood cuttings. Cut the hardwood cuttings in winter.
Wintering Climbing Hydrangea
Climbing hydrangeas are winter-hardy. They can tolerate temperatures of down to -30 °F (-34 °C).
They only require light winter protection as freshly planted young plants, for example in the form of a cover with brushwood or jute.
Diseases and Pests
No plant is completely immune to disease, including, of course, the otherwise very hardy climbing hydrangea.
Especially powdery mildew diseases give it a hard time. in locations with too high a pH value, chlorosis also develops quickly.
As far as pests are concerned, it is mainly aphids that find their way in.
Species and Varieties
There are quite a few pretty cultivars of the species Hydrangea petiolaris. But they are widely grown especially in Great Britain.
You can sometimes find such pretty varieties as:
- Cordifolia: Dwarf form growing only up to 10 ft (3 m) high with creamy white flowers.
- Miranda: Striking yellow-green variegated foliage and large creamy white flowers.
- Semiola: Evergreen new variety with beautiful white flowers.
- Silver Lining: Low-growing variety with a maximum height of 7 ft (2 m) and striking white-green variegated foliage. This variety is very suitable for container planting.
In addition to the climbing hydrangea Hydrangea petiolaris, the closely related as well as quite similar looking Japanese hydrangea vine (Hydrangea hydrangeoides) is also popular for planting in the garden.