How to grow climbing hydrangeas

Choosing a climbing hydrangea

Climbing hydrangeas are very useful climbers for covering shady walls of fences and the attractive white flowers in early summer are a welcome bonus.  They can also be also let to climb into medium to large trees. The deciduous Hydrangea anomala subsp. petiolaris is hardy and easy to grow.  Evergreen climbing hydrangeas Hydrangea seemannii and Hydrangea serratifolia offer an all-year-round interest, but they need to be grown in a warm, sheltered position to thrive. Though they are vigorous plants, to start with, they can be little slow. Climbing hydrangeas not fussy about soil conditions, but they may struggle on excessively wet or chalky soils.

Buying a hydrangea

In garden centres, climbing hydrangeas can be found in the ‘climbing plants’ section. They are usually sold in 2-3 litre pots. Mail order plants may be smaller. 
 

When to plant

Plant your climbing hydrangea soon after purchase. The best time to plant is in spring or autumn. Containerised plants can be planted all year round as long as the soil is not frozen, waterlogged, or excessively dry in summer.

Soil preparation

The soil at the base of a wall or fence (where climbing hydrangeas are normally planted) is in a rain shadow and so prone to drying out. To help establishment, improve the planting area (not just the planting hole) by digging in an organic soil improver, such as garden compost or a manure-based soil conditioner. Add a bucketful per square metre (yard).

Support

Though self-clinging, climbing hydrangeas usually need support such as wires or trellis to help them to get going. Tie in the new shoots until they form aerial roots that attach.  Mature plants are heavy so start from the beginning with a sturdy support.

How to plant

• Water the pot well before planting
• If planting against wall or fence, allow about a 45cm (18in) gap between the plant and the wall. Otherwise, a 20-30cm (8in-1ft) gap is sufficient 
• Make your planting hole as deep as the rootball and three times wider
• The surface of the compost in the pot should be level with the surrounding soil to avoid planting too deeply
• Firm in well
• Mulch with soil improver to reduce drying out of the soil, but leave a 10-15cm (4-6in) gap around base
• Water in, using at least the equivalent of a large watering can of water

Where to plant

Ideally, plant your climbing hydrangea against a north- or east-facing wall or fence.  A sunnier spot is fine, providing the soil doesn’t get too dry in summer. Evergreen Hydrangea seemannii and Hydrangea serratifolia need a sheltered spot as they are not fully hardy.

Though often slow growing to start with, they are vigorous climbers and one plant is sufficient to cover a house wall.

Watering

• Plants growing close to fences and walls tend to be in rain shadow receiving little rain, so keep an eye on their moisture levels and water in summer when dry
• Water newly planted climbing hydrangeas regularly during the first few of years when rain is lacking, from spring to summer, until fully established
• Reduce drying out of the soil by annual mulching with organic matter, such as leaf mould, garden compost or manure-based soil conditioner

Feeding

• Feed newly-planted climbing hydrangeas with general fertiliser such as Vitax Q4, Growmore or Fish, Blood and Bone after planting 
• Regular feeding of established plants is not generally need unless they are struggling. However, poor growth may also be caused by soil dryness rather than lack of nutrients and mulching and watering will be more helpful

Routine pruning

• Climbing hydrangeas produce flowers on last year’s shoots. To ensure that the plant have enough time to develop flowering wood for the next year, prune in summer straight after flowering 
• Prune back the flowered shoots and shortening any overlong new growth 
• Most flowers are formed towards the top of the plant, so try to leave as much of this un-pruned as possible or just lightly trim

Renovation pruning

• Hard pruning will reduce flowering for the next couple of summers
• Instead of severe reduction, consider renovation in stages over three or four years, reducing the size of the plant gradually
• Established plants will tolerate hard pruning in spring

They are easily propagated by layering.

Propagate from cuttings. Take softwood cuttings from late spring to mid-summer, semi-ripe cuttings in mid-summer and or hardwood cuttings in winter

Species hydrangeas can also be propagated from seed in spring.

• Young plants often taking three to five years to start flowering
• Excessive summer pruning or pruning later in the season as the flowers are formed on the last year’s growth

Frost damage

Last year’s shoot tips can be damaged by hard frost. In spring, lightly trim back any badly damaged shoots.

Hydrangea scale

Most noticeable in early summer when stems and leaves are covered with white, waxy, flat ‘blobs’.