Climbing Hydrangea - Hydrangea anomala subsp. petiolaris

Climbing Hydrangea is in my opinion one of the most attractive climbing plants. Although to date rarely cultivated in Poland, it makes a spectacular display, for instance in SGGW (Warsaw Agriculture University) Arboretum in Rogów, climbing up the trunks of the old pines.

Jacek Borowski

 
Climbing Hydrangea (Hydrangea anomala subsp. petiolaris) is native to Far East (Japan, Kurile, Sakhalin, Korea), and such origin ensures its full hardiness in our climate. It climbs by means of adventitious roots that twine round the support.

Hydrangea petiolaris climbing on the tree (ph. Sz. Marczyński)

It attaches itself tight to rough surfaces, and though it's rather a slow grower, after a dozen years or so, it may attain a height of over 10 m. It's almost as shade tolerant as ivy, and thrives best in semi shaded positions in fresh, humus, acidic soil, but it will also grow well in alkaline soil. One thing Hydrangea doesn't tolerate at all is drought (especially during the first few years after planting). It appears at its most attractive when in bloom, usually in late June, early July. After fading, its partially dried flowers stay on the bush until winter.

Lacecap-style flowers are 15-25 cm wide and can cover the plant almost completely, as if with a veil. Greenish-white small blooms, nectar suppliers to the to bees, are encircled with larger (about 2 cm in diameter), sterile flowers. The fruit is rather inconspicuous but it provides a food source for many birds and will attract them to our garden. Its heavily branched and slightly twisted stems, covered with red-brown or tin-brown bark, provide a striking silhouette in the winter garden. Leaves on long petioles appear early in spring. In autumn they turn yellow and usually stay long on the stems.

flowers Schizophragma hydrangeoides (ph. J. Borowski)

When you plant it next to a wall it's better to lay the stems along the ground or tie them up to supports in order to strengthen the brittle stems before the plant starts to attach itself to a support using adventitious roots. The plant is slow to get going and it makes little new growth in the first two, three years, focusing more on creating the root system.

Once it's well established it will start growing vigorously even up to 1 m in a year. It may start flowering in the 5^th - 6^th year after planting. Climbing Hydrangea will not climb well on the fresh, calcareous-concrete plaster. Only after a few years, when the base has stopped burning the adventitious roots, will the plant start its normal growth.

Trees are the most common support for hydrangea, but it also looks very attractive scrambling over the walls. It's suitable for covering arbors or pergolas of a solid construction. It may also grow without any support at all, as a picturesque ground cover plant, growing even up to 1-2 m high. In nurseries it's usually propagated from seedlings, but in the garden it's best to propagate it by layers.

Schizophragma hydrangeoides groing around the tree (ph. J. Borowski)

There exists another kind of Hydrangea, Japanese Hydrangea - Schizophragma hydrangeoides that resembles Climbing Hydrangea, but is even less frequent. It has almost identical habitat requirements. It thrives best in slightly acid, fresh soil in semi shade.

It climbs using adventitious roots. It's a slower grower than climbing hydrangea. Its lacecap-style flowers appear two weeks later and they are encircled by a garland of snow-white sepals. Heart-shaped, deep-green leaves turn yellow in autumn. It's ideal for training up walls, pergolas or as ground cover. Its silvery-leafed variety Schizophragma hydrangeoides 'Moonlight' is very attractive, but it may freeze during severe winters.