The secrets of the wisteria pergolas in the Private Gardens at Petworth House

The wisteria at Petworth's private garden is simply astonishing. Non Morris takes a look at how it's done, with pictures by Val Corbett.

The beautiful pergolas in the Cloister Garden are trained with Wisteria floribunda Alba, a white Japanese wisteria selected for the tantalising length of its racemes — up to 24in — and the way the flowers open gradually along the stem, which prolongs its flowering period. The wisteria is pruned once only, in September.

The Private Gardens at Petworth House, West Sussex. ©Val Corbett / Country Life

Elegant square arches are clothed with Trachelospermum asiaticum. ‘It’s a good green, recovers quickly from clipping and flowers much better than Trachelospermum jasminoides,’ says Lady Caroline Egremont.

‘In the beginning, I wound it round the metal posts, weaving shoots in as we went. Now, it is only sheared after flowering.’

The Private Gardens at Petworth House, West Sussex. ©Val Corbett / Country Life

The wisteria is underplanted in greens and whites, including white chionodoxa and hellebores for spring, towering Eremurus Joanna and Digitalis purpurea Camelot Cream for summer and Aster divaricatus and white nerines for autumn.

The Private Gardens at Petworth House, West Sussex. ©Val Corbett / Country Life

Key plants for May when the wisteria is in flower are Camassia leichtlinii Alba, the spires of long-lasting creamy flowers providing a delicate starry echo of the wisteria, and Euphorbia polychroma, whose mounds of bright yellow-green light up this lower layer. The ferns Polystichum setiferum Pulcherrimum Bevis and Polystichum munitum lend upright structure and a darker-green backdrop to the camassia and to the delicate creams and whites to come.