With the arrival of high summer gardeners can, at last, be gluttons. The abundance of plants means that almost every colour, fragrance, shape and form is there at the feast. But, in the borders, the tall flowering plants are missing: the Delphiniums and Verbascums are over; the Actaea and other lofty late perennials are yet to come. So, summer-flowering climbers, covering obelisks, cane-wigwams or permanent structures, are indispensable for bringing height to the summer border, while screens of fast-growing climbers can change the shape of the garden or mask fences and sheds.
The growth rate of many climbers during the summer is phenomenal. Sow Morning Glory in April and in four months it will have grown 5 metres. Ipomoea ‘Heavenly Blue’ may be commonplace, but I still thrill to its sky-blue trumpets and grow it most years, usually entwined with the deep purple and dark blue flowers of Sweet Pea ‘Matucana’. In Catalonia you see Morning Glory grown in window boxes and trained on wires to frame the window. It is a striking sight, but probably relies on the crystal light of the Mediterranean to be most effective.
Many tender perennial climbers can be grown as annuals, or over-wintered in a green house and bedded out in late spring. Lophospermum erubescens is a vigorous plant that will grow 10 feet in a season. Known colloquially as the Creeping Gloxinia, its deep pink flowers more closely resemble a foxglove. The heartshaped leaves have a soft, velvety texture and make a very dense covering, so it is best grown on its own. The Chilean Jasmine, Mandevilla laxa, has similar flowers but more flimsy, twining stems. I’ve seen it threading around wrought-iron railings in a London garden, where it survives the mild metropolitan winter, but in most parts of the country it will need protection. It is an altogether more delicate and taller plant than Lophospermum but runs out of steam more quickly: Lophospermum will be flowering for weeks after the last of the Mandevilla’s flowers. Rather than sow it each year, I cut down my Lophospermum in October when they have finished flowering, pot them up and keep them in the greenhouse during the winter. Treating tender climbers in this way gives them a head start the following spring and produces bigger, more floriferous plants.
Rhodochiton atrosanguineus is a far less boisterous plant that will clamber, using its twining leaves for support, through other plants and up fences throughout the summer. It has dainty deep magenta bells that develop improbably long purple tubes from the centre. To grow it as an annual you need to start the seed in a heated propagator in January or February. Equally slow-growing is Tweedia caerulea, whose cerulean stars are a match for Morning Glory. In its first year it barely reaches a foot tall, hardly a climber at all. If you can give it a frost-free home during the winter it puts on a spurt the following year and will climb to three feet.
If you have been seduced by the vogue of making exotic gardens with echoes of the jungle, then tropical climbers will add to the effect. Bomarea caldasii, with bunches of bright orange tubes, will need some winter molly-coddling to survive. A hardier plant from the tropics is Eccremocarpus scaber. The flowers are typically scarlet, but there are many cultivars in a range of colours through orange, pink and magenta.
Most climbers revel in open, sunny conditions but Trachelospermum jaminoides will grow well in a sheltered, shady site. Once the plant is established it becomes covered with an abundance of scented, white flowers. Only plant it if you have lots of space because it can grow to twenty feet. At a more modest four feet, Codonopsis convolulacea is also at home in shade. The genus has several other species, scandent rather than climbing, usually with similar mauve bell-flowers.
Some climbers are edible as well as attractive, and many beans, gourds and squashes are far too beautiful to be hidden away in the vegetable plot. Most runner beans have scarlet flowers but there are variations: ‘Sunset’ is pale pink; ‘Painted Lady’ red with a white lip; while her sister, ‘White Lady’, has pure white flowers that open from yellow buds. If you are growing them for decorating the garden rather than for the table, pick the beans as soon as they form. Once the plant is producing beans it will stop producing flowers. The most spectacular of the legumes is the purple-leaved Lablab purpureus ‘Ruby Moon’. The dark foliage will last well into the autumn, providing a stunning background for its magenta-pink flowers. The purple seed pods are small and flat, so they don’t weigh down the support like runner beans do.
A strong supporting structure is essential for climbing gourds. I grow them for their dramatic fruits, rather than their (often insipid) flowers . British seed companies have finally got around to offering lots of gourds and squashes on their lists, but I tend to avoid the purely ornamental varieties: there seems no point to them when squashes are so delicious and the edible ones are just as decorative. With just a few of these climbers in the garden, summer’s banquet is complete.