Posted on | July 12, 2008 | No Comments
What fickle weather we’re having. At least the nights are warm enough for our garden plants to really get moving. It’s a joy at this time of year to see plants coming into flower after such a cool spring.
One of my favourites at this time of year are members the Thunbergia family with their radiant, almost day-glow colours. One beauty I have been growing from seed since a child is Thunbergia alata or Black-eyed Susan.
This fast-growing climber is a native of east Africa which, as might be expected, enjoys warm, slightly humid weather with shelter from cold winds. It used to be regarded as a conservatory climber for growing in tubs, soil borders or from hanging baskets, but in recent years has become a popular subject for outdoor cultivation, both in baskets, pots and in more protected corners of the garden.
The most commonly available forms from seed are the ‘Suzie Hybrids’, in shades of orange or white. Seed sown from March to May will flower almost continuously from June to September, provided that the flowers are deadheaded regularly. Later in the season, it is advisable to let a few go to seed, so you can grow them again the following year.
Thunbergia alata ‘Superstar Orange’ is a stunning bright orange Black-Eyed Susan with larger flowers than normal in a shade of intense orange. An absolute stunner, it’s a vigorous plant, quickly covering a trellis against a sunny fence, or growing up an obelisk in a container.
In recent years Thompson and Morgan have produced a stunning new Thunbergia alata named ‘Blushing Susie’ – the result of years of careful selection by T&M’s flower breeders. Unlike many other varieties that only have an odd red bloom, with a high proportion of salmon, ‘Blushing Susie’ is predominantly red, with other shades of ivory and apricot adding contrast. All in all, it makes this a very exiting climber to have in the garden. It looks spectacular when used tumbling over containers, twisting around basket chains or climbing obelisks in the garden or containers to 90-150cm (36-60in).
There are several perennial Thunbergias worth trying in a warm spot in the garden or conservatory if your garden is exposed. One of my favourites is the Orange Clock-Vine Thunbergia gregorii. The amount of colour that can be put out by this variety is unsurpassed, as it glows in the evening with intense orange. This gem is a continuous grower and will creep and crawl over everything in reach in ideal conditions.
In fact, it can be seen doing just that at Blandy’s garden in Madeira where the winters are mild. In our gardens though, it will die to the ground in winter and should return in the spring provided that it is well-mulched and planted in a sunny, protected spot.
Thunbergia battiscombei is another perennial worth seeking out. It is a herbaceous, weakly stemmed perennial vine that tends to lean upon other plants for support. When unsupported it will form a symmetrical mound of flopped over stems to about 3ft (1m). The light green stems hold large 5-7in (12.7-17.8cm) heart-shaped leaves. These are bright green, smooth-edged and arranged oppositely along the stems. From the axils (where the leaf attaches to the stem) rise racemes (clusters) of attractive 1in (2.5cm) long hairy white flower buds. From these emerge the intense blue-purple trumpet-shaped flowers that create such a stunning sight against the handsome foliage.
For sheer grandeur and opulence, nothing can beat Thunbergia grandiflora from India. From a distance, this creeper creates a wall of flowers. Each individual flower is about 3in (7.6 cm) long and they are borne in drooping clusters on stems often many feet long. The most commonly seen varieties are sky blue to light violet, although there is a white-flowered type as well. The leaves are leathery and have a distinctive elongated heart shape.
The plant grows fast in warm weather, easily covering a trellis or large section of fence in one season in a hot summer, though with our cool summers this beauty is best grown in a greenhouse or conservatory where the roots can be kept above 7C (45F) during the winter. Under frost-free conditions Thunbergia grandiflora stays evergreen. In the tropics this amazing vine can cover a whole tree tens of metres high.
My personal favourite has to be the Clock Vine Thunbergia mysorensis, another fast grower in warm conditions that’s best suited to a conservatory here in Britain. This has to be one of the most beautiful climbers in the world! In the tropics and sub-tropics, this treasure flowers almost every day of the year, with a mature specimen bearing hundreds of 5cm (3ins) yellow and russet-red flowers in spectacularly long hanging chains 1-1.5m (3-4ft) long, which would look excellent hanging from greenhouse and conservatory rafters. The leaves are 12-16cm (5-6ins) long, in a shade of handsome dark glossy green. The whole plant has a more delicate appearance than T. grandiflora.
Whether you’d like to try some of the easily grown annual Thunbergias or – like me – are tempted to try some of the heat-loving tropical forms, you will certainly not be disappointed as they’re all exceedingly exotic plants.
The Exotic Garden is open every Sunday afternoon (1-5pm) until the end of October and at other times by appointment (tel 01603 623167). Entrance is £4.50, children free. For more information visit www.exoticgarden.com The entrance to the Exotic Garden is to the left of the Alan Boswell Insurance building at 126 Thorpe Road, Norwich NR1 1UL.