Posted on | September 1, 2012 | 3 Comments
What a difference a year makes – this time last year all the Parthenocissus quinquefolia -Virginia creeper which covers much of my house here at the Exotic Garden along with a very rampant Vitis coignetiae -Crimson Glory Vine, were going red, whereas this year there is hardly a sign of their fabulous coloration, so thankfully they aren’t going to put on their fiery autumnal show just yet!
Some plants flower more profusely when the days start to cool down and one that I have often mentioned over the years and am doing so again now, as they are so stunningly beautiful are the many Thunbergia’s. They are fast growing climbing plants, usually considered as annuals here in the UK as they don’t like cold temperatures. In a warm climates were the night temps remain above 15C, they stay evergreen and bloom for at least three seasons of the year. The most readily available forms here in the UK are the ‘Susie’ range, which can be obtained from most seed companies in late winter for early spring sowing.
In recent years though, I have concentrated on growing them as returning perennials that can easily be overwintered in frost-free conditions – if you have the room of course! These ones are generally grown from cuttings and bought as plugs or small plants in the spring, though many of the larger garden centres and DIY stores are selling them this year as fully flowering plants often already 2ft or more tall, though by this time of year they are usually 4-8ft tall if grown up canes for support. They tend to be rather expensive as an annual so I would definitely recommend trying to over-winter them if you have the inclination and room to do so. I wait until they have been lightly frosted, then cut all the top growth off, then store the containers almost dry until the spring returns.
The genus Thunbergia is in the Acanthaceae family and are native to tropical regions in Africa, Madagascar and Southern Asia, though they are now spread throughout the tropics with some exceptionally beautiful forms like Thunbergia grandiflora and Thunbergia mysorensis that can become enormous with time, especially T. grandiflora which can easily cover a large tree! Unfortunately, the large forms need tropical heat to grow well! The common name for this family is Clockvine, though the commonest forms available here in the UK as seeds are known as ‘Black-eyed Susan’. The generic name Thunbergia honours Carl Peter Thunberg, a Swedish naturalist and student of the venerable Carl Linnaeus.
My oldest plant is Thunbergia gregorii; the ‘Orange Clockvine’ and is about eight years old, flowering profusely every year. The amount of colour that can be put out by this Thunbergia is unsurpassed, as it glows in the evening with intense beacon-like pure orange. It is a woody perennial that will creep and crawl over everything in reach and provided it is kept frost free during the winter months, will give years of pleasure. In the last few years I have seen it for sale under the name Thunbergia ‘Mellon’, if you see one ‘grab it’ as they don’t seem to be generally available, which is a shame as it is such a stunning plant for the summer garden and a real eye catcher!
I have also tried two fairly resent introductions, both with large 1½ins wide flowers produced in abundance all summer long. Thunbergia ‘Lemon’, as its name suggests, has the brightest lemon yellow flowers with a jet black eye in the centre. Thunbergia ‘Red and Orange’ has rich, almost burnt orange flowers with a dark reddish-brown eye, very attractive. Thunbergia ‘Charles Star’ is a new introduction with large yellowy-orange flowers, while ‘Thunbergia ‘Arizona Dark Red’, as its name suggests has intense orange almost red blooms. There is even a pure white form simply called Thunbergia ‘White’. This week I discovered yet another new one at a local garden centre called Thunbergia ‘Raspberry Smoothie’ which has large pale lilac-pink flowers and slightly hairy greyish green foliage – a very exciting new one to add to the collection!
Another two I have tried for the first time this year are Thunbergia aurantiaca ‘Gold Eyed Susan’, which has a smaller orange flower about 1ins across, with a pale green eye, while Thunbergia alata ‘Sunrise White’, as its name suggests, is white with a black eye. There is also a pure white form called Thunbergia fragrans which is easily grown from seed, though they can be hard to find. If you are ‘au fait’ with the internet, nothing is impossible to find with a little effort!
Another plant that is always popular here at the Exotic Garden and also in the Acanthaceae though it looks nothing like a Thunbergia or an Acanthus come to that – is Strobilanthes dyerianus, more commonly known as ‘Persian Shield’. It is native to tropical Asia, specifically to Myanmar formerly known as Burma. What a stunning plant it is, in fact some visitors think it is made of plastic! It is a very bold-looking sub-shrub with iridescent purple leaves with prominent dark green veining developing a silvery sheen with age. This rather alluring plant is good either as summer bedding or grown in a container. It prefers dappled shade to bring out the best coloration as full sun can bleach the foliage.
During the winter months it becomes semi-dormant, dropping most of its leaves – this is when most of its pale lilac and rather insignificant flowers appear. When in flower the remaining leaves become very small compared to the lush summer growth and that is when people tend to throw their plants out, as the plants tend to look rather feeble! Endure its straggly winter appearance and it will reward you in the spring and summer with masses of new growth – a two to three year old plant as mine are now, is an impressive site to behold.
Its spectacular leaves combine well with the silvery velvet foliage of Plectranthus argentatus and grows to about the same size as ‘Persian Shield’. It is a spreading evergreen sub-shrub in the mint family hailing from New South Wales in Australia where it can be found growing on rocky outcrops. It has hairy stems and leaves which are silvery grey and soft to the touch. In high summer short racemes of small bluish-white flowers with purple bracts are formed, looking very attractive above the silvery foliage.
There are so many plants and plant combinations in the garden that look absolutely magnificent at this time of year and lots more to come, the summer is by no means over yet! This is the time of year to savour our gardens in the early September sun…