Get that tropical garden feel with some trompe l'oeil planting

Although in the midst of the Dog Days of August you could be forgiven for thinking otherwise, mainland France has no actual tropical regions – the DOM-TOMs (overseas departments and territories) are another matter. Despite the sultry days of yet another canicule (heatwave) or the astounding power of monsoon-like summer storms, the climate is not suited to jungle plants.

However, in the garden you could employ a technique long practised in France, especially in the 18th Century in interior decoration, of trompe l’oeil (literally tricking the eye). Complex architectural forms like recessed niches, vaulted ceilings, columns, marble, stone and tiles, even views and vistas, were rendered in paint on plain walls. The eye was fooled into seeing what the skilled use of perspective, colour and line wanted. You can use this device to undertake “jungle” planting schemes, creating a tropical trompe l’oeil effect.

Organic matter counts

The area you choose for your jungle should be quite sheltered, not exposed and dry. A corner near a wall is good, or by a tall hedge. If it has a water feature – a small pond or a spout with water dripping onto a hidden reservoir, circulating using a solar pump – so much the better. Dig in as much organic matter as you can – you want lush growth. You need to create the illusion of a wall of green. If you are allowed to water, give everything a good drench with a fine mist spray early in the morning.

Choose plants with big leaves in a variety of forms. Cannas and bananas (Musa basjoo) will give you height and colour, with a very tropical look. They can cope with some frost if left in the ground over winter, especially if you put a thick mulch over the tubers and crowns. If you live in a region with very low winter temperatures or your soil is waterlogged, lift and pot your plants before storing them in a cool barn or garage. Replant the following spring – bananas are herbaceous perennials and die back over winter anyway.

You can grow ginger from the fat rhizomes sold in the produce section of the supermarket – simply place the ginger on damp gritty compost and it will soon start to shoot. Bring it indoors over winter. Fatsia japonica, the false castor oil plant, was tough enough to survive in my previous Yorkshire garden. Its glossy wide leaves layer one upon the other to give fullness. Ricinus communis, the castor oil plant, has a similar growth habit and can be grown easily from seed as an annual. It has exotic, spiky-looking red flowers and red stems. It is poisonous, so be aware.

Tetrapanax papyrifer ‘Rex’, the rice paper plant, is bigger still. Let it grow tall but cut it back hard every two or three years to increase the leaf size. Use the same cutting-back technique on Paulownia tomentosa, the foxglove tree, to produce the largest, almost heart-shaped leaves. It is a pity, though, as you will not see the flowers that give it its common name except every other year.

Other trees to consider for your tropical garden are figs with their soft, spreading leaves, a palm (Chusan palms are very hardy), or the dark-textured leaves of a loquat known in France as a néflier du Japon (Japanese medlar).

Oversized flowers will add to the tropical feel and none are bigger than the marsh hibiscus – in France they are called hibiscus des marais. Sold as potted plants in many markets in the summer, they do make good garden plants. The flowers are at least tea-plate size and sometimes larger and come in all shades of red and pink, white and yellow. They will die back to dry sticks above ground in the autumn after the foliage has turned colour and dropped. I leave the stalks to show me where the roots are the following spring. After a few years, dig up the roots, divide and replant. Hibiscus coccineus,  is a smaller flower in a very vivid red with very dissected leaves – it will grow to 2m.

When considering your planting, think about layers. You should include lots of ground cover – heucheras can add low-growing leaf colour, as can begonias. Surprisingly, there are semi-frost-hardy begonias that self-seed freely in my garden in the southwest, coming back year after year, even surviving temperatures of -10°C. If you are uncertain about how they would fare in your garden, use bergenias instead – their common name, January plant, gives you a hint about how robust they are. A large-flowered, dark-leaved periwinkle can scramble around the base of larger plants. Acanthus can be planted under taller shrubs: its arching, large-toothed leaves give way to spikes of white and mauve flowers.

In tropical gardens, perfume is very important. You want something opulent like jasmine or Trachelospermum jasminoides, not sharp and light like lavender. Brugmansia, Angel’s Trumpets, can often be found in discount supermarkets in April. They may look a bit weedy, but put them in decent-sized pots with some good compost and they will romp away. The leaves are large, but the flowers are huge and exude a heady perfume after dusk. The “Scentsation” nemesias will give you wafts of coconut, heliotropes smell like sweet cherry pie, and you can have a chocolate-scented cosmos or a chocolate vine (Akebia).

Twining vines will add to your jungly atmosphere – annuals like Morning Glory, Spanish Flag or Black-Eyed Susan can wind their way up other plants or up moss stakes sold for house plants. Campsis, the trumpet vine, can be a nuisance in some places with its rampant growth, but in this situation it will look entirely at home. 

Add some ferns in the shadiest corners – some need a lot of moist air, others will grow in drier spots.

Enjoy your tropical trompe l’oeil – it will be like a holiday without leaving home.