What does “exotic” actually mean? Plants that come from far away? Plants that look weird? Crazy lush growth and greenery like a jungle? As a concept, “exotic” can mean many things. For the purpose of this article, we’ll go for the idea of a warm, wet, tropical atmosphere. Success in the project of creating an exotic garden, over anything else, rests on which plants you choose that are both hardy and growing with lush abundance: leaves, flowers, vining and palm-like silhouettes.
1 – Go for more and more lush growth
Find the right spot
You might not believe it, but a south-facing strip of sunny land isn’t necessarily the best spot to reproduce a tropical ambience. Many exotic plants are used to growing in the moist underbrush of tropical rainforests. In South-East Asian and Southern China (Yunnan and Sichuan), many plants exist that look very exotic, but yet still cope well with winter temperatures like those we have in our temperate climates. The main difference is summer: over there, it tends to rain a lot thanks to the monsoon.
This will serve to guide us: our goal will be to maintain high moisture levels in the air during summer.
This situation is often easier to command along the coast, near a pond, or on north or east-facing plots. Possibilities also include man-made earthworks, such as digging out a basin or drawing up an artificial brook. Secondary parameters include: rich soil, not chalky; shelter from wind and harsh cold air.
Shape the land
You don’t need a vast expanse to simulate lush, abundant growth. The trick is to create a walkway, twisting and turning around living green obstacles, skimming around a pond or stream, be it running water or not.
- You’ll increase the “rainforest” appearance by planting tall plants. When digging out the bed of your stream, bring the soil up to the sides to create mounds to both sides of the waterway.
- With a thin, tar-covered polypropylene liner (a quarter-inch or 5 mm thick), you can waterproof the stream and ensure it won’t erode. Thanks to the tar, a simple blowtorch is enough to weld portions of the tarpaulin together. Remove all rocks, especially the sharp ones, and spread a smooth layer of sand before spreading the tarp. When you’re finished, cover the liner with at least 10 inches of soil (25 cm), in the bed and along the banks.
Ready the area beforehand: surround it with local protectors
For this project of creating that specific, moist micro-climate that exotic plants need, you’ll have to add a few perfectly hardy plants that are well suited to the soil type and local climate.
- Create a hedge with such evergreen plants to the North and East: they will protect that small pocket of growth from the cold. Also plant them to the West so that strong winds are cut off. Of course, depending on your climate and local setting, you’ll probably have to adjust these guidelines somewhat (neighboring buildings, slope…).
- Plant a few beautiful shrubs that grow fast. These will increase biodiversity, add spots of shade and of part sun, create dryer spots and cooler ones.
2 – Choosing your “exotic” plants
After 2 or 3 years, that little cocoon is ready to welcome its first “fragile” plants:
- Some of them you’ll keep in pots so you can bring them indoors for winter,
- while others will benefit from a light winterizing fleece so they can stay put outside,
- but most will make do just fine with a 4 to 8 inch (10 to 20 cm) layer of leaf mulch to fend off the harsh cold air.
Mulch is critical in this type of garden because it increases soil moisture and nourishes it with humus as it breaks down. Species that you can consider usually grow in tropical areas, but in high altitude, up to about 4,000 feet (1500m). Remember that less intense cold, say 14°F (-10°C), for an extended time period, can often be more detrimental than a sharper cold spell like 5°F (-15°C) which only lasts a short while.
Composite and lobular leaves
Leaves that are actually fronds with many tiny leaflets, like the Aralia elata shown here, have a magical effect: they let light trickle through, twinkling as the wind makes them flutter. This visual effect promotes the feeling of rich, lush vegetation. You’ll get this with:
- all the palm trees: Trachycarpus fortunei which resists 0°F (-18°C) for a short while and does fine under snow!
- and also with staghorn sumac (Rhus typhina) which is also extremely hardy.
- Bamboo, for their part, not only play with light, but with sound, too: they creak and clunk as the wind shoves them around. Select them carefully because some species really turn invasive. Best are compact, non-running varieties such as Fargesia murialae which has a dense clump that won’t exceed 10 to 15 feet (3 to 5 meters) tall and 6 feet wide (1.5 m). Invasive bamboo like Phyllostachys are generally much less invasive in cool, rich and clayish soil than they are in sandy soil. Also, you have the option so set up a rhizome barrier, just in case.
- Giant perennials such as Aralia elata and Dahlia imperialis will send up fronds to over 10 feet / 3 meters high.
The epitome of tropical lush growth is clearly the banana tree, with its large, shiny leaves. The hardiest among them is Musa basjoo ‘Sakhalin’ which simply needs a good layer of mulch to survive our winters. Extra protection will let you keep a stem alive from one year to the next. Musa sikkimensis ‘Red Tiger’ is also quite hardy and boasts red markings.
- >> Dig deeper: How to grow banana trees
A more classic option that’s perfectly hardy is Paulownia tomentosa, easily kept from growing tall by cutting back to the stump every year. It bears very large leaves that are very effective at blocking out a fence or structure the shrub with arching, chandelier-like branches.
- To get this result, at the end of winter, cut the clump back to the stump or to 20 inches (50 cm), depending on what you want it to look like.
- In spring, only keep 1 to 3 stems so that all the plant’s efforts go to growing more leaves.
Extraordinary leaves and flowers
Play around with rare leaf shapes and colors, like a canna species that will have red-lined leaves, or the unexpected gigantism of a clump of Hibiscus moscheutos. Here, a ‘Sum and Substance’ Hosta which has particularly large leaves.
Exotic, out-of-the-ordinary bloomers should be preferred, like the fruit-flower of the pineapple plant Eucomis bicolor and Hedychium that has orchid-like flowers.
Below: bright light brought on by a Hedychium ‘Tara’. However, feel free to fill in void spaces with reliable local species, too, like flower-bearing solidage (Solidago), Rudbeckia, persicaria and ligularia.