Inspired by the Botanic Garden: Growing tropical plants at home

I have always had a love of plants and gardens, but despite developing a familiarity with common garden plants as a youngster nothing prepared me for my first encounters with tropical plants in the Palm House at Kew, and the Tropical Houses here at Cambridge University Botanic Garden. The plants were completely alien to me with enormous leaves and exotic blooms, all growing in a warm and humid environment. The combination of plants and tropical atmosphere created an intimate environment. I was mesmerised by the lush foliage of plants such as the Asian taro (Colocasia esculenta), the Colombian black-gold philodendron (Philodendron melanochrysum) and cocoa (Theobroma cacao). Seeing such diverse, lush vegetation was mind blowing.

Originating from equatorial tropical rainforests of South America, Central America, Central Africa and south-east Asia, tropical plants have evolved to survive, and even thrive, in hot, humid conditions. Tropical rainforests are made up of distinct plant layers, with the highest one formed of slender-stemmed emergent trees which can reach 60m in height and tower above the rainforest. Beneath these sits a dense canopy of shorter trees to 40m high, and these create a rich habitat for wildlife, including insects, reptile, birds and mammals, but also block out light to cast dense shade across the rainforest floor. An understorey of emerging saplings grows in cooler, shady conditions, and here seedlings may grow to plug the canopy where gaps appear. The lowest layer is dark, and is formed from decaying roots and rotting plant matter which form a moisture retentive, humus-rich forest floor. Together these make a complex habitat containing an array of highly adapted plants.

Tropical plants have evolved to suit shady, hot, humid conditions, in which annual rainfall is high, and temperatures remain constant, usually between 26ºC and 29ºC. Plants show a range of adaptations to these conditions. The tallest, emergent trees have buttress roots to help stabilise them, and tree trunks have smooth bark which helps water flow freely to the roots. Waxy leaf surfaces and drip tips at the end of the leaf help channel water from the leaf surface to prevent diseases. Woody vines (lianas) clamber up through trees in search of light and produce leaves and flowers in the rainforest canopy. Epiphytic plants are those which grow on host plants without taking nutrients from them. They gather moisture and nutrients from the air, rain and debris high in the forest canopy.

Our tropical houses grow a host of plants to inspire and create a sense of wonder, though unfortunately many of these are not widely available. Perhaps the plant that most captivates visitors is the jade vine (Strongylodon macrobotrys), an endangered bat-pollinated liana from the rainforests of the Philippines, which can reach 20m in height and produces pendent flower clusters along a central stem (racemes) of brilliant, turquoise, claw-like flowers – a real showstopper.

But other plants are equally beguiling. The titan arum (Amorphophallus titanium) is native to the rainforests of Sumatra. Unfortunately for us it is shy to bloom, but the flower has a ruffle-like collar and an erect thick spike of tiny flowers (spadix) – up to 3m tall, and emits a foul aroma to attract pollinating beetles. Perhaps not a horticultural beauty in everyone’s eyes, but certainly a botanical curiosity.

The calabash nutmeg (Monodora myristica) is an impressive tree bearing speckled, lantern-like flowers in the canopy of our tropical houses. Carludovica palmata (Panama hat palm) produces large, pleated fan-like leaves and is used to produce Panama hats. Members of the ginger family are quite at home in the tropical conditions here, and include the beehive ginger (Zingiber spectabile) and the torch ginger (Ettlingeria elatior). Several Dutchman’s pipes scramble through hosts such as the Darth Vader plant (Aristolochia salvadorensis) and Aristolochia arborea. Epiphytic plants can also be found here. Orchids in a range of sizes and colours from rainforests across the globe nestle amongst the limbs and foliage of host plants, and Spanish moss (Tillandsia usneoides) from the Americas hangs curtain-like from tree branches.

These are just a few of my favourites to whet the appetite, but there is always something to capture the imagination in these verdant houses.

The chances are that if you grow house plants you may already be growing a tropical plant. Asian moth orchids (Phalaenopsis species) are readily available and adorn many kitchen windowsill, often with little horticultural attention, though a plethora of other tropical orchids are available.

Popular tropical house plants include the herringbone plant (Maranta leuconeura), the money tree (Pachira aquatica) and the fiddle leaf fig (Ficus lyrata). While we are fortunate at the Botanic Garden to be able to dedicate space solely to the cultivation of tropical plants most of us don’t have that luxury in our homes. There is still scope to grow elephant’s ears (Alocasia species and cultivars), parlour palm (Chamaedorea elegans) and many other tropical plants if you provide the right conditions. All will thrive in indirect light, a minimum temperature of 15ºC, a humid environment provided through regular misting, well-drained compost, and watering when the compost surface dries out.

Many will also relish spending a summer in your garden, providing that they aren’t in bright sunlight which may scorch them. If you’re encouraged to start growing tropical plants at home now is a good time to dip your feet with garden centres and on-line retailers offering a host of plants to choose from. What better way to create a horticultural talking point in your home or garden than adding a touch of the exotic such as a banana (Musa basjoo) or stag’s horn fern (Platycerium bifurcatum) to your plant collection. And of course, many of these will grow outdoors in pots or in the garden over summer, but will require either the protection of a greenhouse or conservatory in winter, or wrapping with fleece or hessian over winter if left outside.

If you fancy bringing a touch of the exotic to your own patch there are many plants you can try at home. Some of the hardier bananas, such as Musa basjoo, are good candidates. These coupled with plants such as pineapple lilies (Eucomis pole-evansii), and arum lily (Zantedeschia aethiopica) in a warm, sunny corner will bring a hint of warm, tropical climes to your summer garden. But if you’re really not inclined to test out your green fingers, and a trip to the tropics is off the radar, a visit to the tropical houses at the Botanic Garden will provide a taste of the tropics.

• Take a moment to relax and enjoy your garden.
• Harvest crops such as lettuce, carrots, beetroot, beans, sweetcorn and onions.
• Continue deadheading flowers in your borders and pots to encourage more flowers.
• Take softwood cuttings of plants such as lavender, pelargoniums and penstemons.
• Pinch the growing tips out of tomato plants in the garden to encourage fruit to develop and ripen.
• Keep pots well-watered.