The great indoors
In the first of a new series exploring the wonderful world of houseplants, glasshouse horticulturist Jess Snowball takes a look at Nepenthes a carnivorous plant in need of a little love and affection
In the first from our new columnist, glasshouse manager at the Chelsea Physic Garden Jess Snowball, considers the merits of growing houseplants. This month she looks at Nepenthes
What makes nepenthes such rewarding houseplants – aside from a satisfying decline in unwanted flies – is how responsive they are to love, care and affection. You can track their growth on an almost daily basis and watching your plant grow can become addictive as well as truly satisfying. In the wild nepenthes can grow in the ground as well as on rocks or on the surface of other plants; their climbing nature means they can grow in weird and wonderful ways in which it is possible to manipulate indoors. I adore them at height, so displaying them in hanging baskets gives the scrambling species the perfect opportunity to show off their natural habit.
A true carnivorous favourite, nepenthes, more commonly known as tropical pitcher plants, are notable for their beautifully decorative, almost alien-like leaf adaptation – the pitcher. Originating from tropical Asia, this dioecious group of plants, inhabits such harsh, low-nutrient environments that to survive they have had to undergo one of nature’s most bizarre transformation – turning leaves into an insect-catching pitcher. Basically, the leaf ’s midrib at the apex has extended into a tendril that expands to form a swollen pitcherlike container. The purpose of these colourful, pitchers is to trap and digest prey. The lip of the pitcher, known as the peristome, has slippery, downwardspointing hairs so any insects that land on this lip will slip into the pitcher and find themselves unable to climb out. Some species with larger pitchers, such as N. rajah, are able to trap small vertebrates, while species such as N. lowii and N. ephippiata, will digest the faeces of tree shrews.
I first encountered nepenthes as an intern at Chester Zoo, which holds the National Collection of around 170 species and many more natural and cultivated hybrids. I’ve since seen them growing in the wild on Mount Kinabalu in Sabah, Borneo, but they come from hugely diverse habitats, from Madagascar to Australia, meaning that a select few make excellent houseplants. I’ve grown a range of species, but N. alata x ventricosa (sometimes sold as N. x ventrata) is certainly the easiest and most straightforward to grow as a beginner. It is widely available and grows well in minimal humidity on a bright windowsill. My six-year-old female specimen of N. alata x ventricosa is quite the traveller, having lived in three cities and five houses. She has thrived on south-, east- and west-facing windows, and last year rewarded me with more than 30 impressive pitchers. Other easy-to-grow species are N. sanguinea, which has darker pitchers, and N. ventricosa, which has reddish pink or pale-green pitchers, both of which are also adaptable to lower humidity environments. If you want to place your nepenthes in the high humidity of a terrarium, then you might want to consider N. x hookeriana or N. ‘Bloody Mary’, one of the bushy cultivars, as both thrive in high humidity environments.
Cultivation
When deciding where to position your nepenthes it’s worth remembering that most species grow in the upper canopy of rainforests in partial sunlight, so a windowsill is ideal. Those rainforests are also warm and nepenthes will thrive best if kept at a temperature of between 15ºC and 25°C.
Nepenthes’ root systems are dark in colour, fragile and fibrous. They love an open, well-aerated, free-draining growing medium in which lots of moisture can be retained without being waterlogged. I find a 50:50 mix of sphagnum moss and perlite works well provided it stays moist. Many species are sold in peat, another medium in which they’ll also thrive, and when this is the case I soak the root ball to tease some roots out gently from the peat, before repotting in a sphagnum moss and perlite mix. Overwatering without drainage can cause root rot but as a rule plants should never be left to dry out. Nepenthes are known to tolerate hard water, but, if you use only tap water to water them then over time impurities will build up so use rainwater in the long term to prevent a shift in unhealthy pH levels. You can apply a low rate of a balanced liquid feed throughout spring and summer, but there is no need to feed in the winter months, as growth will naturally slow in winter. WHERE TO BUY – MAIL-ORDER SUPPLIERS Hampshire Carnivorous Plants Tel 023 8047 3314, hantsflytrap.com (by appointment only). Wack’s Wicked Plants Tel 07530 176624, wackswickedplants.co.uk (by appointment only). Jess Snowball is glasshouse manager at the Chelsea Physic Garden, London.