My cleverlittle carnivores
Watch out, insects – Monty Don has fallen in love with jaw-snapping venus fly-traps, and here he’s sharing his tips to help them thrive
DESPITE being a lateadopter when it came to carnivorous plants, I now enjoy them tremendously, although they are remarkably undemanding and, to be honest, unvarying in their performance. Not for them the eruption into flower or foliage in spring or any surprise fruiting in summer. They do put on new growth in spring and this summer have been much freer with their flowering than previously – which I put down to the extra heat – but by and large they do what they do almost all year round without fuss or bother.
Like many other people, I’ve been especially drawn to two kinds of carnivorous plant. One are the pitcher plants, or sarracenias, which entice flies and other insects into their tubular foliage and then quietly digest them at their ease. The other kind that have an excellent party-trick are the venus flytraps (Dionaea muscipula), whose spiny jaws close around any unfortunate insect foolish enough to land upon them.
I have two types of sarracenias – ‘Vogel’, which has plum veining set against luminous lime-green tubular leaves, and S. flava, which is less dramatically veined but still spectacular, especially when backlit with the light filtering through the tall, pitcher-like leaves. Sarracenias all come from the east coast of the US and Canada, as does the venus fly-trap, native to the sub-tropical wetlands of the Carolinas.
I also have a couple of sundews, Drosera capensis, another type of carnivorous plant that has spidery tendrils covered with sticky fine hairs that trap passing tasty insects. We have our own native sundew, Drosera rotundifolia, which, like all sundews, should not stand in bright sunlight but in light shade. D. capensis comes from South Africa and is less hardy, so over winter I’ll put it in the greenhouse – which is kept cool but above 5°C – and make sure it stays moist.
All these carnivorous plants have evolved to survive in almost nutrient-free conditions – typically acidic peat bogs – by getting all their nourishment from eating insects. This spring I divided most of mine by simply pulling them apart and repotting the separate pieces, and I found that a potting mix of half coarse sand or perlite and half fine pine bark compost works very well. The compost should not be rich in any way – it acts as a sponge as much as anything else, because the one essential is that the plants do not dry out, so they have to be placed into a saucer or tray that is kept permanently topped up.
Sarracenias have fairly specific needs. They must have bright sunlight and only the prostrate species (those that grow upon the ground or just above it) will thrive in shade. The plants can cope with heat as well as cold, but ideally the roots should remain cool and damp, which is why growing them in terracotta pots (which absorb more moisture than plastic ones) standing in rainwater that can be topped up daily works very well.
The venus fly-trap also prefers rainwater, and doesn’t require any extra feeding – even with insects! It grows best in a frost-free greenhouse or windowsill in direct sunlight.
In contrast, sarracenias are perfectly hardy and can be kept outside. Their leaves gradually die back in winter – cut them back to the base once they get tatty – and by January the top growth will disappear. They need a dormant cold period of at least six weeks, ideally between freezing and 12°C – a cold greenhouse, unheated room or porch is ideal. During this time they’ll need less water. Then in spring they’ll respond to warmer weather by starting to produce new leaves and grow rapidly.