A carnivorous plant is a plant that derives some, or most, of its nutritional needs from trapping and consuming animals (normally insects). These plants usually grow in soil which contains few nutrients (especially nitrogen), hence the need for capturing prey as an alternative means of obtaining what the soil lacks. Many carnivorous plants grow in acidic soils - the well-known Venus fly trap grows in the acid bogs of South Carolina, USA.

I have grown several varieties of Carnivorous plants in assorted small plastic and glass terrariums. For more information on setting up a terrarium for carnivorous plants, please refer to the 'How to... Set up a Terrarium' section from the menu on the left of this page.

Methods of Prey Capture

These fascinating plants have developed some truly innovative methods of capturing their prey. Some rely on wandering insects crawling in and getting trapped (such as the Pitcher plants), some have sticky leaves which flying insects get trapped on (such as the Sun Dews), and some have 'active' traps (such as the Venus fly trap) which actually close rapidly around their unsuspecting victim. There are many other methods employed by carnivorous plants, but the three techniques mentioned above are those used by the plants I have kept to date.

Once captured the prey is usually broken down by chemicals excreted by the plant. The nutrients dissolved in the resulting "soup" are then absorbed by the plant.

I have kept the following varieties of carnivorous plant:

Venus fly trap - Perhaps the best-known of the carnivorous plants, these fascinating plants capture small crawling insects in their many traps. The trap is triggered when the insect brushes against one of the fine 'trigger hairs' which each trap contains; causing the hinged trap to rapidly close around it's victim. The closed trap then seals itself and digestive enzymes are excreted to break down the insect.

Each trap functions independently, and can make about 12 trap cycles (closing, digesting, opening) during it's active lifetime. After this, the 'exhausted' traps usually seem to open fully and function photosynthetically.

Pitcher Plants - The above photo shows an aerial view of one of the pitcher plant varieties I keep. Water collects in the pitcher - any animals falling into the trap drown, and subsequently dissolve - and the plant absorbs the nutrients it requires. A sweet-smelling 'nectar' is secreted around the opening of the trap to entice insects to it, and the top of the trap is extremely slippery...

The inset photo shows a close-up of the top of a different variety of pitcher plant - you may be able to see the downward-pointing hairs which, along with the steep sides of the trap, make escape impossible for any insects which have fallen into the trap.

Sun Dews - This plant has long thin leaves, the sides of which are covered with fine 'hairs'. Each hair excretes a sticky liquid (which look like beads of dew, hence the common name). Flying and crawling insects making contact with these leaves quickly become firmly stuck to the leaves - which then wrap around the insect and dissolve it.

Feeding and Maintenance

In the wild these plants would be continually trapping and digesting insects, as they crawl or fly over the plants. Of course when these plants are kept indoors, some human intervention is required to ensure that regular food supplies reach the plants! During the warmer months of the year when the plants are growing actively, I aim to feed them every few days. All of the plants I have kept are largely green in colour, suggesting they are capable of photosynthesis as a means of supplying some of their needs.

I capture small spiders for the Venus fly traps, and ants for the pitcher plants. Venus fly traps expend a lot of energy in closing their traps, so it is vital for their continued well being that they get "something in return" for this energy expenditure. I use fine tweezers to gently place a spider into the traps, to ensure it can't get away and leave the trap empty! Once the 'trigger hairs' have been brushed by the spider, the trap closes with astonishing speed.

With the Pitcher plants and Sun Dews I normally place several ants in the terrarium and allow them to naturally wander into the traps/sticky leaves. They are usually rapidly enticed to the opening of the traps by the sweet-smelling 'nectar' which each plant produces.

The only 'maintenance' that is required is to water the plants regularly; ensuring the soil remains constantly moist. It is vital that you avoid using any form of fertiliser, and also tapwater - these plants will not tolerate the nutrients contained in these (regular feeding is all that is necessary to provide these plants with all their needs). Ideally you should use rainwater to water these plants, but if this is not available, boiled and filtered tapwater seems to work fine.

The only other requirement for the plants I keep is humidity, warmth and sunlight. A bright window sill can be perfectly adequate - providing high humidity is provided at all times (with the aid of condensation covers if necessary).