Carnivorous plants, or insectivorous, are a species of plants that have evolved in different ways to conventional plants. Carnivorous plants have adapted to grow in places where the soil is poor in nutrients which is why they feed on insects.
In order to do so, the plants have developed sophisticated traps that capture the insects and supply them with the much-needed nutrients. We will have a look at the most popular seven carnivorous plants and how to care for them in case we want to plant them in our gardens.
Carnivorous plants: Care
Carnivorous plants are vegetal species that feed on insects and protozoa as opposed to getting their nutrients from the soil via their roots, like the rest of the plants. Due to this particular trait, they have developed quite a unique morphology.
These deadly plants boast a trapping system that varies from species to species, but that always includes tweezer-like spikes, sticky hairs, pitfall traps, or snap traps, in combination with chemical substances. Their bizarre shape and scarcity have turned carnivorous plants into extremely desired houseplants for those less faint of heart. Successful house cultivation requires some special care that we will explain in the following excerpt.
1. Acclimatization
These are delicate plants which require a specific habitat and a certain soil which is why growing them at home usually means problems with the acclimatization. In the first few days of the plant's life, we can use an aquarium and create a terrarium to replicate the exact temperature and moisture conditions. The recommended period of keeping the plant in such a terrarium is approximately one month, after which it can be transferred to a regular plant pot.
2. Light
With only a few exceptions, carnivorous plants require plenty of water, especially the Darlingtonia species or the Drosera one. These two insectivorous plants use the sunlight to intensify the colors of their traps and therefore attract pray easier.
Species such as the Dionaea, Sarracena, Darlingtonia, and Cephalotus need a minimum of 5 hours of sun daily while their more delicate cousins, Drosera and Nepenthes require a sun filter that will prevent the traps from burning.
3. Temperature
Temperature is a relative variable when it comes to carnivorous plants, and it depends if they are a tropical species or not. For example, the genus Sarracenia and the Dionaea (Venus flytrap) go through a process of hibernation with temperatures below 5 degrees Celcius, otherwise, they come out weak in spring and end up dying.
Other plants such as Nepenthes or Drosera are tropical and don't hibernate, and they cannot tolerate temperatures lower than 5 °C. High temperatures are also to be avoided, and the recommended range is between 15 and 25ºC, although it depends on each species.
4. Humidity
One of the most important things to remember when growing carnivorous plants is moisture - they need a lot of it. You can either place a humidifier in the room or add a base plate to your pot and fill it with 2-3cm of distilled or rainwater. Species that require more humidity, such as Nepenthes or the Dionaeas, have a higher rate of survival in a terrarium or an aquarium measuring 40 x 25 centimeters.
5. Substratum
Although carnivorous plants are quite low-maintenance because they adapt to any type of spoil, you need to keep in mind that they tend to grow in soils poor in nutrients. So, try to stay clear of soil that is too rich in minerals as it might kill your plant. The best substratum for carnivorous plants is made out of peat moss, a semi-decomposing moss with a neutral Ph which does two tricks: it's low in nutrients and can hold large quantities of water.
Carnivorous plants: Types and Traits
There are more than 600 species of carnivorous plants classified into 14 botanical genera, however, we will introduce the most popular seven insectivorous plants and what care instructions to follow if you want to grow them at home.
1. Dionaea Muscipula - Venus fly trap
The most popular carnivorous plant is the Venus flytrap, or Dionaea Muscipula, as well as the most sought after by amateur gardeners that desire one of these plants in their houses. It stands out especially because of its unusual morphology, which resembles a tooth-filled mandible that snaps shut as it senses the presence of an insect on its surface.
When relaxed, the plant's trapping lobes resemble two convex structures but when it snaps shut, they create a concave structure that imprisons the insect. The plant's membranes have sensitive hairs that sense the presence of a live pray and trigger the trap to close. As soon as the lobes slam shut, the digestion process starts whereby enzymes are secreted by the same membranes.
Originally from the South West of the United States, the Venus flytrap has adapted to other habitats around the world. In order to survive, it requires a nutrient-free substratum with a mixture of quartz sand and 50% peat moss and distilled or acidic water. A Ph of 5 or 6 is needed, plenty of sun, and no fertilizers. The secret to maintaining a Dionaea Muscipula alive is recreating as much as possible its habitat: maintain moisture at all times, with a minimum 1cm of water constantly. The ideal temperature is between 18 and 26ºC during the summer and between 5 and 10ºC during the winter.
2. Nepenthes - Pitcher plant
This is another fan favorite due to its spectacular shape, a true wonder of nature. It is called a pitcher plant because it is shaped like a pitcher. Originally from the tropical areas of South East Asia, India, Madagascar, and Australia, there have been sightings of monkeys using the plant's cavity as a drinking implement hence the name monkey cup.
At the same time, it's a plant that requires a lot of care, especially since it needs a lot of moisture. Sunlight is not that important, they have to get daily water spraying, and should be pruned in spring. Make sure to change the pot to accommodate the blooming flower and make sure you keep it at a minimum of 18 ºC.
If you manage to keep your carnivorous pitcher plant alive, you will be the proud owner of a spectacular plant with 30cm long green leaves. The plant has a climbing stem that helps it climb and hook in a secure place. At the bottom of this stem, or tendril, the pitchers begin to form a globe or tube-shaped form which has a lid at the top. The inside of the pitcher is filled with a sticky liquid that the plant produces which attracts the insects with its sweet smell. The unsuspecting critter then falls into the liquid and drowns after which the plant digests it.
3. Sarracenia purpurea - Purple pitcher plant
The rich purple color that marks this plant is one of the main reasons why people chose it as a decorative plant and carnivorous-plant enthusiasts collect it. It is original from Texas and Southeastern Canada and it thrives in nutrient-free soil. To successfully care for this plant, you need to consider as substratum a mixture of peat and sand or perlite and make sure to always have a few centimeters of water in the pot saucer as it requires high levels of moisture.
Its trapping mechanism is similar to that of the Nepenthes, its leaves from a type of pitcher filled with a sticky solution. Nectar placed on the edge of the leaf attracts the insects which then inevitably fall into the cup and become digested by the enzymes secreted by the plant.
4. Darlingtonia californica
Also known as cobra lily or a cobra plant, this carnivore boasts an interesting feature - instead of storing rainwater inside its pitcher, it regulates the levels or flushes some water out, according to its needs. Its spectacular appearance attracts many collectors and amateur gardeners alike. The name of this plant - cobra lily, comes from the resemblance that its tubular leaves have with a rearing cobra including even a forked leaf look like fangs or a serpent's tongue.
The trapping mechanism is made out of window-like membranes that filter the sunlight in such a way that once the insects unwittingly enter the orifice at the bottom of the tube, it becomes confused believing it can escape. The prey then keeps walking up the tubular structure only to become permanently trapped and digested. These plants are very sensitive to temperature seeing how in their natural habitat they grow in soil that is fed by cold mountain water, which is why the Darlingtonia californica grows best when its roots are kept cooler than the rest of the plant.
5. Drosera aliciae - The Alice sundew
The Alice sundew has many interesting features that warrant its place in the coveted top 7 carnivorous plants: it is brightly colored and aesthetically pleasing, and it has medicinal properties (especially for alleviating cough). It tends to grow in mountain areas and it is native to the Cape Provinces of South Africa, like Drosera capensis, the cape sundew, and is one of the most common sundews in cultivation.
Its intricate trapping mechanism has transformed this plant into a lethal beauty that few insects have escaped from. Drosera aliciae is also called Alice sundew because its leaves are often reddish and similar in size and are covered with reddish, sticky, glandular hairs that resemble the morning dew.
As you've probably guessed it by now, these sticky hairs are responsible for trapping the prey and then slowly digesting it. They need plenty of distilled water and sunlight in order to grow into healthy plants, kept in temperatures between 20 y 30ºC. The Alice sundew needs a high degree of moisture, between 40 and 70%, with daily water spraying.
6. Cephalotus - The Albany pitcher plant
Indigenous of Australia, this carnivorous plant has a trapping mechanism similar to those of Nepenthes or Sarracenia, with leaves shaped like a pitcher that traps insects and digests them using enzymes.
Compared to the carnivores presented so far, this Albany pitcher plant is smaller and when placed in direct sunlight its leaves turn a bright red. The opening of the pitcher has an inward claw structure that makes it easy to fall inside but difficult to get out.
It's not difficult to grow at home and it can be grown all over the world. The Albany pitcher plant needs a constant temperature of 25ºC and during the winter time, they start hibernating as soon as the temperature drops under 5ºC. A mixture of moss, perlite, and sand should be sufficient for this carnivorous plant, which otherwise requires plenty of moisture and direct sunlight.
7. Pinguicula vallisneriifolia - Butterworts
Moist soil but with few to no vegetation is home to a harmless-looking plant that goes by the name of Butterworts. This inconspicuous plant has large, solid bright green leaves, and a white flower. The green leaves, however, are covered in a viscous liquid that attracts insects and traps them with their sticky effect.
In the case of Pinguicula vallisneriifolia, the insects it attracts are smaller, like flys and mosquitoes which get digested by the same solution that trapped them. This excellent example of carnivory grows on bare rocks which is why a mineral-rich substratum would be fatal for it. It can be planted outdoors in a mixture of peat and perlite, placed in direct sunlight but avoiding temperatures below -2ºC.