Carnivorous plants — those creepy little beings that devour insects — are fun to add to your houseplant collection, especially around Halloween. You can watch in fascination as they attract, trap, and slowly digest their prey.
What Are Carnivorous Plants?
Carnivorous plants are just like other plants. They need sunlight (lots of it), carbon dioxide, and water to make sugars and starches which are their basic sources of energy. But these plants also do something else — they supplement their diet with fresh insect meat that they trap and digest.
Why? Because they don’t get the other nutrients they need, such as nitrogen, from the poor, highly acidic soil where they are native. As a result, they’ve evolved to enhance their diets with proteins from living insects or spiders. These plants have developed modified leaves with special mechanisms to trap insects. The unsuspecting, trapped creatures are slowly digested by way of enzymes or bacteria.
What kinds of carnivorous plants are there, and how do you care for them? They need you to understand them and give them what they need since they’re pretty specialized. Read on for more information.
Kinds of Common Carnivorous Plants
There are approximately 700 species of known carnivorous plants, but the three most common types that you can grow as houseplants are tropical Sundews, Venus Flytraps, and the tropical pitcher plant called Nepenthes, or Monkey Cups.
Sundews (Drosera sp.)
Sundew Photo by Yoksel Zok
Sundews are native to temperate and tropical climates worldwide. The cold hardy species can be grown successfully outdoors, but tropical Sundews are the ones best suited as indoor houseplants.
Their unique method of catching insects is by the flypaper method. They have spindly or spoon-shaped leaves with drops of shiny glue at the ends of long, red tentacles that attract and trap their prey. When they sense a struggling insect mired in the glue, their leaves bend to close over their prey and slowly digest it.
Venus Flytraps (Dionaea muscipula)
Venus Flytrap Photo by Noah Howell
Venus Flytraps use a spring-trap mechanism to catch their prey, and are among the most popular insect-eating plants on the market because they’re fun to watch. Their specialized leaves are divided into two lobes that are hinged on the bottom and have three sensitive trigger hairs on each lobe. When an insect lands on the leaves and trips one of the hairs, the lobes snap shut in less than a second, trapping the insect. Then it takes them a leisurely one to two weeks to digest their prey.
Venus Flytraps are cold hardy plants and are only native to North and South Carolina, although they’re grown all over the world. They are happier growing outdoors, but can be grown successfully indoors under the right conditions.
Monkey Cups (Nepenthes sp.)
Pitcher Plant Photo by Lauren Howell
Monkey Cups are vines with an unusual anatomy. They are a type of pitcher plant with jug-shaped collection traps that hang from tendrils growing out of the midribs of strap-shaped leaves. The traps, or pitchers, have nectar just below their rims to attract insects. When critters reach down to drink the nectar, in they go!
The downward-growing hairs or the slippery, waxy coating on the insides of the traps makes it impossible for them to climb out once they’ve fallen in. The insects tire, and finally fall down into the liquid enzyme bath and are slowly digested. The traps are yellow, purple, or a mixture of both, and all of the species are native to tropical Asia.
Carnivorous Plant Care
Most carnivorous plants grown indoors need the same kind of care. They have the reputation of being difficult to grow, but the reason that so many die is that they don’t get the right care. If you pay close attention to their needs, you should be able to successfully grow these little curiosities.
Light - Carnivorous plants need lots of light in order to make enough sugars and starches to run their insect-catching machines. Venus Flytraps need 14 to 16 hours of bright sun daily during the growing season. Since that’s a difficult amount of light to provide indoors, put them on your sunniest windowsill and then supplement with a daylight plant bulb that is in the 5500K - 6500K color range.
Tropical Sundews grow well on a bright windowsill with 4 or more hours of direct sunlight and bright indirect light the rest of the day. Nepenthes, on the other hand, prefers 14 to 16 hours of filtered, indirect light. As with Flytraps, supplement the available sunlight with a daylight plant bulb. Insufficient light is the main cause of the demise of these fascinating plants, so it’s critical that they have enough light.
Temperature - Carnivorous plants are happiest in temperatures that are between 60⁰ and 80⁰ F. They should be kept away from cold windows in the winter, and should also not be allowed to cook in the hot summer sun. Other than that, normal indoor temperatures are one less worry for their care.
Soil - All carnivorous plants need nutrient-free, acidic soil without any fertilizer or supplements. Use a soilless mix of 1 part peat moss to 1 part perlite or coarse sand that will be loose enough to allow good drainage and aeration, but also will allow for good moisture retention. A layer of pebbles on top of the soil mix or some sphagnum moss will keep the loose peat from escaping the pot. DO NOT use general houseplant soil, garden soil, or any sort of fertilizer. It will kill your plants within weeks.
A Word about Pots - Plastic pots are best since they retain the most moisture, but it’s very important that they have drainage holes! Read on and you’ll see why.
Water - Carnivorous plants need pure water with no minerals or a very low mineral count (less than 50 ppm), such as distilled water from the grocery store or rain water. Bottled or spring water are not good choices because of the mineral content, and it’s risky to use tap water unless you have it tested and you’re sure it has a low mineral count. Boiling tap water will not rid it of minerals either — it will only concentrate them.
Their soil needs to be consistently moist, but not soggy. The way to accomplish this is to set the pot in a dish with a half to a quarter inch of water in it and allow the soil to soak up the water through the drainage holes. Nepenthes in hanging pots can be taken down and set in a dish of water, or they can be watered from the top as long as the water can run out of the drainage holes. Be sure to let the soil breathe before watering again, but keep the top of the soil damp to the touch at all times.
Humidity - Sundews, Flytraps, and Nepenthes all need humidity to live, tempered with air circulation. Sundews will refuse to make dew, Flytraps won’t make traps, and Nepenthes won’t even make pitchers if the humidity is too low.
Ambient humidity in the house may be enough, but all the plants will benefit from daily misting with pure water, especially in the winter when the heat is on. An open terrarium or glass jar or bowl with enough air circulation will give the plants enough humidity, but be careful not to overwater them. Soak up any extra water collecting in the bottom of the terrarium with a clean paper towel.
Feeding Them - Carnivorous plants usually can attract insects or spiders on their own. You don’t need to supply them with multiple insects on a daily basis! One fresh, live bug a week is all that they can digest at once, and all they need. NEVER feed them meat, or any kind of people or pet food. It will kill them since it isn’t what they can digest.
Playing with Them - As fun as it is to watch a Venus Flytrap snap shut, or a Sundew curl up to secure a struggling insect, it’s not nice to play with them. The leaves of Flytraps will only snap shut 7 - 10 times before they die off, and Sundew leaves will refuse to make dew if they are tampered with. Remember, the plants work hard to keep their traps in shape, so we need to leave them alone to do their job.
The important thing about growing carnivorous plants indoors is to pay close attention to their requirements. In general, if you take care of their need for lots of light, consistent moisture, enough humidity, and the right kind of soil and water, you’ll be on your way to successfully nurturing these creepy little plants.
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