Caren White is a Master Gardener and instructor at Home Gardeners School. She has been associated with Rutgers Gardens for over a decade.
It’s no secret where my green thumb comes from. My mother had gorgeous flowerbeds outdoors and a huge collection of houseplants indoors. One my favorite houseplants was her Venus flytrap.
What are Venus Flytraps?
Venus flytraps (Dionaea muscipula) are carnivorous plants that are native to North and South Carolina. There are other naturalized populations in Florida where they have been introduced. The plants grow in wetlands and bogs, thriving on the moisture and poor soil. In fact, their ability to consume insects evolved to compensate for the lack of nutrients in their native environments. The plants are small, growing low to the ground in a rosette of leaves that is usually 5 inches in diameter. When they flower, the flower stalks can be almost a foot tall. The reason that the flower stalk is so tall is so that the insects that pollinate the flowers do not get caught and eaten in the “traps” at the ends of the leaves. Once the flowers are pollinated, they produce tiny black seeds.
The “traps” are located on the ends of the leaves. When they are healthy, they are red on the inside and convex when they are open. There are long hairs along the edges of the traps and smaller hairs on the insides. When an insect lands on a trap, it stimulates the hairs along the edges to start the process of being trapped and eaten. When the trap is closed, it becomes convex and acts like a stomach, holding the prey inside.
How do Venus Flytraps Trap and Eat Insects?
When an insect lands on a trap, its movement is detected by the hairs along the edges of the trap. Two or more hairs must be stimulated to start the process. This is to prevent the trap from snapping shut every time there is a stiff breeze or a small piece of dust lands on it. Once the trap closes, the process of digestion doesn’t begin unless the prey is moving. If for some reason, a dead insect falls into the trap or the prey that has been trapped is too large for the trap to close completely, within 12 hours, it will open again releasing whatever fell into to it.
If the prey is an appropriate size and live, the trap will close completely over it. The stimulation of the tiny hairs on the inside by the prey’s movements releases the digestive enzymes that will dissolve the insect. It takes about 10 days to completely digest the insect. All parts of the insect except the outer exoskeleton will be dissolved and used as nutrients by the plants.
What do Venus Flytraps Eat?
Carnivorous plants have specialized diets that depend on their size. Venus flytraps are small so they are limited to eating small insects. Their diets consists of beetles, ants, spiders, and small flying insects such as flies. They only eat live prey so if they are grown indoors where there are no live insects available, you will have to supply them with live prey or manually stimulate the traps enough that they will accept dead prey. Stimulation of the hairs is what tells them that whatever is caught in their traps is alive.
How to Grow Venus Flytraps
Venus flytraps are semi-tropical plants. They are hardy in zones 8 through 10. In colder growing zones, they must be grown indoors. Because they need humidity, most people grow their plants in terrariums. You can use an old aquarium or even an unused fish bowl.
The plants like warmth, but you must be careful when growing them in glass containers in the sun because they can overheat, killing your plants. You will need to move your terrarium away from direct sunlight to avoid this. During the winter, you should keep your terrarium away from cold drafts from windows and doors that open to the outside. The plants cannot tolerate very cold temperatures.
Soil is critical. In their native environments, they grow in very poor soil with almost no nutrients so normal potting soil will kill them. Mix your own soil using 1/3 sand and 2/3 peat moss. This will provide good drainage and no nutrients. Obviously there is no need to fertilize your plants. It’s a good idea to repot your Venus flytrap every few years and give it fresh soil.
Keep your plant moist, but not constantly wet or it will rot. Rather than tap water which can contain minerals, water your plants with distilled water which has no minerals or rain water that you have collected outdoors.
Because they are semi-tropical plants, Venus flytraps can’t survive northern winters, but they do have a period of dormancy each year between November and February during the dark days of winter. The foliage dies back to the ground and the plants can appear to be dead. During this period, it’s important that you keep your plants in an environment that is between 35⁰F and 50⁰F, mimicking the winters of its native habitat. In the spring when the days start to grow longer, you can gradually warm up your plant.
With proper care, your Venus flytrap can live as long as 20 years.
How to Feed Your Venus Flytrap
If you grow your Venus flytrap outdoors, it will naturally have enough insects to eat. If you are growing it indoors, where there are no insects, you will have to provide it with live prey. The easiest way to do this is to release live flies into their terrarium. Eventually, the flies will find the plants and be eaten. If you do not have access to live prey, you can use dead insects, preferably ones that have died recently. Because they won’t move and stimulate the trap to close and digest them, you will have to provide the movement. Place the insect in the trap and gently rub the hairs on the edges of the trap to let the plant know that there is prey in the trap. When the trap closes, you will need to gently rub it and squeeze it to mimic the movements of live prey, stimulating the plant to release the digestive enzymes.
Fortunately, the plants do not need to eat every day. They can actually go without a meal for as long as 30 to 60 days.
How to Grow Venus Flytraps From Rhizomes or Seed
Very few nurseries sell Venus flytraps. Fortunately, you can order them online or from a catalog. You will receive a rhizome. Plant it in your sand and peat moss mixture with the root side down. Keep the soil moist and within a week or two, you should observe the rosette of leaves begin to grow.
Interestingly, the plants never have more than 7 leaves in their rosette. If your plant has more than 7 leaves, it has propagated via that rhizome that you initially planted. Now you have two plants! You can separate them by carefully digging up the rhizome and cutting off the piece that has the new growth and replanting it elsewhere in your terrarium.
You can also grow the plants from seed. Sow the seeds on the surface of your sand and peat moss mixture. Don’t cover them. They need sunlight to germinate. Keep them moist and warm. Germination will only occur if the air temperature is between 75⁰F and 85⁰F. Your seeds should germinate within 2 weeks.
© 2018 Caren White
Bronwen Scott-Branagan from Victoria, Australia on November 15, 2018:
Thank you for an interesting article. The photos are great, too. They must have taken a while.
Heidi Thorne from Chicago Area on November 14, 2018:
I think these are some of the most fascinating members of the plant world! They seem to be a plant+animal hybrid. Thanks for sharing the great info and Happy Thanksgiving!