Venus flytrap

What they are

Dionaea muscipula is the only species in its genus, part of the sundew family, Droseraceae. It grows as a flat rosette from a short white underground stem. A mature rosette is 15 to 20 cm (6 to 8 in) across with leaves 5 to 13 cm (2 to 5 in) long including the flattened stalk, and an adult trap is about 2.5 cm (1 in). Each leaf ends in the trap: two hinged lobes edged with stiff bristles, each lobe carrying three fine trigger hairs. Touch two hairs, or one hair twice, in quick succession and the lobes snap together in well under a second. A single touch does nothing, which stops raindrops and debris from closing the trap for no reward.

The counting goes further. Two electrical signals close the trap, and only the repeated signals of struggling prey switch on the glands that flood it with digestive fluid. A trap that shut on nothing opens again the next day. A fed trap seals for several days, reopens around the remains and works a few more times before the leaf blackens; poking traps for fun shortens that life.

In spring a wiry stalk 10 to 30 cm (4 to 12 in) tall carries small white flowers. The leaves change through the year, low and broad-stalked in winter, taller and narrow-stalked around flowering; stalk length and the red inside the trap vary between plants as well as with light. John Ellis published the name in 1768.

Where they grow

The whole native range is one corner of the Carolinas: historically the outer coastal plain from Beaufort County, North Carolina, to Charleston County, South Carolina, and inland to Moore County. The plant grows in wet, sandy, peaty ground in longleaf pine savannas and in the seepage zones between them and the shrub bogs called pocosins, where the soil is saturated but not flooded and the sun is full. Fire keeps it open: the species is very sensitive to shade and drought and declines where its habitat does not burn about every five years. The care below is a translation of this: full sun, a wet but airy root zone, water with almost nothing dissolved in it, and a cold winter.

The range has shrunk through drainage, development and fire suppression. Digging wild plants has been a felony in North Carolina since 2014, and the U.S. Fish and Wildlife Service, reviewing a 2016 petition, found in 2023 that federal listing was not warranted. Nothing you buy needs to come from the wild: there are roadside populations managed for nursery seed, and commercial plants are raised in sterile culture. The species has naturalised in the Florida panhandle, southern New Jersey and northwestern Washington.

The range in cultivation

One species, but the International Carnivorous Plant Society, the registration authority for carnivorous plant cultivars, lists more than a hundred registered Venus flytrap names. All need the same care:

• Typical plants. Green, with a red flush inside the trap in good light. Most unnamed plants are these.
• All-red plants. ‘Akai Ryu’, sold in English as ‘Red Dragon’, was raised from tissue-cultured seedlings at the Atlanta Botanical Garden and described in 1996; it is burgundy throughout in sun and holds an RHS Award of Garden Merit.
• All-green plants. ‘Justina Davis’, registered in 2006, has no red pigment even in full sun.
• Giants. ‘B52’, bred by Henning von Schmeling and registered in 2006, has traps up to 5.7 cm (2.25 in).
• Novelty traps. ‘Dente’ has short jagged teeth, ‘Fused Tooth’ has bristles joined by webbing, and ‘Cupped Trap’ has lobes fused at the tip so the trap cannot close. All arose as tissue-culture mutations. Forms with non-working traps cannot feed themselves and need foliar feeding.

Tissue culture produces almost all commercial flytraps, and that is no mark against a plant: only the best clones, perhaps one seedling in a thousand, are multiplied this way.

Growing them

Light

Full sun, six or more hours of direct light. Indoors, aim for 15,000 to 25,000 lux of white LED light for about 14 hours a day, far more than a winter window gives. Some growers keep flytraps on a sunny windowsill, but in temperate latitudes it does not make a good windowsill plant.

Water

Rain, distilled or reverse-osmosis water. Tap water is usable only below about 90 parts per million of dissolved solids. Stand the pot in a shallow tray in the growing season, let it dry briefly between refills, and keep the water level more than 5 cm (2 in) below the surface, which means a tall pot. Damp, not wet, in winter.

Growing medium

Sphagnum peat moss and washed silica sand in about equal parts, or pure sphagnum moss. Perlite and pumice are best avoided because they can carry salts; some growers use 4 parts peat to 1 of perlite, so rinse it well if you do. No fertiliser, lime or compost. Repot into fresh medium about once a year in late winter.

Temperature

Warm summers are fine with wet roots; winters should be cold. In USDA zone 9 and warmer the plant lives outdoors all year. In zones 7 and 8 a fully dormant plant survives a week frozen solid if it does not dry out; zones 7 to 10 count as hardy, 5 and 6 with protection. Colder than that needs a cold greenhouse or deep mulch. In Britain’s wet winters it is rated H3 and needs protection below about -5 °C (23 °F).

Dormancy

From late autumn the plant shrinks to a small rosette, traps blacken and growth stops for about three months. Outdoor plants rest on their own. Most growers hold that every flytrap needs this rest; plants under strong artificial light all year do not, and chilling an indoor plant in the refrigerator is a waste. Both views are right: under 14 hours of strong light a plant keeps growing, but on a windowsill in short winter days it cannot, and there the cold rest is what keeps it alive.

Feeding

Outdoors it feeds itself. Indoors, give a trap a live insect, a piece of rehydrated dried bloodworm or an insect-based fish food, no bigger than a third of the trap, and stroke the closed lobes so that dead food is digested. Regular feeding makes a noticeably larger plant, and a fed seedling matures in about two years instead of five. Some growers use a dilute foliar fertiliser once or twice a month indoors, but flytraps do better without fertiliser of any kind: feed the traps, never the soil.

Common mistakes

• Tap, bottled or softened water; the damage shows weeks later.
• Leaving the plant in the sealed container it was sold in, or on a dim windowsill.
• Setting off the traps with a finger.
• A warm winter indoors with no rest, repeated for two or three years.
• Fertiliser, plant food or meat.
• Pulling off blackened leaves: cut them instead, since tugging a freshly dead leaf can lift the plant out of the pot.

Which to start with

With one species the choice is about condition, not name. A nursery-raised plant of the typical form, bought in spring from a seller who keeps it in good light and pure water, is the best start. ‘Akai Ryu’ and ‘B52’ are good second plants, the first for colour and the second for size.

Be wary of the flytraps sold in supermarkets and hardware stores in sealed plastic domes or cubes. The plant inside is usually a sound tissue-cultured clone, but it has sat for weeks in deep shade with no air movement, often in moss watered with whatever was to hand, and its traps have been triggered by every passing customer. If you buy one, take it out of the container the same day, repot it, move it to the strongest light you have and switch to pure water. Leave the novelty cultivars until you have kept an ordinary plant through a winter, and never buy a plant described as wild-collected.

Going further

A flytrap that has been through two winters with you can be divided, and it will set seed if you move pollen between flowers; leaf pullings and flower-stalk cuttings also work. The propagation entry for Dionaea sets out each method; the species profile has the detail. The natural next plants are the American pitcher plants, or a sundew such as Drosera capensis, which needs no dormancy at all.