Culture
Strict adherence to the cultural needs of this plant is essential. Venus fly trap appears to be winter hardy to USDA Zones 7-10, but with adequate winter protection may also survive winters in USDA Zones 5 and 6. In residential areas where winter hardy, plants are best grown in the consistently moist soils of a bog garden. The bog garden should be prepared in advance of planting. In the St. Louis area, the bog garden should be sited in a protected location with a winter mulch in full sun to part shade. Bog gardens basically need an acidic, humusy, unfertilized, somewhat mucky soil that is constantly damp. Soils must never dry out. Plants flower in spring, produce new leaves (“traps”) in spring-summer and then mostly die back as winter approaches. Winter dormancy is usually triggered in fall when temperatures begin to fall below 50 degrees F as day lengths shorten. Soils should be mulched in winter with pine needles or leaves to protect the rhizomes from cold temperatures. If a bog garden is not available, the next best option may be to grow plants in pots/containers placed outside on a sunny deck or patio areas. Use a mixture of sand and peat moss. Containers should be placed in a tray of water that helps keep the soil constantly moist. It is best to use rain water, distilled water, or reverse osmosis water. Containers may be overwintered by inserting them to the rim in soils in protected locations and then covered with mulch. Dig up containers in spring to place back in sunny areas. Containers may also be brought inside in fall for overwintering in a sunny but cool area (southern window) with temperatures of 40-50 degrees F. Plants may also be grown in terrariums where humidity and moisture can be controlled. Plants often do not grow well as houseplants. Propagate by division in spring.
Noteworthy Characteristics
Dionaea muscipula, commonly called Venus fly trap, is perhaps the best known of the carnivorous plants that are native to the southeastern United States. It is native to coastal plain areas in southeastern North Carolina and eastern South Carolina (all within a 100 mile radius of Wilmington, N. C.), where it is typically found in sandy, acidic, boggy sites in marshlands, wet grasslands and savannas. Separate populations have naturalized in Florida and the New Jersey Pine Barrens. From a rhizome, this herbaceous perennial produces a low-growing rosette (to 5” tall and 8” wide) of up to eight bristly, spreading, basal leaves (each to 1-5” long), with each leaf (“trap”) being folded into two hinged lobes with bristly edges. Plant nectar lures insects into the trap. Each lobe has three sensitive trigger hairs. When an insect touches the trigger hairs, the trap slams shut imprisoning the insect until it dies and until subsequent digestion (enzymes are secreted by the leaves) takes place over the next 4-10 days. The trap then opens up in search of new prey. Cup-shaped, white flowers in umbels of 4-10 bloom in spring (May-June) on leafless stems rising well above the foliage to 12” tall. Fruits are egg-shaped capsules. Plants can be grown from seed, but it usually takes several years for them to develop. This is an endangered species which cannot be legally collected from the wild. It is also listed in Appendix II of the Convention on International Trade in Endangered Species (CITES).
The genus name Dionaea comes from one of the Greek names for Venus.
The specific epithet muscipula comes from Latin and means "mousetrap".
'Cup-shaped' has rounded cup-shaped traps. It grows 0.5 to 1 ft. tall and 0.5 to 0.75 ft. wide. The cultivar name could not be verified.
Problems
Watch for aphids and spider mites. Black spot may appear. Wild populations are threatened by habitat loss and poaching. Only purchase nursery propagated plants from reputable growers.
Uses
Bog gardens. Also may be grown in containers, terraria (indoors under grow lights) or greenhouses. Growth as a houseplant is possible but can be difficult because of the need for growing season sun, humidity and winter dormancy. May be grown outside in low spots or other continuously moist locations, but this can also be difficult and is not recommended.