Aldrovanda vesiculosa aka Waterwheel Plant

Aldrovanda vesiculosa is extremely challenging to cultivate and recommended only for experienced carnivorous plant growers. Success requires precise control of water chemistry (acidic, low-nutrient, peat-stained water with pH 5.0-6.8), consistent warm temperatures in summer, and careful management of algae growth. The plant is highly sensitive to water quality changes, nutrient loading, and chemical pollutants, making it unsuitable for beginners.

Aldrovanda vesiculosa requires very specific water conditions to thrive. Use only distilled or reverse osmosis water, never tap water. The water should be acidic (pH 5.0-6.8, though it tolerates up to 7.0-7.9), low in nutrients, and rich in tannins from peat and decomposing leaf litter, resembling the color of strong tea. Water temperature should average 80°F (27°C) in summer and can drop to 40°F (4°C) in winter, with a survivable range of 35-90°F. Keep water shallow (6-8 inches deep) in containers of at least 5-10 gallons, or preferably 30+ gallons for best results.

Aldrovanda vesiculosa is a rootless, free-floating aquatic plant that does not grow in soil. However, it benefits from a substrate layer at the bottom of its container consisting of peat, sand, and leaf litter. This substrate releases tannins that acidify the water and provides decomposing organic matter that supports beneficial infusoria cultures (microscopic organisms that help control algae and serve as food for the plant's prey). The substrate should remain undisturbed at the bottom while the plant floats freely in the water column above.

Aldrovanda vesiculosa requires full sun to part sun exposure for optimal growth and trap function. In outdoor settings, it performs best with direct sunlight, though it can tolerate dappled shade when grown among emergent aquatic plants. For indoor cultivation in aquariums, provide bright artificial lighting for 12-16 hours daily. Bright light is essential for developing the striking red coloration in certain strains, particularly the Australian variety, and for maintaining healthy trap function.

Aldrovanda vesiculosa thrives in warm summer water temperatures averaging 80°F (27°C), with tolerable air temperatures ranging from 20-105°F. Winter water temperatures typically average 40°F (4°C), with the plant surviving in water as cold as 35°F. Temperate strains form dormant turions (winter buds) that can withstand temperatures as low as -15°C (5°F) at the water bottom. High temperatures of 29-31°C are required to induce flowering. Tropical varieties prefer year-round warmth and do not require winter dormancy.

As a fully aquatic plant that lives entirely submerged or floating on water, Aldrovanda vesiculosa does not have specific air humidity requirements in the same way terrestrial plants do. The plant naturally experiences 100% humidity at the water surface. For indoor aquarium cultivation, maintaining a lid or cover on the container helps reduce evaporation and maintain stable water levels, which is more critical than air humidity.

Never fertilize Aldrovanda vesiculosa. Like all carnivorous plants, it is adapted to nutrient-poor environments and obtains all necessary nutrients by capturing small aquatic prey such as water fleas (Daphnia), eelworms, and mosquito larvae. Adding fertilizer will damage or kill the plant, promote excessive algae growth, and disrupt the delicate water chemistry it requires. The plant thrives in low-nutrient, acidic water rich in decomposing organic matter from peat and leaf litter.

Aldrovanda vesiculosa is most easily propagated through stem division. Simply cut the main stem in half or just above small offshoots that frequently form along the stem—both pieces will develop into healthy plants if each cutting has at least 3 nodes. Propagation can also occur through turions (winter buds) which naturally detach and overwinter at the bottom before rising and growing in spring. Seed propagation is extremely rare and unreliable, as flowering occurs infrequently (requiring temperatures above 29-31°C) and produces very few viable seeds. Tissue culture is successful but requires laboratory conditions.

Aldrovanda vesiculosa is non-toxic to both humans and pets. This carnivorous plant poses no toxicity risk, though it is not edible or intended for consumption. As an aquatic plant that must be kept in specialized water conditions, most pets would not have access to it under normal cultivation circumstances. The plant's snap traps are designed only to capture tiny aquatic invertebrates and pose no danger to humans or animals.

Aldrovanda vesiculosa produces floating stems that typically reach 6-40 cm (2.4-16 inches) in length, with most plants achieving around 30 cm under optimal conditions. The individual trap leaves are quite small at just 2-3 mm, arranged in whorls of 5-9 around the central stem. Growth rate is moderate to fast during warm summer months, with the plant producing new whorls regularly under favorable conditions. The plant can spread laterally as it branches and fragments naturally, though each individual stem remains relatively narrow at 2-3 mm in diameter.

Aldrovanda vesiculosa has a remarkably wide native distribution spanning four continents: Europe, Asia, Africa, and Australia. It is the second most widely distributed carnivorous plant species after Utricularia. Native populations occur from Western Europe (France, Germany, Poland, Hungary) through Asia (India, Japan, Mongolia, Kazakhstan, Bangladesh, Cambodia) to Africa (Botswana, Cameroon, Chad, Ghana, Madagascar, Sudan) and Australia. However, the species has become extinct in many countries including Austria, Italy, Greece, Korea, and most Baltic states. Natural dispersal occurs primarily via waterfowl, with plants adhering to birds' feet and being transported along migratory routes.

Temperate strains of Aldrovanda vesiculosa require distinct seasonal care due to their natural dormancy cycle. In autumn, as water temperatures drop, the plant forms compact winter buds called turions which sink to the bottom and remain dormant through winter, surviving temperatures as low as -15°C. These can be overwintered outdoors if the water body is deep enough (18-24 inches) to prevent complete freezing, or stored in a peat slurry in a refrigerator at 3°C for indoor cultivation. In spring, when water temperatures rise above 12-15°C, turions naturally float to the surface and resume active growth. Summer care focuses on maintaining warm water (80°F/27°C average), full sun, and managing algae. Tropical varieties from warm climates do not require dormancy and grow year-round with consistent conditions.

Yes, Aldrovanda vesiculosa produces small, solitary white to pale pink flowers that emerge above the water surface, but flowering is quite rare in cultivation. The inconspicuous flowers open for only a few hours before the structure is pulled back beneath the water for seed development. Flowering requires very high water temperatures of 29-31°C and occurs primarily during summer months (June-August) in warm climates. Seed production is sporadic and rarely successful, with flowering being particularly uncommon in temperate regions. Most growers never see their plants flower, as vegetative propagation is far more reliable.

While Aldrovanda vesiculosa is a single species, there are notable geographic varieties. The most striking is the Australian "red" strain (historically recognized as var. rubescens), which displays intense red to purplish coloration when grown in bright sunlight. Temperate strains from Europe and Asia form winter turions for dormancy, while tropical and subtropical varieties from warmer regions maintain year-round growth without dormancy. Plants from different locations also vary in form—some are bushier while others are more slender. Historically, five infraspecific varieties were named (var. vesiculosa, var. australis, var. duriaei, var. rubescens, var. verticillata), but genetic studies show minimal genetic diversity, making these distinctions questionable from a scientific standpoint.

Yes, Aldrovanda vesiculosa can be successfully grown outdoors in USDA zones 5-9, and generally performs better outdoors than indoors. Use large containers of 30+ gallons or outdoor bog pools with shallow water (6-8 inches deep). The container bottom should be below the frost line (18-24 inches deep) to allow turions to overwinter safely without the entire water column freezing solid. Include companion emergent plants like cattails and water lilies, plus floating plants like Salvinia or frogbit to provide shade and support beneficial infusoria cultures. Full sun to part sun exposure is ideal. Outdoor cultivation allows for more natural temperature fluctuations and better supports the plant's seasonal dormancy cycle.

Aldrovanda vesiculosa requires minimal pruning, though occasional trimming can help maintain plant health and encourage growth. Remove any blackened, decaying sections of stems as they naturally die back from the older end while producing new growth at the tip. This is also an opportunity to propagate—cut sections with at least 3 nodes will develop into new plants. During active growth, the plant naturally sheds older portions while extending new whorls at the growing tip, so extensive pruning is unnecessary. The main maintenance task is managing companion plants and controlling algae rather than pruning the Aldrovanda itself.

Maintaining clean water for Aldrovanda vesiculosa primarily involves managing filamentous algae, which is the greatest threat to cultivation. Avoid algae growth by using acidic, peat-stained water with low light levels from emergent companion plants providing partial shade. Introduce beneficial organisms that consume algae without harming the plant: water fleas (Daphnia), tadpoles, and mosquito larvae are excellent choices as they eat algae while occasionally serving as prey for the Aldrovanda. Maintaining healthy infusoria cultures through decomposing leaf litter in the substrate also helps control algae naturally. Never use algaecides or chemical treatments. Partial water changes with fresh distilled or RO water can help if algae becomes problematic, but avoid disturbing the beneficial peat substrate.

Aldrovanda vesiculosa faces few traditional pests or diseases, but several aquatic threats exist. The greatest problem is filamentous algae overgrowth, which can smother plants—control this biologically using Daphnia, tadpoles, and mosquito larvae. Small herbivorous snails may damage plants and should be removed. Fish and larger tadpoles can uproot or consume Aldrovanda and should be avoided. The plant is highly sensitive to water quality issues: nutrient loading, chemical pollutants, and pH changes can cause rapid decline or death. Bacterial or fungal diseases are rare but can occur in stagnant water with poor circulation. Maintaining proper acidic water chemistry (pH 5.0-6.8), low nutrients, and beneficial infusoria cultures provides the best disease prevention.

Slow growth in Aldrovanda vesiculosa typically indicates suboptimal water conditions or temperature. Check that water is sufficiently acidic (pH 5.0-6.8), low in nutrients, and rich in tannins from peat. Water temperature should be warm—growth is fastest at summer temperatures around 80°F (27°C) and slows dramatically below 60°F. Insufficient light is another common cause; the plant needs full sun to part sun for vigorous growth. Algae competition can also slow growth by reducing available nutrients and light. Ensure the plant has access to prey organisms (Daphnia, infusoria) for nutrition. If conditions have been consistently poor, the plant may need time to recover, or propagation from the healthiest sections may be necessary to restart vigorous growth.

Aldrovanda vesiculosa flowers are likely pollinated by small insects, though specific pollinators have not been extensively documented in the literature. The small white to pale pink flowers emerge above the water surface for just a few hours, providing a brief window for pollination before being pulled back underwater for seed development. However, successful pollination and seed production are extremely rare in cultivation, and flowering itself requires very high temperatures (29-31°C) that are difficult to maintain. The plant's primary reproductive strategy is vegetative propagation through stem fragmentation rather than sexual reproduction via seeds.