Taro (Colocasia esculenta) is a tropical plant cultivated globally for its starchy corm and edible leaves. It is a centuries-old staple food in regions including the Pacific Islands, Africa, and Southeast Asia. Unlike many garden plants that suffer in saturated soil, taro is one of the few major crops that thrives in standing water. Cultivating taro in flooded conditions is often the preferred method in traditional agricultural systems, confirming its suitability for aquatic environments.
Taro’s Natural Adaptations to Wetland Environments
Taro’s ability to thrive in flooded conditions stems from specialized internal structures that manage the challenge of low oxygen in submerged soil. Flooding rapidly depletes oxygen available to plant roots, causing death and rot in most terrestrial species. Taro overcomes this by forming a tissue called aerenchyma, which consists of large, air-filled channels within the stem and roots.
This spongelike tissue acts as a built-in snorkel, allowing oxygen to diffuse from the air-exposed leaves down to the roots and corms below the waterline. This oxygen supply is crucial for root respiration and survival in the anaerobic mud. Furthermore, the roots possess a barrier to radial oxygen loss (ROL), which directs the limited oxygen supply toward the root tips. This focused oxygen release helps neutralize toxic compounds like iron and manganese that accumulate in waterlogged soil.
Specific varieties of taro have been selectively bred for distinct growing conditions. Wetland taro, often grown in flooded paddies for higher yields, is adapted for continuous submersion. Dryland taro varieties are better suited for well-drained, upland soil, though they still require consistently moist conditions.
Practical Approaches to Water Cultivation
Water cultivation of taro includes traditional large-scale production and modern small-scale methods. The most ancient and widespread method is the paddy system, known in Hawaii as a loʻi, which involves growing taro in banked fields continuously flooded with water. In this traditional setup, the water level is gradually raised as the plant grows, typically maintained at 4 to 6 inches above the soil surface. Constant, slow-moving water flow is often used to prevent stagnation, which helps maintain higher oxygen levels and reduces disease risk.
A more modern, high-intensity method is Deep Water Culture (DWC), a form of hydroponics where the plant roots are suspended directly in a nutrient-rich water reservoir. For a small-scale DWC setup, the taro corm is started in a net pot filled with an inert medium like rockwool or clay pebbles. The net pot is placed into the lid of an opaque reservoir, allowing the roots to hang into the nutrient solution. The most important component is an air pump and air stone, which aggressively bubble the water to saturate it with oxygen, preventing the roots from drowning.
For ornamental or indoor growing, taro can be kept in a simple container or jar of water. A taro corm or whole plant can be placed into a large, non-draining pot filled with heavy loam soil, and the container is then filled with water until the surface is submerged. This method mimics the saturated conditions of a pond edge and is popular for growing the plant’s large, decorative leaves.
Maintaining Optimal Conditions for Aquatic Growth
Successful aquatic taro growth requires careful management of environmental factors, starting with water temperature. As a tropical plant, taro thrives in warm conditions, with an ideal temperature range between 70°F and 85°F. Temperatures below 68°F slow growth considerably, and cold water can lead to root damage and rot.
Taro is a heavy feeder, especially in aquatic systems where nutrients are not supplied by traditional soil. For hydroponic or DWC systems, a balanced commercial nutrient solution is necessary, often formulated higher in nitrogen to support the plant’s massive leaves. Regular monitoring of the water’s potential of hydrogen (pH) is also necessary, with an optimal range between 5.5 and 7.5 to ensure maximum nutrient uptake.
A high light intensity is required for the plant to produce a healthy corm and large leaves. Outdoors, taro needs six or more hours of full sun daily, though partial shade is beneficial in regions with intense afternoon heat. Indoors, the plant must be provided with powerful grow lights or a location near a south-facing window. Consistent oxygenation in the water, either through mechanical aeration in DWC or constant flow in traditional paddies, promotes robust growth.