Water Lettuce

Description

• Water temperature: Water lettuce thrives in warm water, ideally between 70°F and 80°F. While it can tolerate temperatures as low as 50°F, colder temperatures will stunt its growth. It’s sensitive to cold and frost and won’t survive freezing conditions outdoors.
• Sunlight: Water lettuce prefers full sun exposure, meaning at least six hours of direct sunlight daily for robust growth. However, it can tolerate partial shade, especially in hot climates where afternoon shade can protect it from scorching. In low-light conditions, growth may slow, and leaves may appear darker green.
• Water parameters: It prefers neutral to slightly alkaline or acidic water, with a pH between 6.5 and 7.5. Soft to moderately hard water is best, and it’s sensitive to minerals like lime and excessive salt. Water lettuce absorbs nutrients directly from the water.
• Container or pond: Water lettuce can be grown in contained water gardens, ponds, or even pots both indoors and outdoors. 

• Purchase or acquire: Water lettuce is readily available in garden centers and shops specializing in aquatic plants.
• Acclimation: If you receive plants by mail order, they may not look their best initially. Allow them to recover in a smaller pot placed in a shady spot for a few days before introducing them to the larger water garden or aquarium.
• Planting: Simply place the plant on the surface of the water, ensuring the roots face downwards.
• Propagation (vegetative): Water lettuce propagates easily through vegetative reproduction using stolons or runners. These horizontal stems produce small “daughter” plants that can be gently separated from the mother plant and replanted.
• Propagation (seed): While less common, water lettuce can also be grown from seed. Bury the seeds lightly in sand, cover with water, and maintain the water level above the sand until they sprout. 

• Fertilizing: Water lettuce can be fertilized periodically to ensure adequate nutrients, especially if the water is low in nitrates. You can add a balanced fertilizer directly to the water or place the plants in a tub with liquid fertilizer for a few hours.
• Trimming and pruning: Water lettuce grows rapidly and can quickly cover the water’s surface, potentially blocking light and disrupting the ecosystem. Regularly remove excess plants or prune runner plants to manage its growth.
• Pest and disease management: Water lettuce is generally hardy but can be susceptible to issues like aphids, caterpillars, spider mites, and root rot. Signs of nutrient deficiency include yellowing or browning leaves, which can be addressed with fertilization.
• Overwintering: In colder climates (outside USDA Zones 9-11), water lettuce can be grown as an annual or overwintered indoors. To overwinter, place the plant in a container with water in a warm area (above 50°F, ideally around 70°F) with bright light. However, replacing it annually may be more cost-effective as it grows quickly and is relatively inexpensive. 

• Invasiveness: Water lettuce is considered an invasive species in some areas due to its rapid growth and ability to form dense mats. If growing outdoors, contain it within a pond liner or regularly remove excess plants to prevent it from spreading uncontrollably.
• Toxicity: Water lettuce is toxic to people and pets. If ingested, contact poison control immediately.