Floating Forests: The Simple Joy of Growing Duckweed

Duckweed, often seen as a vibrant green blanket on the surface of ponds and slow-moving rivers, is not only the world's smallest flowering plant but also one of the easiest aquatic plants to grow. It is useful to keep water temperatures from rising as much in sunlight, thereby keeping pots and plants that are sitting in the water cooler. We grow it in our flood tables with our Sarracenia (North American Pitcher Plants), Drosera (Sundews), and Dionaea (Venus Flytraps). It also serves as a means for removing excess nutrients from the water.

With its rapid growth rate and minimal care requirements, duckweed has become a favorite among aquarists, hydroponic enthusiasts, and even those seeking sustainable livestock feed.

What is Duckweed?

Belonging to the family Lemnaceae, duckweed comprises several species, with Lemna minor being one of the most common. These free-floating plants consist of one to three leaves, or fronds, with a single root (or root hair) hanging beneath each frond. Duckweed is often confused with its relative, water lentils, which share many of the same growing conditions and uses.

Benefits of Growing Duckweed

- Water Purification: Duckweed can absorb excess nutrients from the water, making it an excellent choice for natural water purification.

- Keeping Water Cool: By preventing light from penetrating past the surface of the water, duckweed minimizes water temperature increase which can be beneficial for other plants growing in the water, such as tray-method grown carnivorous plants.

- Livestock Feed: High in protein, duckweed is being explored as a feed supplement for livestock, poultry, and fish.

- Ease of Growth: It requires no anchorage, reproduces quickly, and can grow in a variety of water conditions.

- Ecological: As a fast-growing plant, duckweed can provide habitat and food for aquatic wildlife.

Growing Conditions

- Light: Duckweed thrives in full sun to partial shade. Adequate light is essential for vigorous growth, although some species can tolerate lower light conditions.

- Water: Calm, still water bodies are ideal, as turbulent conditions can inhibit growth and cause the plants to sink.

- Nutrients: These plants are not fussy about the nutrient medium, often growing well in nutrient-rich water that can be problematic for other plants.

- Temperature: Duckweed grows best in warm temperatures, typically between 50-90°F (10-32°C).

Setting Up Your Duckweed Culture

1. Choose a Container: Any shallow, wide container that can hold water is suitable for growing duckweed. Aquariums, plastic tubs, and garden ponds all make excellent choices.
2. Fill With Water: Use rainwater or dechlorinated tap water to fill your container.
3. Inoculate With Duckweed: Add a small amount of duckweed.
4. Nutrient Addition: A balanced liquid fertilizer at a diluted strength can work well.
5. Maintenance: Skim off excess duckweed as it reproduces to prevent overcrowding. This will maintain water quality and ensure healthy growth.

Harvesting Duckweed

Duckweed can be harvested to feed fish or livestock, or to remove excess nutrients from a water body. Simply scoop out the desired amount with a net or sieve. Remember, it grows back quickly, so regular harvesting is beneficial and encouraged.

Common Challenges

- Overgrowth: Duckweed reproduces rapidly, which can lead to overgrowth. This can be managed with regular harvesting.

- Water Quality: Poor water conditions can harm duckweed growth. Regular monitoring and maintenance of water quality are important.


Growing duckweed is an enjoyable and effortless venture that offers numerous benefits, from water purification to providing a nutritious food source for animals. Its simplicity is matched by its utility, making it a plant that serves multiple purposes while asking for very little in return. Whether you’re a carnivorous plant hobbyist looking to improve your water-tray environment, an aquarist eager to maintain a healthy tank, or an innovator exploring sustainable feed options, duckweed is a resilient and worthy addition to your green endeavors.

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