Duckweed - Lemna

General duckweed

Duckweed is a floating plant found in all the temperate zones of the globe. It produces small green leaves, rounded or oval, with a diameter close to a few millimeters, up to 4-5 cm of the largest species; every single leaf constitutes an entire plant, being endowed with a single small root. These plants remain completely floating on the surface of the water, being slightly swollen. In spring they produce very small, inconspicuous flowers, which will be replaced by small fruits containing a single seed. These plants can become weeds and are also grown in aquariums.
One of the characteristics that distinguish these plants is their ability to multiply their structure in just three days. Moreover, they easily absorb the nitrogen present in the water in which they reside and also absorb carbon from the atmosphere. This aspect makes it an excellent purifying plant capable of eliminating excess nitrates from the water thanks to its absorption. This is why the word of water or duckweed is used in small basins, wells and collection tanks to reduce the amount of nitrates. Nitrates are one of the most polluting compounds for soil and water.
A clarification, under the name of duckweed, different species are grouped that apparently have very similar characteristics as Lemma gibba and other plants of the Lemnaceae family.


Lentils are preferably grown in slow-moving watercourses, or in shallow lakes or marshes; the ideal temperature for growing duckweed is between 20 and 30 ° C; in cold or excessively hot conditions, small plants sink into the water and anchor to the bottom of the water. In aquariums they develop at their best, but they must be controlled to contain their exuberance.
The development of these plants, when the ideal conditions exist, is really rapid and in a few days you can get coats of water lentils with a very pleasant ornamental effect.


In spring these plants tend to self-reproduce: every single leaf, over a few days, splits, producing a new specimen, which quickly detaches from the mother plant; to colonize a pond it is sufficient to release some lemna leaves in the water, in the spring, they will quickly produce a large colony. These aquatic animals also reproduce by seed, maintaining the submerged seedbed until germination took place. It is also possible to buy the seeds of these plants directly in nurseries or in the nearest garden centers. Once grown, the seedlings can be taken and placed in any small lake or stream that you want to colonize with duckweeds.

Duckweed: Pests and diseases

Generally the duckweed they are not affected by pests or diseases and do not require special attention. Furthermore, if we want to grow these plants, the technique to be used is very simple. In fact, it is not necessary to have a specific soil where it can grow or a particular irrigation as they grow immersed in water and always have the quantity necessary for them to develop.