Propagation by Rhizome Division.
Many aquatic plants propagate by dividing the rhizome or tuber. Many plants form a more or less branched and complex rhizome, which in their natural habitat acts as a storage organ helping to overcome unfavorable vegetative periods. For example, the rhizome of Anubias barteri is very long, relatively thin, and regularly branching. In contrast, the rhizomes of mostly branching Echinodorus species are strikingly thick, only a few centimeters long, and branching is observed only occasionally in strong parent plants. Plants that propagate by rhizome division include species belonging to the water lily family (Nymphaeaceae).
The division of a plant’s rhizome should be done in such a way as not to destroy the parent plant. In a plant with a creeping rhizome, no more than 30% of its total 
length can be cut off. To increase the propagation rate, long rhizomes can be cut with a sharp knife into separate pieces 2-3 cm long, and it is desirable that each section retains several buds. Each such piece should have one or two buds with a sufficient amount of nutrients from which young plants will form. For germination, the rhizome pieces are placed in the aquarium water. These pieces can be left on the water surface in the aquarium with intensive lighting until new plants develop from the reserve (dormant) buds. With the development of leaves and roots, the rhizome is gradually planted deeper into the substrate.
In Anubias species, such propagation by rhizome division is quite productive, but in Echinodorus species, it does not always lead to success. Propagating plants in this way can only be recommended to experienced aquarists and only when strictly necessary. The fact is that separated parts of the rhizome, until young plants appear on them, easily become diseased and often begin to rot. In addition, plants formed on separated parts of the rhizome develop slowly at first.
To prevent rotting of the rhizome parts and accelerate the formation of young plants, freshly cut rhizomes can be treated with biogenic stimulants. Heteroauxin is most widely used. The rhizome is immersed for 20 minutes in a solution prepared by dissolving one heteroauxin tablet in 1 liter of water. Other stimulants can also be used in accordance with the instructions attached to them.
Rhizome division is a common propagation method for Anubias and some Echinodorus species that store nutrients in a thick, creeping rhizome. Basically, such plants develop relatively slowly and form a noticeable rhizome only after about a year. Dormant buds awaken in certain places, giving life to new small bushes that can be separated from the parent plant by carefully breaking the rhizome. Even if you break the latter when there are no shoots yet and let it float on the water surface, after some time it will certainly give life to new small plants.
After such a plant produces several leaves and roots, it is separated with a sharp knife along with a piece of rhizome and planted in the substrate. With this propagation method, it is important to prevent the rotting of the unprotected root part. When transplanting an old rhizome of a plant with a long rhizome, a piece can be cut off and pressed to the substrate. Over time, a daughter plant will form from the dormant buds.
It is much better not to cut such a plant on the parent rhizome, but to wait until the new plant forms an independent root system. Such a plant can then be easily separated from the main rhizome and planted in the substrate. New lateral shoots (plants) will then quickly form on the parent rhizome. The appearance of the first daughter plants may take a long time, up to 2 years, but this propagation method is much more productive than root dissection.
Aponogeton species can be propagated by dividing the rhizome or tuber using a sharp knife (Aponogeton ulvaceus, Aponogeton madagascariensis). To do this, the tuber or rhizome of a well-developed bush is divided with a sharp razor blade into 2-4 parts, making vertical cuts through the growth point, and charcoal powder is rubbed into the cut plane. The tuber has several growth points (developing young leaf rosettes).
It is best to choose the cut location so that each part gets the maximum share of the tuber – the nutrient supply – while the cut length (and therefore the plant’s wound) is minimal. These parts are planted in a well-lit place. After recovering, the plant produces young plants from the buds. Propagating Aponogeton by dividing a tuber at the beginning of its growth stage is entirely feasible.
In bulbous plants, such as Crinum thaianum, daughter bulbs form from the axillary buds of the bulb in close proximity to the parent plant, which are then separated and develop into daughter plants. After forming several leaves, the plant is dug up and planted in a new location. This formation process is slow. From the moment the young plant is planted until the appearance of its first offsets, at least 3-5 years pass.
