Rooting begonias using only water is a highly accessible and popular propagation method. The begonia genus includes thousands of species and hybrids, such as cane, rhizomatous, and tuberous types, and nearly all stem cuttings readily develop roots when submerged. Water propagation is appealing due to its simplicity, requiring minimal supplies, and allowing visual confirmation as roots emerge. This technique is a straightforward way to increase your plant collection.
Preparing Begonia Cuttings for Water
Preparing the cutting helps ensure the successful initiation of new roots. For most begonias, including cane types like Angel Wing begonias, a stem cutting is the most reliable choice. Use sterilized shears or a razor blade to make a clean cut just below a node—the point on the stem where a leaf or bud emerges. The node contains the concentrated cells necessary for root development.
The cutting should have at least one or two nodes submerged in the water. Include two to three leaves at the top to facilitate photosynthesis and provide energy for growth. Carefully remove any leaves that would be underwater to prevent rotting, which introduces bacteria or fungus that can compromise the stem. For rhizomatous types, such as Rex begonias, a stem cutting is effective, but a leaf with a petiole attached can also be rooted. Use a clean, small container, like a narrow glass jar, as the smaller water volume helps concentrate the natural rooting hormones released by the cutting.
Monitoring Root Development in Water
Once the prepared cutting is placed in the water, provide the correct environment to encourage healthy root growth. Place the container in a location that receives bright, indirect light. Direct, intense sunlight can cause the water to overheat and burn the stem. A consistent, warm temperature, generally between 65 to 75 degrees Fahrenheit, is beneficial as it mimics conditions conducive to active plant growth.
The water requires regular maintenance to ensure the cutting remains healthy and rot-free. Change the water every few days, or at least weekly, to replenish oxygen levels and remove bacterial buildup or decomposing matter. When changing the water, use the force of the faucet spray to aerate the fresh water before placing the cutting back, as oxygen is required for new root cells to respire. Visible root development typically begins within two to four weeks, with tiny white or translucent roots emerging directly from the submerged nodes.
Successful Transplanting After Rooting
The final and most sensitive stage of water propagation is the transition from the aquatic environment to a soil medium. Roots developed in water are typically more fragile and less adapted to extracting nutrients and water from soil than those grown in a potting mix. To minimize transplant shock, allow the cutting to develop a substantial root system, usually when the roots are about one to two inches long.
Pot the newly rooted begonia into a small container using a well-draining, moisture-retentive potting mix, such as a blend of peat moss, perlite, and potting soil. The cutting is vulnerable immediately after planting, so “harden off” the plant by keeping the soil slightly wetter than usual for the first few weeks. Gradually allow the soil to dry out more between waterings. Maintaining high humidity, perhaps by placing a clear plastic bag loosely over the pot, will further ease the adjustment to the new substrate.