Propagation is a simple method of cloning a plant by taking a piece of the parent and encouraging it to grow roots. This form of asexual reproduction is a popular technique for home growers, allowing them to multiply their favorite indoor plants without the expense of buying new ones. The process requires attention to detail at each stage, from preparing the tools to establishing the new plant in its permanent home.
Essential Tools and Preparation
Before making a cut, gathering the necessary supplies and preparing the parent plant is important to ensure a clean and successful propagation. The tools used for the cut must be sharp and sterilized, which prevents the spread of pathogens from other plants to the new, vulnerable cutting. You can sterilize pruning shears or a razor blade by wiping them with 70% isopropyl alcohol or by soaking them in a solution of one part household bleach to nine parts water for a few minutes, followed by a water rinse and thorough drying.
Selecting a healthy, vigorous stem from the parent plant is important. The best time to take a cutting is often during the plant’s active growing season, typically spring or summer, when it has the most energy reserves to dedicate to root growth. Look for new, semi-hardwood growth that is neither too soft nor too woody, as this tissue tends to root most readily. Clean containers, whether for rooting or potting, should also be prepared and ready to receive the cutting immediately after the initial snip.
Locating and Making the Initial Cut
The location of the cut is the most important factor in stem cutting propagation, focusing on a structure known as the node. A node is a slightly swollen area on the stem where a leaf, bud, or branch emerges, and it contains a higher concentration of the meristematic cells necessary for root development. The goal is to maximize the cutting’s ability to generate new roots quickly, as it is a severed piece of tissue with limited resources.
To make the cut, aim to sever the stem about one-quarter to one-half inch below a node, as this ensures the node is included at the base of the cutting, which is where roots will form. A cutting length of three to six inches, which typically includes three to four nodes, is often considered the ideal size for many indoor plants. Making the cut at a slight angle or straight across is less important than ensuring the blade is clean and the cut is swift to minimize damage to the plant’s vascular tissue.
After making the cut, remove any leaves that would be submerged in the rooting medium, as these leaves will rot and introduce disease into the area where new roots are trying to form. Leaving one or two leaves at the top of the cutting is necessary for photosynthesis, which provides the energy needed to fuel root growth. Removing excess foliage minimizes water loss through transpiration, preventing the cutting from drying out before a root system can be established.
Encouraging Root Development
Once the cutting is prepared, the next phase is placing it in a medium that encourages the formation of new roots, typically either water or a specialized potting mix. Water propagation involves placing the node end of the cutting into a clear glass vessel filled with clean water, allowing you to monitor root growth visually. The water should be changed every few days to maintain oxygen levels and prevent the growth of anaerobic bacteria that cause rot.
Direct rooting in a solid medium requires a well-aerated mix, such as a blend of perlite, peat moss, or coarse sand, rather than dense, moisture-retentive potting soil. In this method, the cutting is inserted into the moist medium, and high humidity is maintained, often by covering the pot with a clear plastic bag or dome to reduce water loss. For cuttings that are slower or more difficult to root, the use of a rooting hormone can significantly increase success rates by mimicking the natural auxins that stimulate cell division and root formation.
Rooting hormone, which comes in powder, gel, or liquid form, is applied directly to the cut end of the stem before it is placed in the soil medium. The hormone contains synthetic compounds that encourage the undifferentiated cells at the node to specialize into root cells. If using water propagation, rooting hormone is not recommended because the water washes the substance away, rendering it ineffective and potentially fouling the water.
Establishing the New Plant
The cutting is ready to be moved to a permanent pot when the newly formed roots have reached a sufficient length to support the plant in a soil environment. Transplant when the roots are approximately one to two inches long and have begun to develop small, secondary branches. Waiting for roots much longer than this can make the transition more difficult, as the delicate “water roots” are structurally different from “soil roots” and must adapt to the new medium.
To transplant, fill a small pot with drainage holes, which is only a few inches larger than the root ball, using a standard, well-draining potting mix. Carefully transfer the rooted cutting, being gentle with the fragile new roots, and secure it by filling in the remaining space with soil and lightly tamping it down. Immediately after potting, give the plant a thorough watering to settle the soil around the roots and minimize transplant shock. Keep the soil consistently moist for the first couple of weeks to ease the transition from a water-based environment, and avoid applying fertilizer, as the young roots can be easily burned by a high salt concentration.