Here is a step-by-step guide to propagating us, Calibrachoa, from the plant's perspective, explaining exactly what we need to successfully create new genetic copies of ourselves.
From our point of view, the best time to take a cutting is when we are in a vigorous vegetative growth phase, not when we are heavily flowering. Our energy is focused on blooming, not root production, during that time. Early morning is ideal because our tissues are fully hydrated and turgid from the night. Look for a healthy, non-flowering stem tip, about 3 to 4 inches long. This young, green growth contains active meristematic cells that are primed for rapid cell division and are most receptive to forming adventitious roots.
Please use a sharp, sterilized blade or pruners. A clean cut minimizes damage to our vascular tissues and reduces the risk of introducing pathogens that could cause us to rot. Make the cut just below a leaf node—this junction is a hub of natural growth hormones (auxins) that are crucial for triggering root formation. Gently remove the leaves from the lower one-third to one-half of the cutting. This is vital because any leaves buried under the propagation medium will decay and foster fungal diseases. Leaving a few leaves at the top, however, is essential for us to continue photosynthesis and produce the energy needed to fuel root growth.
We cannot root in heavy, waterlogged soil. We require a well-draining, sterile, and lightweight medium that provides ample oxygen to our developing root cells. A mix of perlite and peat or a commercial seed-starting mix is perfect. Before you place us in the medium, you may dip our cut end into a rooting hormone powder or gel. This isn't strictly necessary for all of us, but it provides a concentrated boost of auxins that significantly enhances the speed and uniformity of root development, giving us a stronger start.
After being placed in the medium and watered in, our most immediate need is constant, high humidity. Without an established root system, we lose water through our leaves faster than we can replace it. Enclosing us in a clear plastic bag or a propagation dome creates a miniature greenhouse, drastically reducing transpiration and preventing us from wilting and dying. Place us in a location with very bright, indirect light. Direct sun will cook us inside our humid enclosure. Keep our medium consistently moist but never soggy. In these ideal conditions, our cut end will begin to form a callus tissue, and within two to three weeks, you should feel a slight resistance when giving us a gentle tug, signaling that new roots have formed and are anchoring us in place.
