Plant cloning, or the propagation of plants by cuttings, produces a new plant that is genetically identical to the mother plant. Cloning produces a large number of new plants from one specimen, helping to maintain the species, rejuvenate an older plant or produce inexpensive new plants to populate the garden. Most herbaceous plants and shrubs readily clone by stem cuttings, while hardwood trees are often more difficult.
Choose a mother plant that is healthy and possesses the desirable characteristics for the new plant. The new plants will be identical to the mother, so choose the best specimen to clone.
Fill a small cup or pot with clean, moist sand or other rooting medium. Punch a hole in the rooting medium with a pencil or small stick. Forming the hole in advance reduces friction when the stem is planted and avoids rubbing off rooting hormone, if used. Also, prepare the rooting hormone, if needed.
Remove the recommended plant part to use as a cutting. Many plants need only a leaf or stem tip with a few leaves attached. Shrubs and trees require a softwood or hardwood cutting. Plant Propagation by Stem Cuttings: Instructions for the Home Gardener from North Carolina State University has a chart on the type cuttings needed.
Use a sharp razor blade or craft knife to take the cutting of herbaceous plants. Pruning shears are best for woody stems. Clean the tools with rubbing alcohol or a dilute bleach solution before use to avoid spreading diseases. Make a clean cut and void bruising or crushing the plant.
Keep the rooting medium moist and provide high humidity until the roots develop. The newly cut stem has no roots and must absorb moisture through the leaves and stem. Mist the plants, cover with plastic or place them next to a humidifier or other source of moisture for best results.
A small tray with a clear plastic dome is commercially available for rooting plants, but a similar setup can be made from a deli takeout container often used for roasted chicken or salads. The top should be domed to allow room for the plants and clear to let in sunlight. Punch a few small holes in the top for ventilation and place the planted cuttings into the container. Check moisture levels in the rooting medium daily, watering as needed. Remove the lid when the roots are established, usually in two to three weeks.