Successfully starting plants from leaf cuttings is an easy way to experience one of nature's miracles, totipotency. Totipotency is the ability of each and every plant cell to regenerate an entirely new plant. Leaf cuttings can be made from the leaf blade and petiole, leaf blade alone, or sections of the leaf. Many houseplants such as rex and rhizomatous begonias, African violets, streptocarpus, gloxinias and sansevierias are willing candidates.
To start a plant from leaf sections, select a shallow pan to hold the cuttings. A sweater box with a transparent lid works well. Wash it thoroughly with diluted bleach and allow it to dry. Fill the box with 3 to 4 inches of moist, gritty builder's sand.
Water the donor plant well the day before removing the leaf. Using a sharp knife or razor, cut off a mature, healthy leaf from the plant. Young leaves wilt too easily and old leaves do not root well. Lay the leaf on a flat cutting surface. Cut the petiole (leaf stalk) from the base of the leaf and slice the leaf into wedges. Each wedge should have a vein in the center and a piece of sinus (the place where the leaf and leaf stalk meet) at its tip. A rex begonia leaf usually produces 5 wedges. Dip the sinus end of the leaf into rooting hormone and tap off the excess. Sink the wedge into the sand so that a third of the leaf is buried. The remainder of the leaf should stand upright. Line the wedges up so there is at least an inch between them from all directions. An alternative to slicing the leaf into wedges is make a cut in the leaf across each vein and then pin the leaf to the sand using thin wire or bobby pins. Water lightly and cover the box. Place the box in an area that receives bright indirect light or about a foot away from grow lights. Maintain temperatures of about 65 degrees. Check the box regularly and water when the surface of the sand becomes dry. New plants will emerge from the cut areas in a few weeks.
For several weeks little progress will be evident. Roots will begin to grow from the wedge's tip. In about 2 months, small leaves will begin to emerge from the sand if the leaf cutting was successful. If unsuccessful, the wedge will rot after only a few weeks. Remove the new plants from the sand when the leaves are about the size of your thumbnail. Gently shake the sand from the roots and remove the original leaf fragment if it hasn't already rotted away. If leaves have been pinned, carefully cut away the old leaf portions from the new plant. Pot each plant in a 2 1/2 inch container using a well-drained potting medium. Keep the new plants out of direct sun for a few days to acclimate, then move them to a sunny east or west window. Keep the humidity high around the plants by placing the pots on a tray of pebbles and water or running a humidifier. Water plants thoroughly when the surface of the soil begins to dry. As the roots fill their current containers, repot into the next larger pot size. Before long you'll have a normal sized plant to enjoy.
Leaf cuttings can be taken at any time of the year. The process is a slow one, but very rewarding.
This article originally appeared in the June 16, 1995 issue, p. 88.