Black locust trees include numerous cultivars, such as Lace Lady, which goes by the botanical name of Robinia pseudoacacia. Twisty baby black locust is the common name for this ornamental variety of locust tree. This dwarf tree grows about 15 feet tall and produces twisted green foliage on curvy branches. Although locust trees produce flowers, male and female blossoms grow on separate trees and harvested seeds from hybrid varieties seldom grow true to form. Propagating these trees from stem cuttings provides an easy, inexpensive method of obtaining new trees that resemble the parent plant.
Harvest the cuttings from a healthy twisty locust during the dormant season, preferably in late fall or early winter. Select branches that include numerous leaf nodes evenly spaced along the lengths. Use a sharp knife to slice off branches slightly below the area where the soft growth meets hardwood. Determine this by gently bending the branches. The hardwood feels firm and resists bending.
Wrap the cuttings in damp paper towels and place them in a dark plastic bag as soon as you remove them from the tree. This will help reduce stress and protect the cuttings from drying out before you can plant them.
Mix together equal amounts of perlite, peat and coarse sand. Fill the pots with the planting medium. Place the pots on drip trays to catch any excess water. Create a deep narrow hole in the centre of each pot, using a long stick or a wooden dowel. The diameter of the holes should be about equal to the diameter of the locust cuttings.
Lightly wound the bottom half of the cuttings by scraping the edge of your knife along the bark, making a slight scratch along the length of the stem. Dip the cuttings in liquid rooting hormone and press them into the prepared holes in the soil. Gently tamp the soil around the cuttings to hold them in place. Water slowly until a few drops emerge from the drainage holes.
Cover the planted cuttings with a loose layer of cling film to help minimise evaporation. Set the cuttings in an area that receives indirect light. Keep the cuttings indoors throughout the remainder of winter, allowing them sufficient time to produce new roots. Transplant rooted cuttings outdoors in the springtime.
Keep the soil slightly damp while rooting the new cuttings.