The crepe myrtle (Lagerstroemia) is an ornamental shrub or small tree valued for its vibrant summer flowers and attractive bark. Rooting cuttings is a common and effective method of asexual propagation. This technique creates new plants that are genetically identical to the parent, allowing gardeners to expand their collection without the genetic variation that comes from planting seeds. This guide provides a practical approach to successfully rooting your own crepe myrtle from a cutting.
Timing and Selection of Cutting Material
The optimal time to take a cutting depends on the physiological state of the material, which falls into two main categories: softwood or hardwood.
Softwood cuttings are taken from the new, flexible growth of the current season, typically in late spring or early summer (May through July). These cuttings root quickly, often in four to six weeks, but they require high humidity and careful monitoring to prevent wilting.
Hardwood cuttings are taken during the dormant season, usually from late fall through late winter, utilizing stems that have matured and hardened. These woody cuttings are more resilient and less prone to drying out, but they require a longer period, sometimes several months, to develop roots.
Regardless of the type chosen, select material from a healthy, disease-free parent plant. Softwood cuttings should be taken from the green, non-flowering tips of branches, while hardwood cuttings should be taken from mature, pencil-thick stems.
Preparing Crepe Myrtle Cuttings for Rooting
The physical preparation of the cutting significantly influences root development. First, use clean, sharp pruning shears or a knife to take a cutting approximately 4 to 6 inches long. Sterilizing tools prevents the transmission of pathogens to the vulnerable cutting tissue.
Next, carefully remove all leaves from the lower two-thirds of the stem, leaving only a few leaves at the tip for photosynthesis. Removing lower foliage minimizes water loss and prevents leaves from rotting when inserted into the medium. Lightly wound the base of the cutting by scraping a small, half-inch strip of bark on one side. This controlled injury stimulates the formation of callus tissue, from which new roots will emerge.
The base of the cutting should then be dipped into a rooting hormone, which contains synthetic auxins to promote root initiation. Rooting hormone, available in powder or liquid forms, increases the rooting success rate and speed. After dipping, gently tap the cutting to remove excess product, as an overly thick application can inhibit growth.
Establishing the Rooting Environment
The environment must be managed to encourage root growth while preventing dehydration. Choose a suitable rooting medium that holds moisture while providing excellent aeration and drainage. An effective mixture is one part peat moss blended with one part perlite, or a sterile, coarse potting mix. The medium must be pre-moistened before inserting the cuttings.
Use a pencil or similar tool to create a small hole in the medium, avoiding scraping off the rooting hormone during insertion. Place the base of the cutting 1 to 2 inches deep, ensuring the lower leaf nodes are buried. Crepe myrtle cuttings require high humidity to prevent the remaining leaves from drying out.
High humidity can be created by placing a clear plastic bag over the pot, forming a mini-greenhouse, or by using a propagation dome. Place the container in a location that receives bright, indirect light, as direct sun can scorch the cutting. Maintain a consistent warm temperature, ideally between 70 and 80°F, for root development. Roots typically form within four to eight weeks; resistance when gently tugging the cutting indicates successful rooting.
Post-Rooting Care and Transplanting
Once the cutting develops a root system, it must be gradually introduced to normal growing conditions through “hardening off.” The young plant is accustomed to high humidity and would quickly dry out if moved immediately outdoors. Over one to two weeks, incrementally remove the plastic cover for increasing lengths of time daily, slowly acclimating the plant to lower ambient humidity.
After hardening off, move the rooted cutting into a larger container, such as a one-gallon pot, using standard, well-draining potting soil. This intermediate step allows the root system to grow robustly before being subjected to the stresses of the garden. During its first year in the pot, monitor soil moisture consistently, keeping it evenly moist but never waterlogged.
The new plant should remain in the pot for the remainder of the growing season to focus on developing a strong root mass. Planting the young crepe myrtle directly into the ground is best done the following spring, after the final danger of frost has passed. This timing allows the plant an entire growing season to establish itself before facing winter.