Crepe myrtle (Lagerstroemia) is a popular, brightly flowering shrub or small tree grown in warmer climates, celebrated for its long-lasting summer blooms and attractive bark. Propagating this plant means creating new, genetically identical plants from small pieces of the parent, typically using stem cuttings. Successful propagation hinges on precise timing, as the physiological state of the cutting—soft, new growth or hard, mature wood—dictates the rooting method. Understanding when to take the cutting is the most important factor in ensuring the new plant develops a healthy root system.
Understanding Seasonal Timing for Cuttings
The best time to propagate crepe myrtle falls into two distinct windows, corresponding to different stages of the plant’s annual growth cycle: active growth (softwood) or dormancy (hardwood). The choice of timing influences the technique, the environment, and the ultimate success rate.
Softwood cuttings are taken when the plant is fully active, utilizing the stem’s high moisture content to quickly initiate roots. This method requires supplemental humidity and a specific rooting medium to prevent the cutting from drying out.
Hardwood cuttings are collected during winter dormancy when the plant has stored maximum energy reserves in its woody tissues. These reserves fuel a slower, more resilient rooting process once warmer conditions arrive. The growing season is ideal for the faster softwood method, while the dormant season is reserved for the slower hardwood technique.
Softwood Propagation During Active Growth
The optimal window for taking softwood cuttings is during late spring and early summer (May through July), when new growth is pliable and green. Cuttings should be taken from the tips of the current season’s growth, measuring four to six inches in length with several leaf nodes. Making the cut just below a node provides the best site for root emergence.
After collection, remove the leaves on the lower two-thirds of the cutting to minimize water loss. Dip the freshly cut end into a rooting hormone, which stimulates root development. Insert the prepared cuttings into a sterile, well-draining rooting medium, such as perlite and peat moss or coarse sand.
Maintaining high humidity is necessary, as softwood cuttings lack the woody structure to regulate water loss. Create this environment by placing the container under a clear plastic dome or inside a plastic bag, keeping the medium consistently moist. Place the cuttings in a warm location that receives bright, indirect light, as intense sun can scorch the foliage. Roots generally begin to form within four to eight weeks.
Hardwood Propagation During Dormancy
Hardwood cuttings are taken during the tree’s dormant period, usually between late November and early March, before new spring buds appear. This technique capitalizes on the plant’s stored carbohydrates, making the resulting young plants resilient. Selected cuttings should be mature, pencil-thick, woody stems from the previous season’s growth.
Cuttings should be six to twelve inches long; cut the top end at a slant and the bottom end straight to distinguish orientation. Applying a rooting hormone to the base can improve the success rate. These dormant cuttings are then planted directly into an outdoor rooting bed or potted in a container filled with a well-draining medium like sand or perlite.
When planting outside, insert the cuttings deep into the soil, leaving only the top one or two inches exposed. In colder areas, cuttings may be bundled for cold stratification in moist sand or sawdust until spring temperatures warm up. This cold exposure helps break dormancy and primes the cutting for active growth. Rooting occurs slowly over the winter, with new foliage emerging in the spring.
Essential Care After Rooting and Transplanting
Once the cuttings have successfully rooted, a tug test will reveal resistance, indicating a secure root ball. The young plants must then undergo “hardening off,” which acclimates them to lower humidity and harsher outdoor conditions. This involves gradually increasing their exposure time to open air over one to two weeks.
After hardening off, the rooted cuttings can be transferred to individual one-gallon containers filled with a standard, well-draining potting mix. The best time to transplant the young crepe myrtles into their final garden location is typically the following spring, allowing the roots a full season to establish themselves in the container.
Initial care involves placing the young plant in full sun to partial shade, ensuring the soil is kept consistently moist but never waterlogged during the first few months. Apply a light, diluted liquid fertilizer monthly during the growing season to support robust development. Apply mulch around the base to conserve moisture, keeping it away from the trunk to prevent rot.