...I googled it for you....(http://pubs.caes.uga.edu/caespubs/pubcd/L331.htm)Crape myrtle is easily propagated from semi-hardwood cuttings taken during the growing season. June, July and August are excellent times to root cuttings. Take cuttings from new growth of the season, leaving three to four nodes per cutting and several leaves. Rooting hormone is generally not necessary, and cuttings should root in three to four weeks. Place cuttings in a well-drained rooting medium in a shaded area and keep them moist by enclosing them in a clear plastic bag. Cuttings also can be placed in prepared outdoor rooting beds. Thoroughly cultivate the soil to a depth of 10 to 12 inches. Add 4 to 5 inches of organic matter such as peat moss, leaf mold or pine bark to the surface and thoroughly mix it into the soil.Place the cuttings approximately 6 inches apart. Insert them one-half their length into the soil. Mulch with 2 to 3 inches of pine straw, leaf mold or pine bark to conserve moisture. Keep them moist with regular misting.The young rooted plants can be transplanted to their permanent location during the fall and winter.