Grafting crepe myrtles, also spelled crape myrtles, is a difficult and often unnecessary process. However, for the determined gardener who longs for one of the showy, multi-colored shrubs that only custom grafting can obtain, it is not impossible. Unlike many other plants and trees that can successfully support grafts in higher locations, crepe myrtles must be grafted quite low. This means that you will need the patience to allow your crepe myrtle time to evidence whether or not your grafting has been successful.
Perform your graft once spring has arrived in your area. Do not wait until the weather has become hot, since your crepe myrtle will be loath to spare any extra water for a graft.
Select a twig from the variety of crepe myrtle that you wish to graft onto your primary shrub; this is called the scion. Choose a scion that is no thicker than a pencil and appears healthy with no spots or damaged areas. Slice the scion off at the base with a grafting knife.
Shape the cut end of the scion so that it angles 45 degrees and is pointed, using the grafting knife. Gently scrape the bark away from approximately the lower 2 inches of the scion. Wrap this bare end in dampened paper towels.
Examine the low growth of the base shrub for a branch that is healthy and sturdy but not so thick that it cannot be cut easily. Cut the branch off horizontally about 2 inches from where it joins the rest of the shrub. Make a narrow slice laterally into the remaining stub, called the stock, using a wood chisel and a hammer.
Unwrap the paper towels from the prepared scion. Insert the angled end of the scion into the chiseled slice in the stock. Carefully work the scion in as deeply as you can, maintaining as much surface contact between the stock and the scion as possible.
Wrap the entire area, now officially called a graft, in grafting tape. Begin approximately 1 inch above the graft and stop about 1 inch below the graft. Wrap the tape so that each layer slightly overlaps the last.
Cover the tape evenly and generously with grafting wax. The tape will keep out pests and disease, but only the wax can keep out water that would ruin your graft. Repeat Steps 2 to 6 for any additional grafts that you desire.