Question
Can (and how could I) propagate a crepe myrtle from "runners" that are coming up several feet away from the main plant?

Answer
There are actually two methods from which you can choose. The first one is to root the runner right in the soil next to the parent plant. To do this, you bend the runner over and lay it across the soil. Locate the area on the runner closest to the parent plant that can be bent and buried 2-3" deep without breaking the stem. Use a u-shaped pin to hold the runner down at that point. Cover the bent area with soil and it will eventually form roots. Once the roots are established several weeks later, you cut the runner from the parent plant as close to it as possible. You can then transplant the new seedling to a sunny location.

The other method of propagation is from a cutting. Simply cut a tender shoot that is at least six inches long.  Remove the lower sets of leaves. Dip the cutting in a rooting compound. You can purchase this product at any garden center. Stick the cutting one inch into a good potting mix. Be sure to thoroughly wet the soil prior to planting.

Finally, cover the pot with a clear piece of lightweight plastic. Place the pot in indirect sunlight on an east window sill or under fluorescent lighting. After two weeks, check to see if the plant has rooted by slightly pulling on the stem. If you feel resistance, remove the plastic covering and be sure to keep the soil moist. The plant should then be treated as any other seedling.

Good luck, and please write again if I can ever be of assistance.

Regards,

Mike