Lilacs are one of the most pleasant bushes of spring. They're not only beautiful with their clusters of colorful blooms, but their fragrance is a hallmark of the season. If you already have a lilac bush in your yard, dividing it to create new, smaller bushes is an economical way to multiply and make use of what you already have.
Know the type of division. For the softwood lilac bush, the best type of division is layering--nicking and bending a young, green branch into a small trench, then burying the branch to allow it to form roots.
Choose a lilac branch to layer. Look for a low-hanging branch in early spring and choose a dormant or one-year-old branch. The branch should be flexible and needs to bend easily for layering.
Dig a small hole or trench 3 to 4 inches deep. You will need to leave about 12 inches at the tip of the branch sticking out of the hole, bent upward, so locate the hole appropriately.
Bend the branch into the hole. The branch needs to bend downward into the trench then back up. Place a small stake next to the hole to help form the branch. The branch tip can be tied to this stake with string or an old pantyhose leg to help it form and shape correctly.
Use a knife to nick the branch where it rests in the hole and bends back upward. Put a small amount of rooting compound on this open cut to help the branch form roots.
Bury the bend in the hole after it has been nicked and covered with rooting compound. If the branch tries to pop out, use a wire wicket or landscape staple to hold it in place down in the hole. Cover the bend with dirt.
Mulch with straw, sawdust or even leaves and keep the layered branch moist at all times.
Cut the branch away from the parent bush after it has had a season to form new roots. You should cut the branch where it goes into the ground. Do not disturb the newly formed roots. Allow two to three weeks after cutting before digging up the new plant. This new lilac bush can be moved to a temporary location or a pot for tending before moving to a permanent location.