Propagating a lilac tree from a shoot, or cutting, depends on a small window of opportunity. Shoots should be removed from the mother plant immediately after the blooms have died back. Lilac trees take up to two years or more before they produce their first flowers, and cutting should not be taken before this time. Once established, the new lilac tree will take the same amount of time to flower.
Cut new growth shoots from the lilac tree that are 4 to 8 inches in length. These shoots are growth that continues after the lilac tree has bloomed.
Dip the cut end of the shoot into water and then immediately into rooting hormone. The lower inch of the cutting should be covered with the rooting hormone powder.
Fill 6-inch growing pots with sand. Water the sand until water drains from the bottom of the pot.
Use a pencil or chopstick to create a hole 2 to 3 inches deep in the sand.
Place the lilac shoot into the hole and press the moist sand around the cutting to keep it upright in the pot.
Keep the sand and the cutting moist to the touch at all times. Lilacs prefer high humidity so moisture for the cutting is imperative.