If you grow lilacs in your garden and are interested in creating a new plant, you can take cuttings and root them to start anew. Keep in mind that lilacs will thrive and grow for as long as a century, so make sure you have adequate room for new plants. If you are planning on growing more lilacs from cuttings of your already existing healthy plants, you will first have to know the proper way to root them.
Take your lilac cuttings and set them aside for the time being. Locate a good pot that is four inches wide and fill it with a soil mixture that includes sand, peat and vermiculite. Make the sand somewhat moist but not exactly wet, and create holes that are evenly spaced in the dirt. These holes will be where your cuttings will be planted.
Cut a piece of a plastic soda two liter bottle from its top to use as a miniature greenhouse roof that will be placed on top of the pot containing the cuttings. Remove the leaves from the bottoms of your lilac cuttings and dip them into a rooting compound. Next, slip each of these into the holes you created in the soil in the pot.
Cover up your lilac plant cuttings with the plastic bottle piece. Make sure to adjust it so that it is upside down, and the spout is slightly buried into the soil mixture to keep it in place. You should then place the pot in a windowsill in a room where it will receive a good amount of sunlight and warmth. This should be left in place for between eight and 12 weeks. You can expect the cuttings to gradually form roots in the soil during this time.
After the 12 weeks are up, you can transplant your cuttings once you see new growth emerging. Make sure to fill the bottom of the new pots with pea gravel before you apply the soil for transplantation.