Lilacs are one of the most cherished old fashioned fragrant bushes. They are also one of the earliest flowers to bloom in the spring, spreading their perfumed scent throughout their yards. They will not grow in the southern regions, as they need a cold period of dormant rest. They propagate easily by sending out suckers but you can also use softwood cuttings with great success. The cuttings root so well, you can even attempt to root a cut blossom as long as it has a long enough stem. There are just a few things that it requires to send out new roots.
Take the lilac blossom cutting that you have and look at the cut end. It will need to have a fresh clean cut for successful rooting, so slice a new cut at a 45 degree angle across the bottom of the stem. Set the fresh cut into water until you are ready to root it.
Prune the lilac cutting while it is sitting in the water. Remove any bottom leaves and clip off the blossom. Too much energy will be needed for the cutting to produce roots to also sustain the blossom. Leave whatever leaves are on the top of the cutting.
Dip the cutting into rooting powder and give it a gently tap to remove the excess. This powder will simulate the growth hormones produced by the plant when it needs to produce more roots. Sometimes cuttings are successful without the rooting hormone powder, but it makes it much easier.
Slip the powdered cutting into the container holding the planting medium. It should be filled with a 50:50 mixture of wet peat moss and sand and then have a 3 inch deep hole pressed into it, just wide enough for the cutting. Press the soil in around the stem.
Cover the container and its cutting with a clear plastic bag to form a highly humid atmosphere for the cutting. Place it in a warm but dark area where it stays around 70 to 75 degrees F, for about six to eight weeks. You can tell when roots have formed when you give it a gentle tug and find resistance.
Transplant the the rooted cutting into a plant pot filled with regular potting soil. It will need several more weeks of protected growth before you can plant it outside in a sunny location where it can grow permanently. It likes loamy soil with good drainage. To prevent shock to the plant, bring the new plant outside for just a few hours a day, increasing the time daily until it can withstand being outside all the time.