Question
I would like to know if and how to root a lilac branch-have received two different colors and would like to grow them both

Answer
Hi Barbara,
Thanx for your question.  If the branches are woody there's a good chance these will not root.  For best results, take softwood (green) cuttings in the spring.  Make cuttings that don't have flowers.  Cuttings should be about 6 inches long.  Strip off all but the end two leaves.  Dip the cutting in rooting hormone.  Stick the cutting into warm, wet sand and keep the bottom warm.  Keep the cuttings sealed inside a clear, plastic baggie.  Keep at about 75F.  Rooting should have taken place in 8 weeks but complete rooting will take longer.  If you don't seal the cuttings in a plastic bag you must mist the cuttings several times a day to keep them from drying out.  I hope this helps.
Tom