1. Cut when the flowers on a lilac panicle (the entire cluster of flowers) are one-quarter to one-half open.
2. Use your pruners to split the stem a couple of inches up the center. Crushing the stem with a hammer is an old wives' tale. It doesn't help the lilac take up water.
3. Don't put the flowers in a vase immediately. Instead, remove all the foliage and put them in cool water right up to the neck of the flower. Let them rest and begin taking up water for a few hours or overnight before using in arrangements.
4. When arranging, use a fairly deep vase or container filled with cool water. Keep the flowers out of direct sunlight. Even with care, lilacs are a short-lived cut flower—five days at most, says Lynn. So enjoy all that beauty while you can!