From the time their colors first appear, garden lilacs (Syringa spp.) put on one of spring's longest shows. A single bush may fill your garden with flowers and scent for nearly three weeks, but cut those blossoms for bouquets and the countdown begins. The time to enjoy their beauty and fragrance is short. Extending your bouquet's potential starts with healthy garden lilacs and bloom-prolonging care.
For an abundant supply of cut blooms, make sure lilac bushes get at least six to eight hours of direct sun each day. The more sun, the more flowers. Well-drained soil with pH near 6.0 to 7.0 is best. Lilacs hate wet roots, but lush blossoms require regular water. If it hasn't rained, give the lilacs 1 inch of water per week. Give lilac bushes excellent air circulation, and mulch your shrubs to prevent weeds and maintain soil moisture and temperature. Established lilacs generally don't need fertilizer. Using high-nitrogen lawn fertilizers nearby promotes leafy growth at the expense of blooms.
Cut lilacs rarely last more than five days. To extend your enjoyment, cut stems in evening and choose panicles one-fourth to one-half open. Use sharp bypass pruners to cut sharp angles, then split the stems up the center with a 2-inch cut. Remove the leaves, and place the lilacs up to their necks in a deep bucket of cool water. Let them soak several hours or overnight. For arrangements, use a deep vase, cool water and floral preservative. Make your own by adding 1 crushed aspirin, 1 teaspoon vinegar and 1 tablespoon sugar to 3 cups of lukewarm water. Change the water and recut the stems daily, and keep the bouquet out of direct sun.
Pruning for Bountiful Blossoms
For prolific lilac blooms from year to year, proper pruning is essential. When the bushes finish blooming, remove the spent blooms. Left to set seed, they reduce future flowers. Consider your cut stems part of this annual rite. Prune stems back to a set of leaves, using bypass pruners. Lilacs set their spring flower buds during the previous summer, so prune immediately after they bloom. You'll sacrifice next year's blossoms if you delay. Rejuvenate neglected lilacs by removing one-third of the plant each year for three years. Cut the oldest stems to the ground using bypass loppers or a pruning saw. Always sterilize your pruning implements with household disinfectant before and after each bush, whether harvesting flowers or pruning.
Choosing Cut-Stem Cultivars
Lilac blooms depend on winter chill, so choose varieties suited to your climate. Lilacs were limited to U.S. Department of Agriculture plant hardiness zones 2 through 7 for many years, but new varieties thrive through USDA zone 9. Extend your season several weeks by growing species and hybrids with differing bloom times. Old-fashioned, single flowers are fragrant, but double-flowered blossoms last longer on shrubs and indoors. Two popular florist lilacs are "Mount Baker" (Syringa x hyacinthiflora "Mount Baker"), an early-flowering single with pure-white blooms, and Beauty of Moscow (Syringa vulgaris "Krasavitsa Moskvy''), a midseason, blush-pink double. These fragrant lilacs grow in USDA zones 3 through 7.