Seek out nongrafted lilacs grown on their own rootstock; it prevents undesired "suckering" when pruned.

Be diligent about deadheading them, right after the blossoms fade. Cutting them for the house accomplishes the same purpose; just remember to cut above a bud, to stimulate growth. Some experts advise pruning only one-third of the blooms every year, since it takes three years for a new lilac stem to produce flowers. But Mr. Chojnicki says that in Pittsburgh's cooler climate, lilacs bloom on 1-year-old wood, so the more lilacs you cut, the more blooms you'll get next year. Experiment for yourself, but remember not to wait: The Fourth of July is too late, because next year's buds will have already set.

Lilacs have a relatively short vase life that can be extended with proper hydration. After cutting, submerge the entire lilac branch in a large pan of lukewarm water (Mr. Chojnicki uses his bathtub) for an hour. Mr. Chojnicki doesn't pound the stems, as some do; he uses an electric wire stripper to peel off the cambium, or woody bark, which allows the plant to absorb more water. Others claim that smashing the stems injures the plant's water transport structure and, instead, suggest cutting 2 to 3 inches off of the stems. Some lilac lovers swear by Clorox bleach or pennies to keep the water fresh; Mr. Chojnick just changes the water every day.

Source: Paul Benduk Chojnicki