25 Common Lilac Tree Seeds Fragrant Flowers Perennial Landscaping Syringa Common lilac bushes ( Syringa vulgaris ) are deciduous shrubs that bloom in the springtime. They are part of the olive family, along with other such ornamental plants as Ash Trees , Forsythia Bushes , and Private Hedges . The outstanding quality of many lilac varieties is the sweet fragrances of their flowers. The blooms appear in branching clusters or panicles. Each flower is only about 1 inch across. The leaves are gray-green to blue-green in color and reach around 2 to 5 inches long; they do not change color in the fall. And the bark of this shrub is gray to grayish brown. The best time to plant lilac bushes is in the early fall before the ground freezes. They have a moderate growth rate of 1 to 2 feet per year. The heavily-scented purple flowers on the common lilac (Syringa vulgaris) bloom in late May and attract hummingbirds, butterflies, and other pollinators. The cut flowers are perfect to bring the scent of spring right into your home. Lilac Germination: 1) Soak the lilac seeds in a shallow bowl full of tap water for one full day to soften the hull and hydrate the embryo. Drain the seeds on a sheet of paper for five to 10 minutes the following day. 2) Stratify in moist perlite for 2 months around 40-45 degrees in the fridge. Mist to keep moist. Do not let them dry. 3) Use a propagation mat to keep the temperature set to 70 degrees. 4) Sow the seeds 1" deep in seed starting mix. Keep moist and do not let dry. 5) Watch for the first sprouts in approximately one month. Leave the propagation mat in place for two more weeks, then remove it.