- Name: French Lilac - Other Common Names: Old Fashioned Lilac / Common Lilac - Scientific Name: Syringa Vulgaris - Color: Lilac 4 - 8" Long Flower Heads - Plant Seeds: Outdoors After Frost / Indoors Weeks Before Last Frost - Bloom Time: Spring - Early Summer - Hardiness Zone: 3 - 7 - Plant Height: 10 - 15' - Plant Spacing: 6 - 12' - Light Requirements: Sun - Soil & Water Preferences: Average - Quantity: 25 Seeds - Other: Lilacs Are Very Fragrant! It Is One Of The Most Popular Scents World Wide. Lilacs Can Be Pruned To Form A Small Shrub Or A Tree. They Also Make Excellent Bonsai Trees.