Lilac bushes generally have a moderate growth rate, typically growing about 1 to 2 feet (12 to 24 inches) per year under good conditions such as full sun, well-drained fertile soil, and adequate water

. Some sources mention growth closer to 30-60 cm (about 1 to 2 feet) annually

. Dwarf varieties may grow more slowly, while common lilacs can reach mature heights of 8 to 15 feet within several years

. Optimal growth occurs when lilacs receive at least 6 hours of direct sunlight daily and are planted in soil with a pH between 6.0 and 7.0

. Proper planting, watering, mulching, and occasional fertilizing can help maintain this growth rate

. In summary, expect lilac bushes to grow approximately 1 to 2 feet per year, reaching full size in several years depending on the variety and growing conditions.