Is lilac fast growing? Not quite. NC State Extension rates the lilac growth rate as medium, so you shouldn't expect rapid results after planting. Your lilac will add height and spread at a steady pace each year, but it won't fill a space as fast as a butterfly bush or forsythia.
So how fast do lilacs grow in your yard? Once they settle in, most common varieties add 12 to 24 inches of new growth per year. When I first started tracking this on my own bushes, I tied small ribbons on branch tips each spring. The first two years showed slower growth around 10 to 14 inches. By year three, my bushes were pushing 18 to 22 inches per season as the roots took hold.
Your choice of variety changes how fast you reach full size. A standard common lilac takes about 5 to 7 years to hit its mature height of 8 to 16 feet. Dwarf types like Miss Kim get to their full 4 to 9 feet a bit faster. The Japanese tree lilac grows much taller at 20 to 30 feet, but it takes a decade or more to get there.
You can help your lilac grow at its best by giving it the right conditions. Full sun of 6 or more hours each day drives the strongest growth. Well-drained soil with a neutral pH lets roots spread without any problems. In my experience, a light top-dress of compost every other spring gives your bushes a gentle boost without forcing weak growth.
Don't try to speed things up with heavy fertilizer. Too much nitrogen creates fast but weak, floppy growth that can't hold up heavy flower clusters. Your lilac does better with steady conditions than with forced growth spurts. The branches that grow at a natural pace build stronger wood for better blooms.
Patience pays off with your lilac more than almost any other garden shrub. A medium growth rate means your plant builds solid structure year by year. Once a lilac hits full size, it can live and bloom for 50 years or more with very little care from you. That steady growth is what gives these plants their staying power in gardens across the country.
Here's what you should expect year by year with a new lilac. Year one gives you root growth and a few inches of new stems. Year two brings stronger top growth of 12 to 18 inches and maybe a few small flower buds. By year three, your bush hits its stride with full annual growth and your first real bloom display. From year four onward, you get bigger blooms and thicker branches each spring.
Read the full article: Lilac Bush Care and Growing Guide
