Answer: Yes, syringa vulgaruis can take up to 7 years to bloom so don't give up on yours just yet. They flower best in full sunshine and need a pronounced winter chill to perform. Since lilacs bloom on new growth, prune all of your lilacs back when your French lilac has finished blooming. This will give them all a chance to produce new growth and then develop flower buds for next year's floral display. Even if your old fashioned and pink lilacs do not develop flower buds they will at least have lots of healthy new growth which will help them increase their roots, which will give each plant more energy for flowering once they are mature enough to flower.
Good luck with your lilacs!
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