Lilac late

Homework question:
Why would a Lilac flower late (assuming an early variety)?

 

Later than it usually does in previous years, or later than you expected that cultivar to do so?

 

This is homework for Master Gardeners course. Clinic questions. The question says we had a cold rainy spring. My question asks to clarify if it would normally be an early bloomer. Assuming yes... is it cold or cloud or a combination that would delay blooms? Or am I missing something?

 

I don't know the answer specifically for lilac, and Douglas Justice doesn't mention lilac in his January 2018 in the Garden | UBC Botanical Garden blog article, but he does have a paragraph on flowering and weather and how that has varying effects on plants.

 

Thank you for the reference. Exactly what I was looking for. The internet is full of info but my teacher is looking for credible references. :)

 

I think your answer will be on this page:

Common Purple Lilac |