Q.Vitex Has Very Small Leaves
My 3 year old Chaste Tree has clumps of tiny, underdeveloped leaves among some regular sized leaves. No flowers really, as those are undersized as well.. She’s located in full sun, and watered twice a month during Phoenix AZ summer heat. The same happened last year. What could be the problem? What’s missing that causes such small, flower-less growth?

Certified GKH Gardening Expert
Unfortunately, your photo did not come through. I am unable to see the damage. Sometimes, too much nutrients can cause these types of issues, but so can virus and diseases.
The trees require pruning, quite frequently. This can help regenerate a slow tree.
In the meantime, this article will help you to understand the care that these trees require:
https://www.gardeningknowhow.com/ornamental/trees/chaste-tree/chaste-tree-cultivation.htm