I planted several cherry tomato plants in very large tubs
(6+ gallons) with proper drainage holes, a pea-gravel base,
topsoil, 2 weeks ago. They have blossoms on them.
Three of them suddenly have a lot of yellowing leaves.
It has been cool here, in the 50's & very rainy with
very little sun. It is normally in the 70's & high 80's
by this time.

Any ideas on why these tomatoes are turning yellow?
I am in northern VA.

Input appreciated.

Minteeleaf