Yes fleece has helped onions this year.
And they should be greening up now, even without fleece.
Mark your efforts are exemplary yet I am afraid there is some aminopyralid herbicide in that manure, for your peas to be almost dead and the onions not much better.
Its a rotten situation because everybody knows that this particular herbicide has lethal persistence, and any farmer buying it has to sign a statement that he/she won’t sell any treated produce off the farm.
Yet there are more and more stories coming out like this.
Veg families that are affected worst are legumes (e.g. your peas) and solanums, to a lesser extent I think are alliums and lettuce family (endive, asters). However your lettuce look ok, even good, so I can’t be totally sure. Potatoes would suffer, if they emerge with curling leaves that would confirm it, have you planted any?
