I was going to grow a bunch of hydroponic greens (spinach, lettuces) and donate them to the local food bank in the Seattle area. It would have been 284 plants at a time. I talked to them about it and they said they couldn't take it because they couldn't store it. I was like, it's hydroponic and I can just cut it on the days you distribute and that would work. They still refused and only wanted to give out dry and canned food. I was disgusted.
I don’t think you should fault the food bank. They have limited space, labor, and money.
You were asking them to take on a labor and space intensive project they didn’t ask for, that might require additional food production safety training to maintain legal compliance. Do they have enough fridge space? Do they have access to a commissary kitchen to process it? Do their customers want it?
If you offered them ready to distribute bags of veg from your plants I’m guessing they might take it.
Charities often run into this problem of someone offering something they didn’t ask for or need, and having to deal with it.
Externally it can seem like an obvious thing: of course the food bank wants greens!
Internally it looks more like: this guy wants to give us an indeterminate amount of his garden veggies, which we might have to process, and aren’t produced in a facility that we can guaranty is safe. we normally only accept donations of dry and canned goods and source our own fresh food for these reasons. Is it worth our time to make an exception?