This is no doubt a crazy question but.....
Can you increase the iron available to plants by adding a newly rusted (so the rust rubs off on your hand) nail or screw to your water? I'm thinking specifically about Kratky buckets but it could also be in watering can water for the plants. I've read about people being able to get some iron from using cast iron pans FWIW and I don't have anything like Ironite but I do have a bunch of rusted screws. Just an
idle thought ....
Anne
P.S. Bill, your garden is so beautiful!