Wow, avoiding the addition of phosphorus definitely limits your ability to fertilize with a commercial product, doesn't it! We have phosphorus naturally in the soil here, but its not usually enough to cause problems. But the specially formulated "Tomato Fertilizer" products seem to always have a high middle number in the analysis. If you're using the Ironite Mineral Supplement, it's a really low analysis at 1 - 0 - 1 ! Might need to supplement it, maybe ammonium sulphate (cheap lawn fert is usually this) would help keep the plants going.
Another nutrient that's cheap and easy to apply by itself is magnesium. Ironite has a magnesium component but it is a trace amount. I'd try a teaspoon or two of Epsom Salts in a gallon of water on some of your plants and see what it does. Can't hurt. It's made a world of difference to my brugmansias and orchids, and I'm trying it on my tomatoes in my Earth Boxes. They seem to like it so far after one dose.
If you can come by some compost tea, (pure vegetable material, no manure in it) that also might be a good supplement that's low in phosphorus.
