Glad to hear they have recovered! I think you mostly answered your own question when you said you put them out earlier than last year.
I recognized your mix as 5:1:1 immediately
It's what I use for my container plants too.
They way I implement my fertilizer in containers is to use a mix of dry such as Tomato Tone (which I mix in when planting because it needs time to break down, be close to the roots, etc) and soluble fertilizers when I water such as Texas Tomato Food, Neptune's Harvest, Dyna Gro.
I know some people say not to fertilze till the plant starts growing, but in my experience the plant starts growing faster when you give it soluble fertilizer when transplanting. That's the way Mom taught me and it works for me. If it were synthetic fert I give at 1/2 strength if transplanting, but organics I usually apply full strength.
I hope you continue posting pictures as the season goes on!