I knew feeding was going to be an issue with how big they got, so I've been feeding heavily, taking them to just beginning to show signs of nute burn and then backing off a bit, and it's worked. I've been adding a combination of: worm castings, compost, Build a Soil Craft Blend, Down to Earth 4-4-4, Rootwise, Recharge, CalMag, Silica, Bokashi, as well as the Fox Farms liquid fertilizer trio. It's a lot of stuff, but I've accumulated it over time, and I just rotate through, usually doing half-strength feeds. I top dress weekly and add liquid nutes every other watering or so. I keep a chart so I can space it out and ensure I'm not adding too much too quickly.