I feed every watering. But, my soil is very light. It's more accurately called "soiled soilless." It's just enough to be a soil. But, I don't count on it being rich and supplying the plant very much. I pour in Grow More - Sea Grow (a powerded, inexpensive soil fertiizer with a organic-based leaning. The soil's just soiley enough to facilitate that level of organic fertilization. I don't know. It works though. And, the plants seem to like it better each feeding (probably because the soil isn't rich).