And what dressing do you recommend and how often?
Sorry for late response. Top dress with the same soil you’re using. It’s just a way of replenishing what the plant used in the soil. Another option is dry amendments, I prefer this option because top dressing with the same soil will require you to remove soil to put fresh soil in. Also, the plants requirements for different NPK ratios change as the plant ages, the NPK ratios in that soil is extremely low, so top dressing with the soil might not be the best option. I also noticed you have your pots on a flat surface. When using smart pots it’s a good idea to keep them elevated, and sitting on something so they can drain from the bottom like a milk crate for example, otherwise the soil will never dry out. I haven’t read any other post so maybe a lot of what I’m saying has already been covered.