I have three indoor plants that I haven’t fed for over a year, since I repotted them. They have some yellow leaves and aren’t looking as healthy as they could. I am going to start feeding them with a liquid plant food. The instructions say to use 7 drops for 1 qt (approx 1 L) of water. If I do this, will it take quite a while to build nitrogen levels in the soil before they recover, or will they start looking good quickly? Is there any advantage if I increase the concentration? Is there any advantage if I run lots of food-laden water through them, rather than just filling until it can’t take any more?
I usually water them once a week by watering them until water runs freely out the bottom. This has kept the plants in a pretty good state for around four years, apart from this yellowing.