Thanks for the responses.
lucR, yes, I think it stood too long at the same spot, it's been almost 2 months, I was planning to move them when replenishing it, but it seems like it must be earlier! I'll remember that. Thanks again!
Thanks leatherback, a fun fact about the Castor Cake is that it's not the best option to spread over the surface, as after a few weeks it makes the top of the soil compacted (only the top, maybe because it's a bit oily), so you'll have to rake the top, to water to flow normally tru' it. I mean, you can do it, but it's easier to control that with bags or little baskets/pots.
And talking about favorable spots, I find it amazing how roots behave.
Charles Darwin in analogy once wrote that the tips of plant roots are like the brains of plants. Roots sense the environment. They sense the water, where there are more nutrients, and they go for these resources. Roots are the "smartest" part of the plant.