Ptrs ...
I am going to share my point of view which is not necessarily backed up by science of rules or anything else except my own version of common sense, which may be pure foolishness. Anyone else, please feel free to contradict me.
It would be wonderful to know where you are gardening, but in this case, I don't think it makes much difference.
What you are talking about is, in principle, the concept of a no till gardening. That's where everything is put on top and is allowed to be decomposed by the elements and worked down into the soil to the feeder roots to the plant for its use as time goes on. In nature, that's exactly how its done. No one goes out and pulls back the mulch / duff and puts down the nutrients ... unnamed ... and covers them back up for the plants. In fact, nature is rather inconsistent about providing the "proper" nutrients" for the plants in the garden we value as we look at her work.
Rule of thumb when we apply fertilizers in a no till garden is to water well before application and after applicatin. I like to apply all fertilizers during the growing season with a light hand often because the high summer temps in my climate seems to eat both mulch and fertilizers quickly. The roses seems to be happy and don't know that I haven't bothered to dig it in.
btw ... I have never used Mills Magic Mix. I may be telling you how to use it all wrong, so please use your own judgement and experience, too.
edit ... typo again ..
