If you've got tight clay soil, break it up good and put your soil or a bag of compost in it and work it in real good. A tablespoon of Osmocote and a sprinkle of bone meal mixed in the bottom of the planting hole works well for me. Don't know if I'd put the rocks in. Depends on what kind of soil you have...

MG organic soil is very good. (I have checked a torn bag at HD, @ $8 per 2 cu-ft ?). It should improve just about any soil. It should fluff up the soil for peppers. To get a better effect I would just mix it with the soil in/around the planting holes. I wouldn't add any rocks to garden soil. It is used mostly for indoor plants, consisting about 1/3 of the mixture.