how do u know if ur dirt is good for growing. i have dirt from a grass compost and i have store bought miracle grow. i want to mix them together because im running low on money and miracle grow dirt would this work or would it cause problems?
that would be a good idea, miracle grow alone can be too strong for seedlings as it is mostly peat moss(completely inert) and slow release ferts. the peat will help with airation and water retention of your origanal soil and a little ferts mixed in won't hurt much either, the dirt should dilute it plenty, go for it!
why well composted? i like to use leaves, but grass is good too, it adds an airyness to the soil that helps the roots grow, and overtime breaks down for your plant to eat, my usual is about half composted, like over the winter, don't know if it really helps or not but thats what ive always done.
You can buy a soil test kit at most garden stores that will let you know how good or bad your native soil is....or, you can have it tested by your local agricultural extension office