What you need first is healthy soil and good biological activity in that soil. If you start by doing the bed preparation
, use soil amendments (lava sand, greensand, decomposed granite, etc.) and dry molasses along with compost tea, then applying beneficial nematodes
, you'll have a good start. If you have a soil test
done you'll know if there is something missing and need to add to it.
Egg shells, coffee grounds, lots of things can go into the garden. If you have down limbs and branches or trees on or near your property, getting wood chips from those local trees is the best mulch.
If your yard or garden area hasn't had any cultivation activity for a while (i.e., is just a grassy area) then it is probably good to go, unless you're in a particular soil type that needs a boost. If it has excess amounts of harmful chemicals, then you would need to detox. I'd suggest that unless you have a reason to believe the latter, that you proceed with amending the soil and see what grows.