more about my 'system'
I have used vermiculite only on houseplants and when starting seeds indoors. My soil has always been enriched by leaves and manure - and grass as I will tell here.
I sprinkle grass clippings over a freshly planted area and add more each time I mow. I grow sweet corn in rows. It fills the available space when mature. I pile lots of grass - 12" or so - between the rows, pulling it back from the corn plants so it does not touch them. I pull and shred the corn stalks soon after harvest while they are green and till them into the area to prepare for late crops. I tried just tilling in the stalks, but they don't get chopped up enough by the tiller (contrary to the Troy-bilt claims). I try to shred and till in all of the plants as soon as harvest is complete. Green plants and vines break down quickly. Spoiled or damaged vegetables also get shredded and tilled.
I use grass mulch in lesser quantities over all the crops. As soon as any crop sprouts, I start sprinkling grass clippings between the sprouts. I don't put much on at a time, so I let it touch the plant if that is where it lands. It takes a while to build up enough mulch to discourage the weeds.
I did not fill boxes to make my 'raised beds'. I just added lots of stuff - leaves, manure & grass - to my garden which increased the volume of the soil in the garden area. I simply pile up the excess. At first it seems odd to plant the 'sides' of the bed. I suppose that it still does, but less so. Because I don't have a box, grass is constantly encroaching on the garden. This turns out to be OK, because I like to constantly move the beds, which I could not do if they were boxed. When I till in the spring, I enlarge the bed on one side and leave a strip on the other side untilled. A bit of shovel work is required to remove the excess dirt from the untilled area to lower it to lawn level.
I arrived at my method partly because I had equipment - a Troy-bilt tiller and a pickup to haul leaves and manure. I can bring in lots of organic material and work it in without excessive effort. The worms do a great job of 'double-digging' to break up the deep soil and they enrich everything. A large lawn provides plenty of grass clippings for mulch and for composting. I move the compost pile each season, too, so that the soil beneath the compost heap enriched by leached nutrients becomes garden area the next year.
I guess that I have rambled on long enough. Best of luck on developing your own personal system.