so according to SFG you need approx 1/3 each of compost, vermiculite and peat moss.
it actually took me some time and math to figure out how that means….
A 4’x4’x6″ frame contains 8 cubic feet, so 1/3 of each would be 2.67 cubic feet of each of peat, vermiculite and compost.
our frame is 4’x8’x6′ so that is 16 cubic feet and 1/3 would be 5.34 cubic feet.
Nikki (our wonderful professional gardening cousin) recommends less vermiculite so we’ll use less than 1/3 and more compost.
we get awesome compost from the town! and Nikki will also give us some great organic fertilizer for later in the season.
also according to SFG you should put down a weed barrier (prepared weed preventing fabric/cloth, newspaper or cardboard) on the grass before filling the frame with soil. according to Nikki – You can use newspaper- black and white only. no color, no glossy pages, or you can use brown cardboard…. do not use a weed barrier you want the worms to come up through into your bed, the paper/ cardboard will smother the lawn and create a happy environment to encourage worms.