Raised Bed Garden Assembly Organic compost, peat moss, vermiculite, weed cloth and the frame are already to be assembled. Build the frame and assemble items for soil mixture.A layer of weed cloth prevents weeds from growing up through the garden. Use a large tarp to mix the compost, peat moss and vermiculite before adding to the bed. PVC tubing can be added to provide support for plastic sheeting in cooler weather. Add plants and watch them grow.