Penobscot Blend Compost & PeatPenobscot Blend Compost & Peat Uses: Planting amendment for annuals, perennials, shrubs and trees; conditioning garden beds and borders. Also terrific for growing vegetables! Coast of Maine Organic Products Penobscot Blend Compost & Peat is a rich, smooth, all in one planting mix made from salmon and blueberry compost, tiny mussel shell fragments and peat. Mixed with native soil, it helps aerate and add texture and promotes better root growth. When