Supersoil Planting Mix & Soil Conditioner Designed to improve all soils – it is both a planting mix and soil conditioner. Top quality ingredients combine to improve soil aeration and to ensure proper drainage - Canadian sphagnum peat moss, ground fir bark, high-quality compost, and clean sand. Adds moisture-holding ability to sandy soils and helps prevent compacting of clay soils. Contains fertilizers to get plants growing fast, plus iron to fight the yellowing cause by high alkaline soils.