RHS Sylva Grow Farmyard Sylva Grow Farmyard is made from anaerobic digestate which is a by-product of renewable energy production. An excellent soil improver that provides gardeners with a 100% peat-free, rich source of organic matter for all soils. Sylva Grow adds nutrients to the soil, which improves fertility & yields. Enhancing soil structure & workability & increasing water-holding capacity. Sylva Grow is exclusively obtained from a partnership with the Duchy of Cornwall & local farmers near Dorchester, Dorset. Containing up to 20% certified green compost for a further organic matter boost.