The soil in my greenhouse is a heavy clay subsoil. I want to grow various woody perennials in the greenhouse, including figs and other small trees. What would be the best growing medium to fill a permanent bed without breaking the bank?
My primary sources are my friends' goat bedding (aged), my chickencompost, and wood chips from a local arborist. I have added wood chips atop my large section of clay, and more diverse plants are starting to grow on it.