Abstract: A method of composting “green waste” to provide growth media, particularly for growing fungi of enhanced flavour and shelf life, is described. The growth medium comprises a graded mulch of “green waste” comprised essentially of grass and hedge cuttings, however, wood chippings, bark, leaves and vegetable and fruit materials may also be used, together with a density modifier, such as straw, and a nitrogen additive. The growth medium is regulated to enhance growth and availability of water and nutrients during the growth of spawn into harvestable fungi. The growth medium may be adapted for use as a mushroom spawn carrier and as casing material. Additionally, a compost material suitable for domestic and more general horticultural use is provided. A soil cleanser and/or improver is also provided.