A crop grown specifically to be incorporated into the soil while still green to improve fertility and soil structure. Leguminous green manures (clover, vetch) fix atmospheric nitrogen.
Green manure is an economical and environmentally sustainable way to boost soil health across Australian gardens. By growing nitrogen-fixing plants like legumes (peas, beans, clover) or fast-growing crops like oats or rye, you can then turn them into the soil to decompose and release nutrients. This practice is particularly valuable in Australian gardens where soil quality varies greatly between climate zones.
Timing is crucial for Australian gardeners. In temperate zones (zones 8-10), autumn (March-May) is ideal for sowing green manure crops that overwinter and establish strong root systems before spring digging. In warmer zones (6-7), spring (September-November) works well. Winter (June-August) is perfect for cooler regions to grow crops through the mild season. Avoid planting during summer (December-February) in most zones as heat stress reduces effectiveness.
Common Australian green manure crops include lucerne, which builds deep roots and fixes nitrogen; clover for rapid biomass; oats for carbon-rich material; and lupins for acidic soils. You can source seeds from Bunnings or specialist suppliers. Dig the crops in when flowering begins, allowing 4-6 weeks before planting your next crop. This method works beautifully alongside composting and mulching strategies to create rich, friable soil without excessive fertiliser use.