Seed bombs (or seed balls) are made from a mixture of clay, compost, seeds and water. The clay in the seed balls helps protect the seeds from being taken by predators, and also helps to retain moisture once it becomes wet by rain, which germinates the seeds. The compost supplies nutrients for the establishing plant.
Seed bombs have been successfully used globally for revegetation after bush fires and droughts, in barren areas, to establish food crops and in small scale garden /vegetable plots.
This fact sheet, compiled by Dick Green, contains a useful guide on how to make and use seed bombs, along with the benefits and potential issues with their use. Download the Seed Bomb Fact Sheet here.