How does Osmocote work?
The prills are made up of many thin layers of soy coating, all of which contain tiny fissues. Water can be absorbed into the prills to dissolve the fertiliser inside, but cannot be released until the prills expand sufficiently to allow the fertiliser to escape through the tiny cracks. When it’s warm and plants are in active growth, the coating expands and fertiliser is released. When it’s cold, less fertiliser is released.