Looking at the crafting nodes I have been working on for the private server version of NexusTK I am running, MornaTK.
The mobs will produce seeds which then mature into the new plants and drop more seeds through the plants lifetime. Mineral nodes propagate across the map as well, gathering the minerals from soil and water around them. For the "living" nodes, things like sunlight, proximity to water and the type of tile the seed landed on will dictate how quickly the mob can mature and begin dropping seeds, as well as how frequently. This is just an initial look at the test map shortly after placing the seeds.