The finer the wood, the faster it breaks down into a compost mixture. You do have to add some soil or sand to it to keep it from compacting too much when it does break down, but you don't need a lot of dirt. I live in Florida where the soil is quite alkaline and the pine fines seem to provide the needed acid in the planting mixture. For plants that require alkaline soil, they may not do as well in a pine fine mixture.
When the pine fines have completely decomposed, the soil in that area is beautiful. Dark, rich, and has a really nice earthy smell to it. I typically find a lot of earthworms in the that type of soil, too! The plants seem to thrive in it. I have also noticed over the past few years that more and more plant nurseries are using pine fines in their potted plants. It actually makes transplanting easier (in my opinion). I swear by pine fines!
