Can anyone explain to me, an old dog, why there is a geotextile under mineral or inorganic mulch but nothing under organic mulch?
Same purpose and effect, to me.
The issue is that I cannot comprehend why dust, sand, leaves and other material being trapped in between is forced to accumulate to the point that the function is no more given.
This is as argued a philosophy as how much of the wire basket to remove when planting trees. I feel with organic mulch that you are essentially making new soil as the mulch piles up on the planting bed. While inorganic mulches are not top dressed as liberally and do not break down. On an organic mulch bed you are essentially left with soil on top of and underneath the fabric if used(what a hassle). I could really see an argument for a decomposable fabric or news print to finish off the existing weeds that survived.
The inorganic mulch has greater porosity so it allows for more weed growth unless it is very deep. As well, the inorganic mulch would tend sink into the muddy soil underneath when it rains without the layer of weed block or geotextile to keep it separate from the soil. You can place weedblock under organic mulch. Its done here all the time.