Q: We want to cover the ground in our island with something that weeds won’t grow up into and through. We have considered gravel on top of landscape fabric. A friend did something similar with rubber mulch but the grass grew up through it. What could you recommend for a permanent solution to weeds growing up in the bed?
A: There is no material that weeds won’t eventually grow UP through or DOWN into….. except solid paving like concrete or asphalt.
Your idea of putting stone over landscape fabric would work for a while until falling leaves decompose and make a humus layer between the rocks. Blown-in weed seeds will germinate in this and will be a nuisance. I suppose you could religiously apply a pre-emergent to the area every spring, summer and fall to prevent weed seed germination.
My personal preference is to cover spots like this with pine straw or chips and then make a weekly weed-killing visit with a spray bottle of Roundup.