Contrary to popular belief, and contrary to its supposed intent, weed fabric is a weed-growing medium.
Weeds root on top of it, in the decomposed mulch, and then into the fabric. Meanwhile it blocks organic matter from reaching the soil, chokes the soil food web, and inevitably pops up and becomes an eyesore. If you pull it out of the soil, you'll see weeds rooted to the mat and dead soil (dirt) under where it lay.
What to do instead
Mulch does the weed-suppression job weed fabric pretends to do, without the harm. Lay it three to four inches deep, kept several inches back from trunks and stems.
Use coarse to medium mulch, around three quarters of an inch; arborist chips or your own chippings are the best. Fine mulch packs down, stays wet and grows weeds in the mulch itself, which is the same problem the fabric has.
Organic matter goes on top, as mulch. The soil life takes it down at its own rate, which is the rate the plant can use it. Fabric stops that from happening.
Mulch and living ground cover shade weeds out before they start, which is less work than cutting or spraying. For the stubborn ones, bermudagrass and oxalis, smother them with cardboard under thick mulch.
And don't till
Tilling was standard for a long time, mostly a carryover from farming, and it is the quickest way to damage the soil's structure. The fungal threads that carry water and nutrients between plants live in the top few inches, and a tiller cuts them to pieces. Turning soil deeply also scatters what survives through far more soil than the fungi ever occupied.
Undisturbed soil keeps its structure and its pores. New roots follow the paths old roots left and find the fungal network already in place.
The exception is severe compaction, where nothing will grow until air and water get back in. That is a repair. It is not an annual practice.
The full rule, with its illustrations, is in Southern California Landscape Maintenance: Ecological Maintenance, Simplified, at rootandbranchdesign.com/book. The first chapters are free to read at rootandbranchdesign.com/book/sample.
Contrary to popular belief — and its supposed intent — weed fabric is a weed-growing medium.