Answer: If you use a landscape fabric it should be air and water permeable. Usually though, thorough weed removal prior (including both annual and perennial weeds) to planting followed by maintaining a steady layer of organic mulch that is regularly raked and topped up will prevent weeds. In my experience, the weed fabric slows the natural break down process of the mulch, thus reducing its effectiveness as a slow release way of feeding the soil over time. And, if weeds do get started on top of it, their roots tangle into the fabric making it difficult to remove them. You might want to consider using a ground cover plant to crowd out weeds between shrubs. This can be easier to maintain over time than a mulched area. If you use a ground cover plant, you would not want to use landscape fabric as that would prevent the groundcover from rooting effectively. I hope this helps.
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