Answer: Usually, gardeners will remove landscaping fabric prior to planting perennials. The soil will need to be deeply prepared and amended to provide a good growing environment for the perennials, and this is impossible to do with the fabric in place. Most perennials also increase in width over the years and need room to expand. Some will also self seed over time and need to be able to root deeply.
During the preparation and planting phase it is easier to rake the mulch aside. It can be reused later, although a woody mulch can temporarily tie up the nitrogen in the soil. If you reuse the mulch, be sure to apply some additional nitrogen to compensate for that. Alternatively, you could use chopped rotted leaves, double shredded hardwood bark, half finished compost or a similar material. Whichever mulch you use, it should be layered only two or three inches thick and should not touch the plants.
You may also want to add ample amounts of organic matter to the soil to prepare it for the perennials. You might also run some basic soil tests to see what other amendments if any need to be added. Your County Extension should be able to help you with the tests and interpreting the results with an eye toward growing perennials.
Enjoy your new perennial garden!
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