Prolly not. Do you know what kind of grass? I have Bermuda, but fortunately it is a not-too mutant strain and does die with Roundup. You may have created a paradox of sorts--the landscape fabric of course can't really kill the grass, but protects it from your Roundup. So all the healthy roots are just there waiting to poke up here and there. Either you will have to be super aggressive with the Roundup and spray each twig as it appears, every day for weeks, and even then you may have lots going on underneath and just waiting for the right moment to grow, so you may have to re-prepare the entire bed. You're hoping, I guess, you can smother it. There aren't any real smothering products for sale for your purpose. Depending on what you've got planted, you might be able to remove (and save) the mulch, remove the fabric, Roundup what you can see, place thick layers of cardboard or newspaper over the grassy areas, and mulch over that, and hope it is not the super-aggressive Bermuda or something that grows through wood! So you can read and search about smothering grass, lasagna gardening, no-till gardening and lots of related things. People will tell you things will work or not work, but it all depends on what your actual garden area, plants, grass and so forth are like. So, I have no idea whether you've got a grass disaster or something salvagable. And it depends on whether you just missed a few roots or whether you just put your stuff over living sod of an aggressive grass. How did you actually prepare the bed?

I have exactly the same problem. The landscape fabric and all the dirt/mulch is growing weeds like crazy but I can't grow anything pretty or productive. Also, my back yard is catch basin for the streets around me and now this yard is a puddle 9 months of the year. I'm sick of it! I have to work around some bushes and rocks so a tiller is a hard no. It's going to be a long hard slog. I think I'll just remove some of the rough edges for now, and pierce some spots with an old-fashioned long-handled grampa weeder for planting things with shallow root systems. Will probably take me several summers of back-breaking work to remove this poorly executed mistake.

As Ken has stated, it's hard to gauge how many roots are in and through the fabric without a pic. I have seen this many times and it is one of the reasons I don't advocate for using the stuff. So I applaud your intentions of getting rid of it. I would say that timing is of the essence, along with just how much root system per plant we're talking. You're in NJ, which is, of course, a much milder climate than where I live. So.....there may be time to do the ripping and tearing this year yet and have the plants still have time to recover before it gets cold. That's really the only issue I see here...plants CAN suffer if their roots are disturbed just prior to the ground freezing, or getting anywhere close to freezing. In all other respects, the plants will be better off with the stuff gone. +oM

It is not supposed to be. The ad: Stops weeds Lets air and water through Continuous fibers add strength and puncture resistance Rough surface helps hold mulch in place For questions about this product please contact 1-800-327-9462 Here is a link that might be useful: Propagating Perennials