How tall will your raised beds be? If less than 1 ft. than you need to take the grass out because roots will need to access the soil. I'd only put landscape fabric down if the beds were over 2 ft. high.

Thanks. I'm looking at purchasing one of the Greenes raised beds. It's 48x96x10.5. These beds do have the ability to be stacked so I could make it over 2' high if I wanted. I'm trying to cut out having to till the existing section where I will put the bed and also to keep weeds and critters like moles out.

I am not a fan of landscape fabric in most instances since it can create issues with water and nutrient movement through the soil and can restrict root growth, though personally I've only had issues with woody plants, so I don't know about how severely it could impact veggies' roots since I haven't used it in my veggie garden. I don't think I'd want it in a veggie garden since I grow root veggies, and I think it would interfere with harvesting things like potatoes and carrots. Landscape fabric also won't keep critters out since they can and do chew right through it. I would put down a layer of corrugated cardboard (no colored print on it) to help smother the grass, and then a layer of hardware cloth (1/2" or 1/4" wire mesh) to keep out the critters. Then set up or stack your beds and fill with mixed soil and organic matter. By the time the plant roots reach as far as the cardboard, the grass and the cardboard will be rotting, so the roots can grow down into the soil below. Be aware that unless you kill the grass around the beds (I did it by smothering with cardboard and mulch) some grass will grow up into the beds from around the edges.

Never start a vegetable garden without doing a soil test first. You want to be sure there isn't lead in the soil. Just choose the routine soil analysis for home gardens. http://soiltest.umass.edu/ordering-information

Steve

For our raised bed for veggies we did put down landscape fabric right on the raked ground. A double layer and then ran it up the sides of the bed also. Didn't want the soil to leak out were the 2 cedar planks meet. Filled it with our old garden soil, and amended it with manure, seaweed, and veggie soil. The only root veggies we grow are potatoes. We grow them in collapsible nylon laundry bags. Works great believe it or not. We have grown heirloom and roma tomatoes, brussel sprouts, beans, hot and regular peppers, lettuces and herbs in the raised bed without any critters getting in. We lay soaker hoses winding through the bed for watering and put a flexible fencing around the bed attached to the posts.

We installed new wooden raised beds in 2014. We used hardware cloth nailed to the bottom to keep animals from digging up through, but no landscape fabric to 'line' the bed. We have used landscape fabric and bark mulch in the aisles to keep the weeds down.

I agree with NHBabs - layers of cardboard to get rid of the grass and weeds. I've done that multiple times and it works great. Hardware cloth to keep out critters yet allow roots to go down into the soil below the frame. Why would anyone want to restrict the root system to as deep as the bed and no further? The deeper the roots can go, the better result you will have.