Prep the ground? I just smoothed it out. The best part about SFG is that you don't have to prep the ground. The garden goes on top. I'm assuming you mean bare dirt. If you have grass, that's another story.

I do have grass and that's what I'm trying to figure the best way to take care of.

All you have to do is put landscape fabric or lots of cardboard down on top of the grass and then just fill the beds with the good stuff. Grass will eventually die.
Keski

If you have bermuda (or St.Augustine), you may want to try to dig it out from the area. It is very tenacious and will sneak up into your bed. If it's just a blade grass, cardboard, layers of newspaper and landscape fabric will take care of it. It will just die out under your raised bed.

I put down cardboard and built on that. Have not had grass or weeds come up. Now that my raised beds have been there for 1.5 years, I am thinking about using daikons in the fall to loosen up the hard impacted ground below my beds. Got the idea from reading about tillage radish.

How can you tell if the grass is Bermuda grass or some other type? I'd like to avoid digging the grass up if possible.

We also rototilled the ground under the beds, to loosen up the soil an extra 8 inches or so, to allow roots to penetrate deeply. I've read that even driving a spade or broadfork into the ground every few inches and rocking it back and forth a bit to create "fissures" in the subsoil would help, if you don't have a tiller.

Bermuda grass and St. Augustine have runners, long stems that run parallel to the ground. They spread out sideways and underground. Bermuda grass is extremely difficult to get rid of. Other grasses grow up in little clumps. If you pull out a clump, it is not attached to any other grasses. Those types of grasses are easier to get rid of. Cover it with a few layers of wet cardboard and put dirt over it.

That's the beauty of the SFG. No prepping necessary. I have a mix of Bermuda and St. Augustine and simply stapled weed block fabric to the bottom of my frame, placed it where I wanted it and filled it with Mel's Mix. No grass, no weeds, and I really believe the layer of dead sod/mulch below the fabric helps it breathe and drain.

I am following this and have Bermuda. 12" bed going on top. Advise on killing it? Landscape weed block?

Bigtex52. How deep is yr bed?

If you have Bermuda anywhere in the area, you are going to want to kill it to keep it from invading the bed. I would suggest a pump sprayer while wearing protective gear, applying the strongest allowable dilution of a Roundup equivalent, followed by digging up and removing the root zone under the locations of the future beds and replanting with a less invasive grass over the rest of the area.