Anne Get an old meat cleaver -- if you lived nearby I have one you could have -- and use it to make your slot. You could certainly hammer it down to break the roots apart. It would take some time if you have a hundred feet to go, but it would do the trick even if it was slow going. I suppose a square shovel would let you do the same thing, probably much quicker! Then, as you note, you could use a cheaper material for the root barrier. I've no idea how long grass roots are; it must depend on the type. But you could water a small area until it's soggy and gently pull up on some of what's there to get an idea of the root length. With a barrier AND a 10-12 inch extension, you aren't likely to get much invasion from the other side!

I see you're in TX as am I. Gravel reflects a lot of light and heat so I don't really care for it especially around veg. I would go with cedar mulch over a weed fabric (you could also put cardboard under the fabric). If you have a slope problem, then try putting down a one by one piece of wood to keep the mulch from washing down hill. Just lay it on the ground... doesn't need to be nailed into the rock. I have the same problem by the way. I'm on the side of a rocky hill. I'm building raised beds, slowly but surely, in a pattern. I'll eventually have mulched pathways inbetween. Right now the weeds aren't a huge problem. I like the idea of mulch instead of rock because it will let natural rainfall slowly penetrate the ground. I'm currently using cedar mulch in all of my flower beds which are on gradual slopes and the mulch I bought 7 years ago is still holding up, not breaking down, or washing away.

a plan usually starts with some goals ... do you have any goals.. other than just filling it up .. do you want to block a sight line ... either towards the house.. or away?? stand inside that picture window.. and look out ... what do you see??... do you always want to see it ... or do you want the neighbor always looking in??? from the car.. the last pic.. do you want to be able to see the door coming in??? .. perhaps a safety issue???? once you can state some goals ... then you can come up with a concept ... and ONLY THEN ... do you start picking plants ... ken

A walkway to the sidewalk is always nice. It's a distinguished home, even TPed, and deserves a welcoming walk. When I've done a similar project, I hired a landscape designer that was not affiliated with anyone and she drew up the hardscape and suggested plants. With the plan in hand, I was able to get someone to do the walks and other hardscaping and I could then do the rest at my own pace. So, I recommend finding an independent designer.