Question
I would like to put a border around our patio slab. I will fill it with cedar( shredded..lol)
would I put the 4 inch plastic grass barrier next to the 1.patio cement  2.cement, border, then black plastic 3 or next to the grass.

thanks

Answer
Glenda,

I would not put a plastic border anywhere.  You do not need it by the cement.  At the grass bed interface do the following:  1) make a straight cut downward at the edge of the bed and 2) make second from inside the bed at 45 degrees back to the straight cut you made in #1.  This will create a nice edge at will hold your mulch and allow you to run your lawn mower over the bed edge and, this is the best part, you will not have to use your string trimmer.

Good luck

Gary