I see a lot of the palisade type installs are for polymor or 'log rolls' that are small diameter pieces of wood.

We were looking to do roughly 45 feet of either treated 2x4 or 4x4 wood that we would saw cut to slightly different lengths and put them in a row as a divider/edge. The wood would be set vertically. On one side would be a planted area, the other side grass. Each wood piece will only come out of the ground somewhere between 6 and 10 inches.

I'll have some excavation equipment available so digging out a hole/trench will not be an issue.

While trying to see how to properly install these, I seem to miss how they would be 'fastened' into place as to not lean/move/buckle over time.

What is the correct process for figuring out how deep to cut the trench, how much leveling sand/rock?, to add and then how to actually fasten the wood so it stays put?

Thanks!