Landscape timbers question

I'm considering laying landscape timbers like these along a flower bed down the side of my house. Our lot slopes down in the back (walk-out basement, if that helps you picture it). The area that I want to lay this timbers down is about 80' long. For the first 40' it drops about 20", and for the last 40' it drops about another 60" (which I think may be a little too steep). I don't want to use cheap plastic edging, and I don't want to spend a ton on bricks or stones to line the edge of the bed. Is there a good way to do this with landscape timbers? I realize that I'll have to use a step-down type of method where I put some shorter timbers perpendicular to the side of the house and make a series of smaller level beds.

Also, I'm not too familiar with the installation. I've seen recommendations about pilot holes and 12" metal stakes. If I have to put a few timbers on top of each other higher than 12" total, is there a better way to do this too?

And one more thing... we have a bit of a drainage problem on that side of the house also. That's part of the reason I'm doing this. Mulch gets washed down the hill and grass won't grow where we want it because it gets washed over somewhat frequently. There's a bare-dirt "trail" that runs in the place where grass is supposed to be, parallel to the side of the house and intended flower beds. There are two downspouts from gutters on that side of the house, and some of that black 4" (about?) tubing that carries water to the bottom of the lot out back. I think this is a good opportunity to bury it a bit deeper. I hate this tubing stuff. Any special considerations there?

Thanks!

 

I cant say much to your water problem, but I have those timbers in my yard, about 2 feet high. I drilled 1/2" holes in them and then pounded 4' lengths of rebar (made for concrete supports) into them. This helped them to stay together and stable. Mine are kept from tilting by the rectangular shape I made them in so your idea of the occasional sideways one sounds good to me.

Things I would do differently inlcude:

putting some kind of caulking material in between them if there is going to be dirt behind them. Grass and dirt escaped in a few places so I resealed it later on with a few tubes of silicone. You could also use that spray in foam in between if you were careful to keep it to the side that would not be seen. Probably get more mileage with a can of that than tons of caulk.

I spaced the starting point of each 8 foot piece by 24" so it would have that "brick look" where not all your ends meet up in the same spot.