Large masonry supply stores will have vitrified crock in square, rectangular, or round shapes with open ends in various diameters and lengths that would be suitable for your intended use. The color is usually a red/brown mix. I'm not sure who might still make them, but cement culverts in varying diameters and lengths might still be available. Use a hand cut-off saw to cut to length & bury the rough ends. Gas pipe comes in diameters up to 3 ft. Check at a welding shop to see if it is available. They would be able to cut to length. Build your own square or rectangular planters from cedar and/or treated lumber. Al

Hi Paul, I also have a bermuda lawn problem and the only solution for me (I've tried many) was to put plastic under the box and cut holes for drainage in the plastic. It has to extend out from the box at least 2 inches. I usually lay down cardboard in the box to absorb most of the excess water. I also have tree roots and this helps. The weed cloth didn't work for very long, but it's 2 years now without a problem using the plastic. Hope this helps. Kath

I also agree that you are limiting yourself somewhat needlessly. There are lots of options, but I understand if you are not comfortable with a lot of them. How about something like this Jasper blue/gray subway? I think that would look really nice while adding a hint of color, but is still understated. :) Link

This forum is to help people to grow real grass, but you might get some help here. One thing you might ask when you're talking to retailers is whether the grass has a slipperiness factor when wet and when dry. This is the question to ask when selecting tile for inside a shower. Surprisingly some rough tiles are slipperier when wet than some smooth tiles. I realize I'm projecting a tile quality onto a plastic, but you might ask about that. The professional football type of artificial turf is filled with spongy little black balls. If the grass is 1 inch high there are probably 1/2 inch of balls in there. I don't know why they're there but it seems they would cushion the fall for the players much better than a few blades of plastic.