Whether wood, plastic, stone, masonary, or metal, there are a lot of different products to border gardens and flower beds with. It may be a purely asthetic thing but usually the purpose is to keep the grass out of the gardens.
The year before last I used cedar and pressure treated 2x6s to border my vegetable garden. This year I used composite decking to border the flower beds. In both cases the materials I used were chosen because I was able to get a deep discount due to damage. This is not a problem since the damaged side always got buried.
And by the way, it's been quite a few years since pressure treated wood has used arsenic. Today's pressure treated woods are supposedly greener. I say supposedly becuase there is still debate over their toxicity, but I made my choice and you can make yours.
In the video below you'll see how I built a simple bending form and wrapped visqueen around the section I wanted to bend. Using a wall paper steamer I fed the steam into the visqueen bag to heat up the composite decking material before wrapping it around the bending form. The first time I did it I steamed for about 45 minutes. The second time only about 20 min. Steam bending is usually done in a box but the nice thing about doing it this way is that you can test the elasticity of the plank before committing yourself to the full bend.
I bend wood often and the nice thing about composite compared to wood is that there is almost no spring back with the composite. With wood there is about a 10% - 15% spring back. So with composite what you get is what you get.
The next short video shows the finished product. I made the curves with mowing in mind. My riding mower can get around the curved corners easily. I still have to use the weed eater but with a little practice I can walk right along and quickly trim it.
The last short little video is a demonstration of how I saw my kerfs using a circular saw and a speed square. Rather arbitrarily I use the distance between the saw blade and the right edge of the bottom plate (sole) of the saw. The kerfs are cut a little over 2/3rds of the way through the board, or a little over 1 inch. The garden is 14 ft. wide, so I radius these boards 7 ft. which works just fine.
Please go to any of my Youtube videos and SUBSCRIBE in order to follow future OpenWoodShop.com