I found a piece of large-diameter PVC pipe left over from a previous project and decided to use it as a plant holder. It can be used on the porch or patio. Even if you have no place to hang plants, it raises them up to a level that makes them easier to care for.
Of course, the plain white color of the PVC may not blend in with the area, but it is easy to make them any color you desire by using latex-based paint.
I tried a few, and I found that they could even be used in the garden, where they blend in with other plants.