Posted: 15/03/2015 at 09:18
You could surround the container with attractive large stones, small boulders, flints, pebbles - whatever you can dig out of your garden or find at the GC. This would hide most of the sides of the pond liner & you could then plant some of the trailing plants suggested above to trail over them. If you choose your stones carefully you might even be able to push compost into the spaces and grow the sort of plants which thrive in stone walls.
To finish it off I would top dress the pond liner with pebbles.
(It's a mini rockery really!)
Don't forget to make some drainage holes in the pond liner unless you want to grow bog plants.