I ordered water lilies off the internet for the planters, picking the tiniest dwarf flowers I could. I ordered from Water Lilies direct as they had the best choice of pygmae (mini ones) I could find. Tim Science (who plays a mainly advisory role in the garden) fancied a red one, but as usual the broad choice diverted us, a I ordered an apricot coloured Nymphaea Aurora, and Nymphaea Laydekeri Lilacea, a pink and white super-miniature. Here they are settling in - and what's that growing with it?
Duckweed. It came in with the seed water from the ponds (a bucket of water taken from an existing pond, which is a crucial part in making sure you get water snails and other beneficial beasties). Rough with the smooth, and like all my other perennial weeds, it'll compost just fine.