Ever since my (veteran gardener) mother told me about this method, I have used toilet roll inners as biodegradable pots for vegetable seeds. They work well for peas, beans, carrots and even sweet peas. My mother uses them for everything, including flower seeds. For vegetables, once the roots appear below the pots, sink them in the soil at the same level. They rot away. Some organic purists don't like the glue used on the cardboard but once you go down that road you'll end up beating your unworthy self with thorn branches..
