I tried to start sunflowers in teabags last year to no success at all , i suspect they dry out too easily despite me watering them when they looked like they needed it .
there must be a simple origami bag/box that could be made out of rice paper type material , sown in the autumn when damper might just do it
There was a post a while ago about using the fibre based plug pots filled with soil and sealed up at the end , the very small ones are a good size and very strong until damp.
maybe soil in teabags with a few `water retention crystals` would do the job , this material is commonly available in garden centres - it absorbs massive amounts of water and expands to hold it .

bB
