What you really need is loo roll cylinders. They need a long root run. So a 2-3 inch pot wouldn’t really be tall enough, but half a kitchen paper cylinder, or a loo roll centre would be better. Or make a long pot with newspaper.

Make sure the soil is lightly moist & carefully ease out onto newspaper or something so that you can gently tease the plants apart. Young sweet peas benefit from potting on into a long, narrow container so rolled up newspaper tubes will be better than plastic pots. You can plant the whole thing as the damp paper will break down in the soil. Early pinching out of growing tips helps to increase the number of new shoots

I would avoid the ones in pots and have a go at growing from seed. There is still time. I find that the method that Karen suggests by making tubes of newspaper by wrapping it around a plastic tube. Fill with compost and sow individual seeds in them. You can then plant the whole thing, paper tube as well.

Thank you for the advice and ideas about making paper pots. I will not be buying any from the stalls but will buy some seeds and a news paper.