I think tomorrow they're going to have to go into a bigger box - they're crawling over each other in their present one.
Saw these weeds at a friend's house yesterday, and recognised them as horsetail or marestail. Apparently it's possible to get a green colour from them, so I picked a carrier bag full and brought them home.
Today I chopped them into pieces and put them in a large pan of water to heat. I boiled them for about an hour, and left them to cool. When I checked the colour of the water this evening, it's very weak and watery. I really can't imagine them dyeing anything pale yellow, let alone green. Maybe it was too late in the season? Perhaps they should be younger plants? I will try a small sample of wool to see what happens, but don't expect much from it. If anyone knows what I've done wrong, I'd be grateful for any tips.