It didn't seem like it would be too much work to strip the leaves off the couple of fallen branches I found last week. I'd already stripped them for bark anyway...
This dyebath came about slowly - I steeped them in water for a couple of days before simmering them, and then left the mixture overnight to cool before straining. I have no comparison really, but my gut tells me it was worth it. The dyebath I ended up with seemed like a bit of a liquor, rather than coloured water, and it was deep and rich.
A couple of skeins went in the dyebath. An undyed skein, and one of the dandelion dyed skeins from a while ago, just because I wanted to see what would happen. Given the paleness of the dandelion skein, I'm actually surprised there was much of a difference between the two.
100g birch leaves, soaked for two days in cold water, simmered for one hour then left to cool overnight.
25g undyed wool yarn pre-mordanted with alum and cream of tartar, and 25g of wool yarn previously dyed with sunflowers
all simmered together for one hour then left to cool in the dyebath overnight before rinsing