Google thinks that people have been making clothing out of nettles for over two thousand years – he found it on the Internet, so it must be true.
Probably, on someone’s time-line from around AD 0 or so, there is a picture like the one we have today. The status says “Must get back to the retting and scutching – that sounds like my hubby’s oxen in the drive!”
First, you need a big pile of nettles. Then we come to the retting. Tie the nettles up in bundles and dump them in the nearest pond or stream. You might need some rocks to weigh them down.
Set the kitchen timer for eight days and go and have a cup of coffee. When the timer goes off, take the nettles out of the water and spread them out to dry. When they are thoroughly dry – bundle them up and put them back in the water for a few more days.
Take them out of the water, let them rest for a while, then run them through the mangle – of course you’ve got a mangle, it’s in the shed behind the kitchen, with the big copper boiler you use to wash the clothes. Now, spread your nettles out and beat the living daylights out of them with a big stick (this is the process, less threateningly, known as scutching). Sort out the longer fibres, spin them into thread, weave them into cloth, and you’re done.
Otherwise, you could just chop the nettles up small and feed them to the chickens – suit yourself.