Not nettles but my own window herb garden, waiting in line for a taster.
Right now I'm picking nettles like crazy - nettle soup is really a humdinger! I still use gloves and cook my harvest before I eat it (last time I played HaRd Woman my thumbs were swollen for two days). Today, when I boiled three to four litres (about a gallon) of leaves, it struck me that some of the nourishment flows into the first boiling water, the water you normally poor off in the sink. Wouldn't it be possible to use as liquid fertilizer instead? Sure, it isn't a classical recipe for "nettle water"*, but it's worth a try.
Thus I brought out a bucket and cleaned it thoroughly with soft soap, hanged our colander over the rim and drained the nettles. The water proved to be dark brown - definately nutricious. I took the cool water I'd used for cooling the leaves and diluted it (recycling, cooling and diluting in one go - what a hat trick!). Now I had a 'middle brown' solution to pour on a defenless plant.
The choice fell on the cherry tree on the balcony - it'll have its first cherries this year and signals an acute need for nourishment. It helped that the container is big enough to take the entire bucket of liquid. However I poured some on the rose and the watermelon plant since they seemed to need it.
I'll pick more nettles tomorrow, and I have to admit I have plans for the harvest of a month. I hope I'll be able to give every indoor plant a ration a week, and it'll be interesting to see how this works out. Later in the summer the nettles will become bitter, according to consulted expertise, and then I can resort to classic nettle water.
*Nettle water is made by leaving nettles in water for some days. Apparently it smells bad but sustainable growers in Sweden swears by it.