A free and ecological fertiliser

This time last year, I wrote about the 'Saints de Glace', the period of cold weather in May that catches out many a novice gardener.  This year, I'm well equipped with two small polytunnels, a cold frame, and my self built lean-to Greenhouse.  I am immensly proud of this latter because it consists mainly of recuperated materials and the only cost was the twenty euros of plastic to cover it.  Even if it only lasts this year, as my neighbour and father-in-law have predicted, it will have done it's job and for a fraction of the price of a shop bought greenhouse.
So far the spring has been mild, the warmest since 2005 I read somewhere.  Taking advantage of the different protections I have this year, I've got my seeds in early.  Now my thoughts are turning to how I can improve the quality of the soil and encourage the growth of my vegetables.  Every winter I cover the soil with a layer of straw to protect it from freezing.  Then in the spring, I break open my compost bin and dig it in.  A few years ago, I came across a magic formula for a free and ecological fertiliser made from one of the least popular of weeds, the nettle.  In France it is known as 'Purin d'ortie'.  'Purin' translates as slurry a reference to the odur given off by this mixture.  Despite it's smell the liquid is a powerful  fertiliser.
The procedure for manufacturing the fertiliser is simple.  A kilo of chopped nettles is immersed in 10 litres of water.  I have found that it is best to put the nettles in a cloth sack.  The mixture is left to ferment for one or two weeks, stirred once a day.  Once the mixture stops bubbling it is ready.  The mixture is rich in nitrogen and diluted can be used as a plant food.
So with the warm weather the nettles have begun to raise their vicious little heads, I have been out with my shears getting my revenge.  My first batch of nettle fertiliser is on the way to helping me have a bumper harvest.