Regardless whether you’re in the UK or the US you may be paying too much for your liquid fertiliser.
Making your own is so easy you’ll wonder why you never did it before!
All you need is a watertight container (such as a bucket) and err, some nettles and water. Stick nettles in water in bucket and leave to brew. Tada! Horendously smelly fertiliser!
More indepth details here: http://www.nettles.org.uk/nettles/activities/nettlemanure.asp though whether the additional steps make the blindest bit of difference in the long term I wouldn’t like to say. What I do does the same job, it may just take a little longer.
My newly made fertiliser container is made from a discarded council green waste bin. I drilled a 25mm hole in it, stuck in a water butt tap and filled with nettles and water. The good part is that the bin has a close fitting flip lid. This stuff stinks, but at least now I don’t need worry about offending the neighbours.
There’s some talk about even using horsetail and how to make a nettle brew smell nicer http://www.seasonalgardener.com/Tips/Liquidplantfertilizer/tabid/3190/Default.html