Any water butt will do
How To Make Organic Liquid Fertiliser
It couldn't be easier to make liquid fertiliser and your plants will love it!
Take a barrel with a tap that's not connected to a downpipe. Add rainwater. Then add comfrey leaves (the deep tap root 'mines' the minerals from the soil), stinging nettles and any other weeds (before they have gone to seed) and a shovelful of manure. Leave to 'brew' for a few weeks. Be prepared for the pungent smell and avoid contact with your hands as you will be haunted by it for hours! Dilute 1:10 in water in a watering can and use as a fertiliser on maturing plants but not seedlings and watch them grow. Never buy a proprietory brand like chicken pellets again.
Here are some additional tips that I hope folks will find useful ...
The plants need to be under the water, so I put them into an old vegetable net and pin them down with a rock (tied to a sturdy string to make it easy to remove).
I use nettles as they are easy to find and free, but you can also use comfrey and horsetail, which also are both very effective.
I give my mix a stir each day to mix oxygen into the liquid, which is essential to the survival of the bacteria breaking down the plants.
The mixture will produce big bubbles on the surface which means the fermenting process is happening. You need to keep an eye on this as when it has finished bubbling you need to strain the liquid (this is when the vegetable net is really handy to get the majority of the plant material out!) then I pass the liquid through an old kitchen sieve.
The fermentation process can take anything from 10 days to 3 weeks, depending on the temperature. The warmer it is, the quicker the process.
To minimise the smell, I put a few drops of Valerian and a handful of rosemary and thyme into the mix ... which seems to help a bit.
This is a really easy thing to make with a little motivation and organisation and your plants will love you for it!