I have made comfrey feed in the way that is usually recommended. Soaking the leaves in a bucket of water for two weeks. Apart from the vile smell, which is not to be underestimated, it can also attract flies and fly larvae if you don't cover the bucket completely. The smell is so bad that you should really warn your neighbours before using. I have had it on my hands before and it doesn't wash off. I am not really that fussy about smells and so on but when I wash my hands I want them to smell of soap.
So carry on an make this vile brew if you like but here is a better way that I have been using for years.
This is my comfrey patch:
It is a lovely plant and the bees love it so that is always a bonus. It is very vigorous, as you may have heard, and difficult to eradicate but the advantage of that is that you can keep cutting it and it keeps growing back. You can cut it right to the ground and add to the compost heap and it will bounce right back.
I grow it in a difficult patch next to and behind a water butt and it seems very happy there.
This is my comfrey tower.
You stuff the leaves in the top and a dark liquid starts to drip out the bottom in a few weeks. It doesn't smell of roses but it is not nearly as bad as the soaked brew.
My tower is just inside the green house door. This has the advantage of being dry and the heat probably helps the leaves rot down more quickly. You can also fix them onto the side of a shed or wall or anywhere you are able to bang in a stake. This one is cable tied to a pole (rusty but that is not necessary).
It is made out of a 4" uPVC plumbing pipe. I took it down today to clean out the residue from last year.
The end cap has a hole made in it to allow the liquid to drip out. Some wire mesh is lodged just inside the pipe to stop the hole clogging with goo.
If you only had a pipe you could wrap wire mesh around the bottom of the pipe which would allow the liquid to drip through but hold in the rotting leaves.
You cut the leaves and stuff them in the top:
They are quite hairy so it is best to wear gloves. Any left over stems go in the compost heap.
Then you use a plastic drinks bottle full of water to weight down the leaves. Tie string round the cap so you can pull it up.
Under the pipe I have a funnel and a jug to catch the juice. You can also use a drinks bottle or milk bottle to make a funnel and container if you don't have a jug. Cut off about 15cm from the top of the bottle and invert into the base. I did that until I found this jug.
It is a thick black liquid which you can then use diluted 10-20 parts with water. I aim to top up with leaves every couple of weeks and this ensures a constant supply of feed.
You cans see that this has been in use for a while but apart from cleaning out the rotting leaves once a year, I don't have to do any maintenance. Just keep adding leaves. Easy!