[Rob the rake]

Does it have a use-by date? Several bins of comfrey and seaweed "teas" from up to two or three years ago lurk in various corners of the plot; does their usefulness/potency wane with age?

[Russell Atterbury]

I used Burdock leaf and seaweed tea's that were 2 years old and really manky looking on the top of their 5lt bottles. And the result was as normal. I use these feeds more than the recommendations because of poor quality soil, and  I have to say that most things I grew performed excellently.