[Judd]

I've been given a 5 ltr tub of this from a friend,he got it off a local farmer.
Is it any good to me?

[Yorkie]

Do you mean sulphate of potash?

Potassium is one of the vital ingredients for plant growth; it stimulates flowers.

Yes, it will be of use.  I'll leave it to others to explain how! 

[Judd]

That's what I thought,it's not in the original container so he might have been mistaken.

[solway cropper]

If it's not in the original container I'd be very wary of doing anything with it other than chucking it in the bin. If you don't know what it is how do you know what it's going to do to your plants?

Potash stimulates fruit production which is why it is an excellent tomato food.

[Judd]

It was given to my friend especially for me to use on the allotment just a couple of days ago,it hasn't been sitting around on a shelf for years so I think my friend has probably just got the name wrong.