How long does liquid tomato food keep?

I have some in my shed that's at least two or three years old.  Will it still be OK to use?

Mine's still going strong and I've no idea how old it is.

Just make sure you shake it first.

I have never kept any more than a year I feed the flowers in the border with it begonias love it .
I also have a few tubs that are filled with plants that are upto ten years old so I use it all year round to keep them in tip top condition. The only plant I have found that you have to be careful with is pansies it doesn't mind the feed but you have to make sure you don't splash the leaves as it can scorch them.
John

Thanks everyone.  I used the stuff and all was well - until we got blight!  Better luck this year.

  ditto BQ