Drop a bit in some vinegar, if it is lime it will fizz.

could it be fish/blod/bonemeal? is it a fine powder? if in doubt dont use it.

You don't know what it is so I would suggest that you take it to the Local Authority disposal site and give it them to get rid of.

Hi there,

Uummmm a tub of White powder could be anything from ant killer to hormone rooting powder, I woudnt risk keeping it, unless you can ask the last owner.

Happy gardening.

further to my question, the tub its in is quite a large tub, the powder is very fine like flour and is white

As others have said, could be anything - recycling centre I suggest - not only do you not know what it is, it may be old, and chemicals do break down and may become toxic over time, even if they weren't to start with.

White powder - make sure that the local Mafia boss doesn't come looking for it :-(

Ha ha, Bulbaholic - yea, I wouldn't recommend getting out the mirror and straw either...

If it won't mix with water it's probably no use to you, or the plants, get rid and make space for something that is!!

thanks for all the responses, i think the best thing to do is as someone suggested, take it to be disposed of,