No - wood ash is valuable as fertiliser provided that you were not burning
CCA preservative treated timber.

But don't use coal ash on the garden - too much heavy metals and there can
be enough boron to be toxic to plants.

Regards,
Martin Brown

Suggestions for what to do with coal ash would be appreciated. It isn't
proper coal it is one of the 'smokeless' oval types and does have a bit of
wood ash mixed in. I don't need it for gritting the drive in ice and snow
anymore and there is quite a heap now!