Question
My husband says using ashes as fertilizer is good.  I say it is good in limited quantities and well spread out, not clumped on.  He also uses ashes from the bbq grill the same way.  Is it safe to use bbq grill ashes as fertilizer?  We use charcoal, parifin starters, lighter fluid, and different wood chunks in the grill (not all at the same time).

Answer
Wood ashes are ok as they add potassium but use it sparingly as it can raise the soil pH rapidly. If you live in a region with naturally acidic soils then it can be used in place of lime (if you lime) but do not use lime and ashes at the same time. If you live in an area with naturally alkaline soils then wood ashes would not be a good idea. A light dusting is all you need.

I don't know if bbq ashes are different, but I doubt they provide much nutritional value for the soil as the potassium (released during burning of wood) may not be present in charcoal. In fact, I would be very surprised if it does contain plant nutritional elements, but than again I have never actually tested charcoal ashes for plant nutritional values.