Question
I understand that wood ash is the donor for potash and that this is good for the garden. I live in France and burn wood for heating. Q, can I use too much ash on my garden?
Thanks,
Ted

Answer
Wood Ashes by the pound were recommended thru the 19th century (V. Sackville-West and others) for Lilacs and their relatives.  But too much of a good thing is still too much. Robert Lippert, PhD, a respected Scientist at Clemson Agricultural Center in Geogia, maintains a website on Soil, including a page on 'Best Management Practices for Wood Ash Used as an Agricultural Soil Amendment':

http://hubcap.clemson.edu/~blpprt/bestwoodash.html

Dr Lippert reports: 'Calcium is the most abundant element in Wood Ash and gives the ashes properties that are similar to agricultural Lime. Ash is also a good source of Potassium, Phosphorus, Magnesium and Aluminum.  In terms of commercial fertilizer, average Wood Ash would probably be about 0-1-3 (N-P-K). In addition to these macronutrients, Wood Ash is also a good source of many micronutrients that are needed in trace amounts for adequate plant growth.'

Is it good for your plants?

He says yes.

'Several studies have compared plant growth using both traditional limestone and Wood Ash and most have concluded that ash gives better growth responses than limestone.  While some studies have reported detrimental effects at extremely high application rates, these responses were explained by the drastic increases in soil pH beyond the plant箂 optimal level.  As long as the soil pH is maintained at the proper level, productivity will be enhanced by using Wood Ash as a liming agent and soil amendment.'  Since Ash pH can run from 9 to as high as 13, a Soil Test is important.  He recommends applications on days when high humidity lowers the dust as you apply it.

Good question.  Thanks for writing.