Wood Ash as Fertilizer

Q.  I have been searching for information regarding ashes. Here is what I have found. Good clean ashes from burning untreated wood is good for your lawn and garden.  It is powdered nitrogen.  I intend to put it in my spreader and broadcast on my lawn. I barbeque with maple sticks that fall from my trees.   It should green it up nicely.

A. You have received bad information regarding wood ashes.  They contain no nitrogen.  The main ingredient is usually calcium carbonate, which can be good for your ground in measured amounts, if you have acidic soil (low pH because of more than 20″ of rain per year).  However, if you have alkaline soil you certainly don’t want the pH raised any more, so DO NOT put ashes on your alkaline soil gardens.

There is an essential nutrient – one of the “big three” – called potassium.  The compound in which it is most often found, and in which it is used as a fertilizer in the garden, is K2O and is known as potash.  The reason it’s called potash is because it was discovered to be an ingredient in ashes.

Care should be taken to know what you are doing before applying anything to your garden.  Wood ashes also contain heavy metals that might actually be bad for you.

I recommend anyone considering using wood ashes in their gardens read the materials listed below.  The first one is particularly well done.