You need hundreds of years of ash from the fireplace and the contents of the pot to make a real difference
So it adds iron as well, great!!I always empty the ash pan from log burner into the flower bed in the garden, I can honestly say that the only difference I’ve noticed is the increased level of nails and screws in the soil………
I covered 1 row of my sweetcorn plants with wood ash and havent noticed any difference to the other rows. I thought wood ash was rich in potash?