If the bonfire contains only old plant matter or wood which has no preservatives on it, then it can be used around plants, (not on lime-haters) but it is best to bag up and use dry in the spring as it contains a little potassium. If you just spread it on the ground then it will be quickly washed away by the rain. If the bonfire was a mixture of general waste, then bag up and send it down to the local tip.

Thank you. Am not sure what the problem with potassium is but will look that up online!

HI JLC44 I HAVE HAD A BONFIRE EVERY YEAR FOR 20 YEARS ON MY WASTELAND AS MY WIFE CALLED IT,GOT MY SHOVEL OUT DUG IT ALL IN & TRANSFORMED MY GARDEN WITH SOME GOOD TURF 3 YEARS ON & LOOKING GOOD

We use all the wood ash from our stoves on the garden, not so much as a fertiliser, because it doesn't have much in the way of useful minerals, except, as Jimmy says, a bit of potassium (which isn't a problem at all), but more of a conditioner, because we have such a high proportion of clay, and the ash helps to break it up a bit. Go for it!

The only problem with wood ash is it tends to be a bit alkaline so its not recommended for putting round raspberries or plants that need acid soil. Potassium is the nutrient that encourages flowers and fruit, but as Jimmy says its very soluble in water so no use for that purpose if spread in autumn and winter as it will all have washed away by spring. If you only want to grow lawn it won't matter at all.