I use wood ash regularly..but as Robert says..a bit later on..
I use it bit like fish-blood-bone meal..a good handful or so around square meter measure.
But it is easier to spread if you mix it with bit of compost..so you can chuck it about and wind will not blow it away or on your face :-X
I spring feed my fruit bushes in February with mixture of equal amounts of BFB, wood ash, compost...