Is the ash burning black, or grey/white?
If it's burning black, the plants the bud came from probably weren't given the clean water run in sufficient time before harvest, if at all. This could be what is making it harsh, if it's black ash.
If it's black ash, then a water cure could solve this problem for you. It will take around 3 days of your cannabis matter fully submerged under water, changing the water daily but it is worth it if you can wait and want a smoooth smoke.