Ashes in Garden
Can I put ashes from plant burning (potato tops, daisy stems) in my garden?
Certified GKH Gardening Expert
I would put it into your compost pile first, just so some of the salts and plant unfriendly chemicals in ash have some time to get leeched away.
You can put it directly on the soil and you probably will not be adding enough so that it would harm your living plants, but it is better safe than sorry.