You could try this tool from hate5six: http://hate5six.com/sage - historically, they've only worked with hardcore / metal music, but this appears to be a new tool which expanded out to 200k artists across all types. I managed to find 3 folk artists which I am loving, and had never heard of from either Google or spotify. Curious if it is broad enough to work for your taste in music.

(not affiliated with them in any way)