Open D Minor: D A D F A D
Open D Minor is simply a variation of Open D Major. The third string is lowered one tone from Open D Major, making it sound like a minor rather than a major.
Open D Major consists of D F# A, and Open D Minor consists of D F A emdash; all that needs to be done to get from Open D Major to Open D minor is to drop the F# to an F.
Like Open D Major, D minor is a very rich and resonant sounding tuning.
Getting into Open D Minor
I suggest first tuning to Open D Major, then simply lower the 3rd string one step to an F.
|Strings||Standard||D A D F A D||Changes|
|6||E||D||Lower 1 whole-step|
|3||G||F||Lower 1 whole-step|
|2||B||A||Lower 1 whole-step|
|1||E||D||Lower 1 whole-step|