Lapis
If I was relying on a powdered version of wheat grass, I would use Sweet Wheat.
Better than this is the flash frozen cubes grown in Eastern Canada by a producer who has eliminated mold in is product. Then the optimal way is to grow your own outdoors, utilizing Ocean Grown minerals. Grown this way, wheatgrass is a true super food. It is teaming with vital nutrients.
All produce that grew a century or more ago was highly mineralizing but our soil has become so very minerally deplete (on purpose) that most food is substandard for human/animal health. Add to that a mysriad of toxins added in the production of produce along the way from soil to market and you have poisonous food.
~Lapis~