Put everything in a high-speed blender in the order listed. Blend on high until smooth and no spinach flecks remain, about 1 minute. Pour into 2 glasses and serve.
Notes
If you want to prep this the night before, put the grapes, celery, and spinach in your blender then put the covered blender in the fridge. The next morning, add the water, banana, frozen pineapple and ice cubes.
Recipe by Lemon & Mocha at http://www.lemonandmocha.com/2018/05/28/best-green-drink/