Have you ever tried to juice wheatgrass in a high-speed, spinning, centrifugal juicer? If you have, you know the results are horrible. You get a big pulpy mess and very little juice. The best thing to use is a masticating juicer. These machines use grinding gears to efficiently extract the most juice possible from leafy greens like spinach and wheatgrass. I found some really fantastic masticating juicers.