Wheatgrass grown in the ground might be a little more nutritious because it has grown a little longer and has had time to pick up more nutrients. But this is only for a short window of time. Remember, Wheatgrass is young wheat trying to grow up and be large stalks of wheat, which is where we get our grain. If a company is harvesting one time a year and drying or freezing the wheatgrass juice, this is true. If you want fresh wheatgrass year round, then the only option is to grow it in trays.