Tom J. Bechman TOO DEEP? Agco Fendt Momentum Crop Tour plots in 2020 showed that a 3-inch seeding depth didn’t cost yield, but 3.5 inches did. The sweet spot is usually around 2 inches deep, experts say. Test plots offer insight into the age-old question of how deep to plant corn. How deep should you plant corn this spring? It’s an age-old question. Your grandfather or great-grandfather stewed over it when he planted check-row corn with a two-row planter pulled by horses. You still face the same decision today, even if your planter is equipped with technology that can put seed exactly where you want it, and even adjust on the fly to make sure seed stays in moisture. You must still make decisions and set parameters on how shallow or deep you’re willing to plant.