How much space should you leave between your plants and the wall, and why is it necessary? The answer is simple: airflow. In order to achieve maximum airflow, there needs to be space for the air to circulate. When plants are lined up to the wall, air cannot flow freely through to every plant and they get weak. When plants have freedom to move around, they grow stronger and you, the grower, will find it easier to move around and enjoy your time tending your plants.