From Ground: First, water the grass-leaved iris plant to dampen the soil. Then, use a spade or shovel to dig a wide circle around the plant, ensuring you're deep enough to keep the plant's root ball intact. Carefully work the spade under the root ball to lift the plant from its original location.
From Pot: Gently squeeze the sides of the pot to loosen the soil. Turn the pot sideways and, while supporting the base of grass-leaved iris with your hand, gently slide it out of the pot. Be careful not to yank or pull on the stem.
From Seedling Tray: Water the seedlings well. Grasp the grass-leaved iris seedling gently by its leaves, not its stem, and pull up very gently. If the seedling doesn't lift easily, use a butter knife or seedling dibber to ease it out of the cell, taking care to lift the entire root ball along with the seedling.