From Ground: First, water the field briar to dampen the soil, which makes it easier to work with. Use a shovel or spade to dig a wide circle around the plant, being cautious not to cut into the root system. Gently work the shovel beneath the root ball, and pry the plant up with care to preserve the roots.
From Pot: Begin by watering the soil in the pot to make the root ball easier to remove. Turn the pot on its side, and tap the edges to loosen the soil. Gently pull the field briar out by tipping the pot over and supporting the plant with your hand. If the plant doesn't slide out easily, use a hand trowel to ease the soil away from the edges of the pot.
From Seedling Tray: Ensure the seedlings are well-watered before starting. Use a hand trowel or a specific seedling transplant tool to lift each field briar from its compartment, being careful not to damage the delicate roots and stem.