From Ground: First, water the dahlia 'Purple Gem' plant to dampen the soil. Then, dig a wide trench around the plant using a shovel or spade, ensuring the plant's root ball remains intact. Carefully work the spade under the root ball to lift the plant from its original location.
From Pot: Water the dahlia 'Purple Gem' plant thoroughly. Gently knock on the sides of the pot to loosen the soil. Carefully tip the pot, supporting the plant at the base, and slide it out. If the plant is root-bound, gently tease the roots apart.
From Seedling Tray: Water the dahlia 'Purple Gem' seedlings and use a trowel or your fingers to carefully lift each seedling with its soil intact. Handle the seedlings by their leaves to avoid damaging the delicate stems.