Select a planting site for the Arum tubers before gathering them. Choose a planting site with similar light and moisture conditions as the parent plant. Avoid areas in full sun.
Spread a 3-inch-thick layer of compost and a 1-inch-thick layer of sand over the bed. Work the amendments into the soil to a depth of 5 inches using a soil cultivator. Water the bed to a depth of 4 inches.
Dig up the Arum parent plant once the new planting site is ready. Carefully insert a garden trowel into the soil 5 inches from the base of the Arum plant's foliage. Dig down to a depth of at least 6 inches. Lift the plant from the bed.
Manually remove the soil from around the Arum tubers. Locate the 2- to 3-inch-long side tubers. Gently detach the side tubers. Remove any foliage attached to the top.
Plant the Arum tubers in the prepared bed. Dig 4-inch-deep planting holes 12 to 15 inches apart. Settle the tubers horizontally in the planting holes. Cover the tubers with soil. Water them to a depth of 3 inches to settle the soil around them.
Water the Arum tubers whenever the soil dries out to a depth of 2 inches. Avoid letting the soil dry out until after the tubers establish themselves and send up foliage.
Watch for new foliage four to six weeks after planting the Arum tubers.