You can propagate a tulip poplar tree from cuttings or seeds.
Propagating from cuttings
In the fall, select a healthy branch that’s at least 18 inches long. Cut the branch just below a node, which is the small bump where new leaves or stems grow. Remove the lower leaves to prevent rot. Dip the cut end of the branch in rooting hormone. Fill a pot with potting soil. Insert the cut end of the branch about 8 inches into the soil. Cover the cutting with plastic to increase humidity. Place the pot in a protected area with indirect light. Check for roots after a few weeks. Transplant the tulip poplar into the ground in the spring after the last frost.
Propagating from seeds
Harvest the seeds in the fall after the seed pods have dropped from the tree.
Soak the seeds in water. Fill a pot with a well-draining seed-starting mix. Place the seeds in the pot and keep the soil moist. Provide the seeds with 12–16 hours of indirect sunlight or fluorescent light daily. Maintain a temperature between 65°F to 75°F (18°C to 24°C).
The preferred method for propagating a tulip poplar is from cuttings because the resulting plant is true to the parent tree.