Remove the seedling from its container carefully. Avoid manipulating the roots more than necessary. If the plant is in a peat or fiber pot, you can plant the seedling in its pot. Tear off the upper rim of a fiber pot so that it won't be exposed above ground.
Dig a hole as deep as the seedling's pot. Allow room to accommodate the taproot without bending or crowding.
Place the plant in the center of the hole and fill in around the sides with soil. Press down gently as you go to remove air pockets. Plant additional seedlings 10 inches apart.
Water gently with enough water to saturate the root zone.
Clip out individual leaves with scissors or pinch them between your finger and thumbnail. Cut at a point close to the main stem.
Cut the main stems close to the ground once the flowers are fully mature.
Fasten the stems together near the base with a rubber band or tie them with string.
Hang the bundles upside down over a tray to dry. As the flowers dry, the seeds will fall into the tray.