Spread the Nicotiana quadrivalvis leaves over a flat surface. Cut away the thick stems with scissors and discard them.
Moisten six sheets of cheesecloth. Do not saturate them since this may cause the leaves to mold.
Place a single layer of leaves between sheets of moistened cheesecloth. Repeat this step until all the leaves are between layers of cheesecloth, creating a stack.
Store the leaves in a cool place out of direct sunlight until the cheesecloth is dry. Lightly mist the cheesecloth periodically to remoisten it. Continue this for two weeks until the leaves are cured and dry, at which point they can be crushed or powdered for use.
Harvest whole Nicotiana quadrivalvis plants. Clip off the flower heads, if present.
Hang the whole plants on a laundry drying rack with the leaves pointed toward the floor.
Dry the plants for one week in a cool, dry place away from direct sunlight. If the climate in your area is especially moist or cold, dry the plants for up to three weeks.
Clip away any thick stems and store the leaves in a paper bag until ready to use.
Preheat your oven to 150 degrees Fahrenheit.
Place a single layer of Nicotiana quadrivalvis leaves on a baking sheet and lightly mist them with water.
Place the baking sheet in the oven, leaving the door open a crack. Prop the oven door open with a wooden spoon, if needed.
Dry the leaves in the oven on a low heat for 10 hours, periodically misting them with water.
Store the leaves in a paper bag away from moisture, light and heat until ready to use.