Papaver somniferum, better known as somniferum poppies or opium poppies, are annual flowering plants that boast an attractive, upright growing structure, greenish-blue foliage and rich red or orange blossoms. When planted outdoors, somniferum poppies grow best in United States Department of Agriculture (USDA) plant hardiness zones 8 through 10. Gardeners outside of these hardiness zones who care fortunate enough to have access to a greenhouse can successfully grow their own somniferum poppies with very little effort.
Choose a planting container for your greenhouse somniferum poppies that is at least 10-inches-deep and made of pressure-treated or rot-resistant wood. Make sure that the planting container you select has at least four 1/4 inch holes in the bottom to allow for adequate drainage. Arrange several sheets of newspaper in the bottom of your planting container. The newspaper will prevent the growing medium from washing out through the drainage holes with each watering.
Create a fertile, well-draining growing medium for your greenhouse somniferum poppies. Blend equal parts peat moss, potting compost and perlite to serve as the growing medium for your greenhouse poppies. Pour the growing medium into the prepared planting container, leaving at least 2 inches of space at the top of the container.
Mix one package of somniferum poppy seeds with a 1/2 cup of horticultural sand to make the seeds easier to distribute. Shake the poppy seed and sand mixture evenly over the surface of the growing medium in your prepared planting container.
Water your somniferum poppy seeds lightly to moisten the growing medium and encourage your seeds to germinate. Continue to water your greenhouse somniferum poppies as often as needed to keep the soil evenly moist, but not saturated.
Fertilize the poppies in your greenhouse once a month to promote healthy, vigorous growth. Feed your somniferum poppies with a balanced, water soluble fertilizer such as Blooms Plus, Miracle Grow or Grow More, applied according to label directions.