Poppies are desirable garden flowers because of their striking blooms and impressive height. These flowers can grow as tall as 60 cm (2 feet) and feature bright orange to red blossoms with ruffled edges. If you harvest the seeds properly, you'll be able to plant these flowers each year for free and have a crunchy supplement to your baked goods.
Poppies flower for several weeks after they mature, after which time the petals dry out and fall off of the central flower bulb. The bulb will swell and balloon out to about 2.5 cm (1 inch) in diameter. In most poppies, the seed bulb is green or green-grey. When the seeds are ready for harvest, the bulb will feel hard and dry and the flower's stem will become brown and brittle.
Paper bag harvest
Harvesting your seeds with a paper bag takes less time than other methods but requires very keen judgement. If you harvest too early with this method, your seeds may not be viable. If you harvest too late, the pods may already be open. When your poppy seed bulbs are totally mature and dry, but before they burst, break them off and place them in brown paper bags. Allow the bags to sit in a cool, dry place for about three weeks. Shake the bags sharply to release the seeds from the fully-dried pods and separate the pod pieces from the seeds.
Rag pouch harvest
Using individual pouches for each flower may take a lot of time, but you're certain to get a high yield of viable seeds. For this method, cut an 20 cm (8 inch) square of cotton cloth for each poppy. Tie one cloth around the seed bulb of each poppy, making sure that the knots are tight but the cloth is somewhat loose around the bulb. When the pods open, they'll release the seeds into the pouches rather than onto the ground. All you have to do is gently untie the pouches and gather the seeds.
Papaver somniferum is also called the opium poppy as its sap has narcotic properties when grown in some conditions. This poppy is also the only species to produce edible seed. It is legal to grow in the UK for ornamental and seed production purposes. It is illegal, of course, to make opium from the plant.