A prickly pear is a type of cactus that develops by growing pads. After about three years of growth they will develop flowers. Growing prickly pear cactus from seeds is possible but an easier way is by cutting off a pad and transplanting. You need to remember this type of cactus is native to an arid desert environment with a lot of direct or filtered sunlight but can survive in a partially shaded location.
To grow a prickly pear from seeds use a seeding tray filled with a cactus mix or a combination of sand and pumice. Seeds need light to germinate so sprinkle the seeds over the seeding mix and just press lightly onto the soil to anchor with the bottom of a glass or jar. A light dusting of sand over the top can be added. Keep the soil damp but not wet. The seeds should produce a seedling in a few weeks. Allow the seedlings to develop before transplanting. It can take a year for the seedling do harden so it is best to first transplant into a pot and allow it to develop before moving it to an outside garden. Once the plant has developed, it is best allow the soil to dry before watering.