Pumpkin seeds are a highly nutritious source of Vitamins A and B, as well as calcium, phosphorus and essential fatty acids. Pumpkins are in the Cucurbitacae family, which also includes squashes, cucumbers and melon. All Cucurbitacae seeds are edible, but those from pumpkins are larger and easier to harvest and process. Even the seeds from a Jack o' lantern can be separated from the soft insides and roasted with spices for a nutty-tasting, healthy snack. Some pumpkins produce more seeds than others, and some produce seeds that are easier to prepare for eating.
All pumpkins produce seeds, but Cucurbita pepo (the species that includes Jack o' lanterns) produce the most seeds. C. pepo cultivars from the Styrian region of Central Europe are used most commonly in large-scale seed and oil production. This is because Styrian varieties have more bountiful seeds with underdeveloped shells, called "hull-less" or "naked" seeds. The lack of a hard shell makes them easier to open and remove the nutritious green seed from inside. Some common Styrian varieties include Lady Godiva, Snackjack and Eat-All. Cultivars that produce smaller fruits like 'Kakai' tend to have more seeds than large-fruit varieties.
Transplanting and Maturation
Pumpkins are warm season crops that can take up to 120 days to mature. They require soil temperatures of at least 65 degrees to germinate and grow. For most regions, it is necessary to start the seeds indoors, then transplant them outside when soil temperatures are warm enough and the seedlings have developed their first set of true leaves. In a 2007 Slovenian study on seed oil pumpkins, researchers found that the plants grown from greenhouse seedlings had consistently higher fruit and seed yields. Additionally, only mature pumpkins have a full set of well-developed seeds, and transplanting gives them a chance to ripen before the cold weather sets in.
Pumpkin plants have both male and female flowers, with fruit developing only from the females that have been fertilized. The more prolific male flowers open first and stay open for a day, then the females open for a day. This short period when males and females are open at the same time makes a limited window during which pollination is possible. Some farmers place beehives near pumpkin patches to encourage pollination, and you can help garden pumpkins become fertilized by refraining from using insecticides when the flowers are open. For a more scientific approach, try collecting pollen from the thin, dusty stamens of male flowers with a paint brush, then paint the pollen onto the moist pistils of the females.
Other Cultivation Factors
Pumpkins are prone to several different types of fungus and mold as well as insect damage because they stay in the field for so long, which can severely affect seed production. Weeds can also rob the plants of essential nutrients. To give your pumpkins the best chance of maturing fully and developing seeds, only plant them in a place pumpkins haven't grown for the last several years to reduce disease and insect damage. In the fall, mix aged compost or well-rotted manure in the soil to enrich it. Water the plants regularly every five to seven days, and check them daily for insects.