How Do Pumpkin Seeds Grow?

The Versatile Pumpkin Seed

Pumpkin seeds guarantee the survival of the species for the annual squash called the pumpkin. Pumpkins are grown around the world for their nutritious flesh, and their seeds are also valued as food. Spicy "pepitas" and salted pumpkin seeds are tasty morsels, full of nourishing vitamins and proteins. Roasted, salted or boiled, they are enjoyed by children and adults. It's fortunate that so many seeds are produced in one pumpkin. Each seed can grow a new pumpkin seedling, ready to take root in the right place and grow to 30 feet in length, producing a dozen or more pumpkins and thousands of new seeds.

Seed Formation

The first flowers of the pumpkin vine are male. They are followed by the female flowers, which each bloom for just one day. Birds and bees do the pollinating and baby seeds form in clusters on the ends of stamens as the female flowers are fertilized. The female flowers then collapse, forming a papery globe that will grow thick and form the pumpkin. The seeds mature as the pumpkin forms until each contains the embryo of a complete pumpkin plant. As the pumpkin grows, the seeds stick to the inside of the strands of flesh where they can be harvested by pie-makers or Jack-O-Lantern artists. Left to itself, the squash rots in the field and the ripened white, black or striped seeds are freed from the confines of the pumpkin, packed with cells containing DNA and food to keep the embryo over the winter. Since pumpkins are a favorite food of deer and small animals, the seeds can also travel to a new location in the digestive system of a larger animal --- smaller animals tend to chew up the seeds, destroying them.

Germination

Pumpkin seeds germinate best in warm, well-drained, fertile soil when the spring rains provide plenty of water. The husk softens in the dampness and the shell breaks as the embryo begins to grow. First, a "radicle" emerges downward to search for water and nutrients in the ground and then the "plumule" carries the seed case upward, growing toward the warm surface and the sun. As with other dicots, pumpkins sprout two leaves as the plumule breaks the surface, discarding the seed case. Then the seedling begins producing its own food supply by converting sunshine to chlorophyll, circulating it throughout the seedling and converting nitrogen and other nutrients gathered by the little radicle. When the radicle grows and begins splitting into a root system and the "true," or adult, leaves start forming on the stem, the pumpkin seed's job is complete and a new generation of plants has begun.

Resources

• Germinating Pumpkin Seeds
• Growing Pumpkins
• University of Illinois Pumpkins and More