Pumpkin vines like warmth and seeds don't germinate in cold soil. Additionally, after germination, a late frost will damage seedlings. Three to four months of at least 75-degree daytime temperatures are needed to grow the plant. In the North, seeds are sown starting in late May, while in the Deep South, pumpkins can be planted through early July. Standard orange varieties can be harvested in 100 to 110 days--120 days for the gigantic varieties. Miniature pumpkins are ready in about 90 days.
Once seeds are buried about an inch deep in warm, moist soil, the conditions are right for seeds to develop. The outer layer of the seed, the seed coat, protects the nut within as it starts to grow. This nut will eventually become a new pumpkin. Since the seed coat is so tough, some gardeners like to soak the seed overnight before planting. Others even file the seed's sides. The seed first puts out tiny root hairs. Then it sprouts, bursting up through the soil in up to 10 days. The sprout quickly produces two small, rounded leaves.
About a week later, a different kind of leaf appears from the middle of the sprout, this one not having the smooth edges of the original leaves. After three of these types of leaves have established the plant, the plant has a growth spurt lasting a couple months.
Pumpkin plants drink deeply. They are "big eaters," too, needing a lot of nourishment. If you are generous, you'll be repaid with vigorous vines that sprawl out up to 30 feet. During their growth spurt, vines can grow several inches a day. Luckily, you can direct pumpkin vines to grow where you need them to, including up, since the vines have tendrils to grab on to things.
The vines can also be pruned. The plant produces both primary and secondary vines that tend to travel in opposite directions. Each produces tertiary vines; these are the vines to prune. Cut them as soon as they appear.
About two and a half months from when the seeds were planted, yellow flowers begin to appear. The vine produces both male and female flowers, the male flower providing the pollen--the female flower, after pollination, eventually producing fruit. Flowers start to bloom around dawn, ready for bees to service them. As the day wears on, flowers begins to close. Each shuts by the end of the day and does not bloom again.
A pumpkin will grow from a fertilized flower. To make it grow round, gardeners rotate it periodically. To keep it from rotting on wet ground, gardeners may place a board beneath it . As days get shorter, the vines begin to die as the pumpkin ripens. Once the shade had changed to orange or yellow-orange, depending on what variety the pumpkin is, gardeners cut it from the vine.