Article from P.Allen Smith, photos are mine.
I confess that I am obsessed with pumpkins. Whether it is a bowl of mini-pumpkins on a table, a stack of cushaws, luminas and blue hubbards by the front door, or a traditional Jack-o-lantern, there is no easier way to decorate for the season.
Growing pumpkins takes a lot of space, but if you've got it I recommend giving them a try.
Pumpkin plants like warm soil so set out plants about two weeks after the last frost date when the ground has had a chance to warm. The soil also needs to be fertile. Amend the planting area with a generous amount of compost or well-rotted manure. Unless your soil is nitrogen poor, don't add nitrogen. Too much of this nutrient will result in lots of leaves, but few flowers. Space plants feet apart or place one plant per hill. Make hills about three feet in diameter and six inches high.
Water early in the day and low to the ground using a soaker hose or drip irrigation. This will help keep the foliage dry and prevent fungal diseases like powdery mildew.
Pumpkins bear both male and female flowers. The female flowers are easy to identify by looking for a tiny fruit below the blossoms. Male flowers are borne atop a bare stem and often drop to the ground as they wilt. Bees and other small insects pay numerous visits, spreading pollen from the male flowers to the female flowers.
Pumpkins mature in 3 to 4 months, depending on the variety. A pumpkin is ready to harvest when it has reached the desired color and the rind is hard. You can test its readiness by jabbing your fingernail against the outer skin, or rind. It should be strong enough to resist puncture. Also, you can tell a pumpkin is ripe if you hear a hollow sound when you thump it.
Collect your pumpkins before the first frost or when night temperatures are expected to drop down into the 40s for an extended period of time.
Gently clean the pumpkins by brushing off any excess dirt and then place them in a dry, warm area for 7 to 10 days. This will heal scratches and further harden the rind, which helps reduce moisture loss. If a frost is expected, cover the pumpkins with a frost blanket overnight.
After they have been cured keep your pumpkins in a cool location (about 50 to 60 degrees F), out of direct sunlight with plenty of good air circulation. Stored this way, they should last up to 3 months.
Good to Know: Pollination
Lack of pollination is one reason pumpkin vines don't produce fruit. There are several reasons why pollination does not occur. Environmental conditions such as unusually hot or cool temperatures, excessive moisture or low light will reduce successful pollination.
Honeybees and other pollinating insects are invaluable helpers in the pollination process. If you use floating row covers, harsh insecticides or even organic insect repellents you reduce the ability of these garden helpers to get their job done.
If you are using floating rows covers to protect your plants from harmful insects, remove them when female flowers begin to appear. Repellents such as garlic spray should be applied a few days before the flowers open. And only spot use insecticides for problem areas.
You can also hand pollinate female flowers. Using a small paintbrush or cotton swab, collect the pollen from a male flower and transfer it to the top center of a female flower.