Giant pumpkins provide a staple for county fairs and newspaper feature photos each fall. To grow your own Cinderella's coach or the world's largest jack-o'-lantern, start with a variety bred to grow big. Know that oversize pumpkins make a great show, but don't plan on turning your giant specimen into pumpkin pies. Big pumpkins don't produce that much flesh, and what flesh it does have may be stringy or tough. Fans of roasted pumpkin seeds are in luck, however, since the larger the pumpkin the more seeds it will produce.
Plant a giant variety of pumpkin such as Atlantic Giant or Mammoth Gold. These pumpkins are bred to yield fruits weighing from 50 to 100 pounds.
Sow seeds directly in the garden as soon as danger of frost has passed. Giant pumpkins need at least 120 days to mature.
Remove all but one or two of the largest plants once seedlings mature.
Pinch off the first three female flowers when the plant starts to bloom. A female flower has a small bulb at the base which will develop into the fruit. Removing these early flowers allows the pumpkin vine to grow stronger before setting fruit.
Choose one fruit per plant to nurture as your giant pumpkin. Pick off the rest of the female flowers once your chosen fruit starts to develop.
Water the pumpkins thoroughly at least once a week. Pumpkins need lots of water to develop fruit, but they don't like to sit in water. Let the water soak in slowly over an hour or more.
Fertilize once a week with a complete fertilizer for vegetables.
Mulch with straw, shredded paper, newspaper or grass clippings to conserve water and to keep the developing pumpkin clean and out of the mud.