Pumpkins, with their edible flesh and long storage life are a warm season crop. They require a long growing season of nearly 85 days, so it’s best to start them indoors from seed. About a week after the last frost (on average May 15 along the northern Colorado front range), pumpkins can be planted outdoors. But be careful, pumpkins do not like their roots disturbed. We recommend starting them in a natural peat-pot (offered in the garden shop) that can be planted directly in the soil.
Choose an area in your garden or yard that receives plenty of sunlight, and has at least 8 ft. x 8 ft. for pumpkin vines to spread. Soil should be rich with organic matter, but not over-fertilized, which can stunt fruit growth.
Pumpkins will start to develop after blossoms are pollinated, so encourage pollinators to visit your garden with other flowering plants. Also avoid using pesticides in and around your garden, since also harm beneficial insects as well as pests.
To increase the size of giant pumpkins, pick a few nice-sized fruits and cut back the vine just beyond them. This will help all the resources of the plant to be devoted to the growth of those remaining pumpkins.
Interested in entering our annual Giant Pumpkin Contest? See our Calendar of Events and check the month of October for the exact date. Get growing!
- Backyard Boss
- Big Pumpkins
- Old Farmer’s Almanac: Pumpkins
- PlantTalk Colorado – Growing Great Pumpkins
- Rocky Mountain Giant Vegetable Growers
- You Tube: Larry Checkon, the world record holder for the largest pumpkin
Originally published on August 3rd, 2014. Updated on January 20th, 2020.