Growing Giant Pumpkins: A Beginner’s Guide to Growing Prize-Winning Pumpkins in Your Home Garden

Cinderella may have ridden to the ball in a pumpkin carriage, but today, growers of giant pumpkins are pushing the boundaries of what’s possible. These impressive pumpkins are reaching sizes that rival small cars. It’s no fairy tale – it’s the result of years of dedication and breeding.

The secret behind these giant pumpkins lies in the genetics. The most famous variety, the Atlantic Giant, originated from Howard Dill’s breeding efforts. Over three decades, Dill refined the genetics by crossbreeding various Mammoth pumpkin varieties. The result is a lineage that has produced truly massive pumpkins.

If you’ve ever dreamt of growing your own prize-winning pumpkin, this beginner’s guide will help you get started.

Genetics

For first-time growers, obtaining seeds of the Atlantic Giant variety is the first step. Numerous catalogs and garden centers offer these seeds, capable of producing pumpkins weighing over 400 pounds. However, to grow pumpkins that surpass half a ton, you’ll need superior genetics.

Experienced growers trade and sell seeds from their giant pumpkins. You can find these seeds on websites or from local growers. When browsing seeds online, you’ll come across information about the parent pumpkins from which the seed originated. For example:

  • 1050 Liggett 16
    • The weight in pounds of the pumpkin.
    • The surname of the grower.
    • The year it was grown (2016).
    • The female and male plants used for pollination.

Site Selection and Planting

Growing giant pumpkins requires ample space in your garden. Each plant needs approximately 1,000 square feet to accommodate its sprawling vines. Choose a sunny location with good surface drainage and access to water. These pumpkins require significant amounts of water to reach their maximum size.

Prepare the site in the fall before planting by incorporating organic matter like composted manure or leaf litter. This helps establish nutrient-rich soil. Some growers plant a cover crop in the fall, such as oats, annual rye, or clover, to further improve the soil’s organic content.

Fertilizer and Lime

Before planting, it’s advisable to conduct a soil test in the fall to determine if any adjustments in pH or soil amendments, like lime or macronutrients, are necessary. Always follow soil test recommendations when applying lime and fertilizers. Providing adequate nutrients throughout the growing season is crucial for healthy vines and larger pumpkins.

In the spring, apply granular fertilizers by broadcasting them over the soil surface and incorporating them into the soil. The recommended amount for giant pumpkin vines is approximately 2 pounds of nitrogen (N), 3 pounds of phosphorous (P2O2), and 6 pounds of potash (K2O) per 1,000 square feet of growing space.

After pollination and fruit set, start a foliar feeding or fertigation program using specialized foliar fertilizers. Follow the label directions and continue the application throughout the growing season.

Planting and Space Requirements

Growing giant pumpkins requires an early start. Sow individual seeds in 12-inch peat pots indoors around the end of April. Use a well-balanced potting medium. Transplant the seedlings when the first true leaf is fully expanded, usually 10 to 14 days after seeding. Protect the transplants from late spring frost using a floating row cover, cold frame, or small greenhouse.

Irrigation

Pumpkins have shallow roots, so ensure they receive at least 1 inch of water per week if rainfall is insufficient. During hot, windy days, they may require more water. Watering in the morning or early afternoon allows foliage to dry by evening, reducing the risk of leaf diseases. Trickle irrigation or soaker hoses are recommended, but overhead sprinklers can also work effectively.

Cultural Practices

If you properly prepare the planting bed, weeds shouldn’t be a major issue, especially once the vines cover the ground, shading out most weeds. Plastic mulches are highly effective for weed control and can also warm the soil and maintain moisture levels. Apply plastic mulch a few days to two to three weeks before planting. If you prefer organic mulches, apply them in the summer once the soil has warmed. For this type of mulch, additional nitrogen is recommended.

Hand weeding or hoeing can control any remaining weeds. Herbicides are an option, but their application should be performed by trained and licensed individuals.

Windbreaks

Windbreaks are necessary to protect young plants from strong winds until they become fully rooted. Position windbreaks on plants most susceptible to southwest winds until late June, when side-runners are 3 to 4 feet long. A snow fence and burlap can serve as an excellent windbreak. Additionally, covering vines at each node with soil will anchor them and encourage secondary root development.

Insects and Diseases

To reduce the risk of insect and disease problems, avoid planting in the same location for at least three years. Regular scouting and pest management programs are essential for successful pumpkin production. Striped cucumber beetles and aphids can transmit diseases, so keep an eye out for them. Squash bugs and squash vine borers are other pests that require monitoring and management.

Common pumpkin diseases include powdery mildew, bacterial leaf spot, and soil-borne diseases like Fusarium, Phytophthora, and Plectosporium. Follow the recommended pesticide applications and consider rotating products to reduce disease resistance.

Pollination

Although natural pollination by bees works well, some growers prefer hand pollination for more controlled genetic crosses. On the main vine, most fruit grows around 15 feet down from the root stump. Initially, allow only four to six pumpkins per plant. Once they reach the size of a volleyball, reduce the number to one pumpkin. This reduces competition for nutrients and increases the chances of achieving a giant-sized pumpkin.

Stem Stress

Due to the rapid growth and size of giant pumpkins, training the vines and root pruning is crucial. These practices prevent stem breakage and splitting. When the pumpkin reaches basketball size, curve the vine 80 to 90 degrees away from the fruit about 3 feet out. Then, curve it back towards its original direction. Clip the roots 3 feet out on the vine. This allows the vine to move upward as the pumpkin grows. If the pumpkin is long in shape, it may push the vine forward, resulting in a kink. In such cases, slide the pumpkin back about 4 to 5 inches, especially when it weighs around 300 pounds. Rotating round-shaped pumpkins without damaging the stem is challenging.

Shade

To protect pumpkins from direct sunlight, create a shade using burlap or lightweight material. Alternatively, drape a plain white bedsheet over the pumpkin, leaving the stem exposed. This prevents premature hardening of the skin and allows the pumpkin to achieve its full genetic potential in terms of size.

Harvesting and Moving Your Pumpkin

When the time comes to harvest and transport your pumpkin, several factors determine the technique you’ll use. Smaller pumpkins (under 400 pounds) can be moved with the help of friends and a heavy-duty tarp. For larger pumpkins approaching 700 pounds, specialized lifting frames and straps are necessary, typically used with skid loaders or front-end loaders.

Pumpkins with wider girth may require a trailer and secure straps for transportation.

Now that you have a beginner’s guide to growing prize-winning giant pumpkins, get ready to embark on an exciting gardening adventure. With patience, dedication, and the right techniques, you too can cultivate these incredible pumpkins in your own home garden!

References:

  • Homeowner’s Guide to Fungicides. University of Kentucky Fact Sheet PPFS-GEN-07.
  • Langevin, Don. (1993). How-To-Grow World Class Giant Pumpkins. Norton, MA: Annedawn Publishing.
  • Midwest Vegetable Production Guide for Commercial Growers. (2019) Ohio State University Bulletin 948. Purdue University.
  • Special thanks to Jim Jasinski, Extension Educator, OSU Extension, Champaign County, for his review and updates to the disease and insect portion of this fact sheet.
  • Original author: David Mangione, Pickaway County, Ohio State University Extension. (Originally published in 1994.)