How to Grow a Giant Pumpkin Guide

Growing award-winning giant pumpkins is a sport. Giant pumpkin growers are as dedicated to their growth as athletes are to their sports. It is a world of its own! The current pumpkin world record holder is Stefano Cutrupi from Italy. His pumpkin weighed in at a whopping 2,702 lb 13.9 oz in fall 2021. Award-winning giant pumpkin growers do it for the challenge to “go big or go home”. They push the limits of pumpkin growing, always trying to outdo or out-smart their fellow giant pumpkin growers. Along with bragging rights, winners can also bring in big returns winning upwards of $9/lb per pumpkin. Additionally, award-winning pumpkin seeds can sell for $100 each!

How to Grow a Giant Pumpkin: A Step-By Step Guide

What does it take to grow a giant pumpkin? Some watchful care, pruning, feeding, and encouragement. Some good genetics won’t hurt either. Here we are going to walk you through the process of growing a giant pumpkin in your very own home garden. For a peek at our growing efforts check out "The Story of Our Giant Pumpkin".

Step One: Prepare your growing space

Giant pumpkin growers recommend preparing your growing area and testing the soil in the fall. Pumpkins do best in soil that is slightly acidic to neutral around 6.5-6.8 pH. Make any amendments needed for the soil. Adding as much organic matter to your soil as possible is important because giant pumpkins are giant eaters. Amending your soil and preparing the grow space in the fall means your soil will be fueled with better organic soil conditions when it is time to plant in the spring. Your pumpkin will need 8-12+ hours of sunlight per day with lots of growing space to spread out. A large area (1000 sq ft or 40 ft diameter for award-winning pumpkins) is recommended.

Step Two: Select Your Seeds

Selecting good pumpkin seeds matter. Because much of a pumpkins size is determined by its genetics you need to choose a seed that corresponds to your desired size. Most award winners originated from the Atlantic Giant pumpkin variety. People who are serious about pumpkin competitions buy and sell individual pumpkin seeds with winning genetics for some lofty prices compared to the average garden seed. If you are just trying to grow a large pumpkin to display, the Dills Atlantic Giant or Big Max varieties are excellent choices. Generally pumpkins take about 120 days to mature.

• Unique Competition Seeds - If you are chasing after more unique competition seeds, you can understand quite a lot from their names. Grower-sold giant pumpkin seeds will be listed with their weight, the growers name, the year it was grown, and sometimes its parental cross. Ohio State University explains this format of seed identification on their pumpkin growing factsheet. The saved seed of a 1050 lb pumpkin grown by someone by the last name Liggett in 2016 would be listed as 1050 Liggett 16, followed by the parental cross 1016 Reeb X 1901 Larsen.

Step Three: Start Your Seeds Early

Start your pumpkin indoors and follow the seed sowing instructions. To allow the maximum amount of growing time you want to get your starts outside as soon as possible, without exposing them to freezing temperatures. Usually this means germinating and planting your seeds 2-3 weeks before your last spring frost date.

• Germinating Giant Pumpkin Seeds - If you have paid the premium price for some quality seeds you sure don’t want to waste them. To aid in their germination you can utilize the scarification technique of filing the seeds edges to increase water absorption and speed germination times. Gently file the edges except for the pointed tip where the roots will grow from. File just until you can see a change in color as the outer seed coat is removed. Then soak the seeds in warm water for 3-6 hours. You can soak for as little as two hours and up to 24 hours depending on your preferences and how hard the seed coat is. If you are following the above recommended scarification practice though we recommend sticking to a shorter soak time. Then, wrap your seeds in a damp paper towel until they have sprouted.

Once your seeds have germinated it is time to plant them in a pot. Sow your seed ½ inch deep in a pot up to 12 inches. Keep the soil moist, not wet. You will see the best germination and growth around 85 to 90°F by using bottom heat. When the sprout emerges place under a light (only inches away from the plant) or near a window with full sun. For a more specific timeline and growing tips contact your local Pumpkin Growers Association.

Step Four: Plant Outside ASAP

You can transplant your pumpkin start as soon as you have passed your last spring frost date. Find your frost date from a trusted database to plan your garden. Pumpkins do not like being in a pot for long as their root systems can grow quickly. When planting add organic matter, such as compost, to the soil for good drainage and a source of nutrients. Pumpkins need a lot of water to thrive. Water daily, or as little as every 2-5 days depending on soil moisture levels and local soil conditions. It is best to water at ground level, avoiding wet leaves to prevent disease. When dealing with cool temperatures it is best to cover with a row cover or plastic sheet to maintain stable temperatures. Pumpkins like warm weather for better plant development. If temperatures within your cover begin to approach 85°F, ventilate to prevent stunted growth.

Step Five: Giant Pumpkin Pollination

While pumpkins are traditionally pollinated by bees, a more precise method is used to grow extremely large pumpkins. To guarante desired development, select a female and male flower to manually pollinate. The male flowers will be more plentiful with long stems. The female blooms, while fewer than the male, will have an obvious difference. At the base of the flower there will be a swollen ovary. To allow enough nutrients to be directed to your developing pumpkin select a bloom on the main stem with several secondary vines growing behind the bloom. You will want to remove secondary vines developing on the main vine, after the fruit as it grows. Paint the pollen on the anthers from your selected male flower onto the center of the female flower. To prevent the possiblility of cross pollination you can use a cover or ziptie to keep the blooms closed before and after pollination. Pollination should take place around the end of June/Start of July.

Step Six: Control the Vines

Only allow a single pumpkin to grow per vine so that all the nutrients and growth hormones are focused on its development. If you are worried something may happen to this fruit you can allow a second fruit to grow for a short time in case something happens to the first. Cut off any extra flowers or pumpkins on the vine. Managing new vine growth is the most important ongoing task in growing a sizeable pumpkin. Allowing multiple flowers and fruit to develop causes the nutrients and hormones to be split, resulting in more pumpkins of smaller size. To push the optimum amount of nutrients into developing one giant fruit, prune your vines as they grows

• Pruning Pumpkin Vines - Once secondary vines, before the developing fruit, reach 15 feet long cut their tips. Remove all secondary vines after the fruit/selected bloom. To encourage better water uptake it is best to bury the vines allowing them to push more root development between the plants base and the pumpkin. Do not bury the leaves. The closer you get to the fruit allow the vine to remain loose. As the pumpkin grows it will need more flexibility allowed in the vine to prevent breakage. Many grower recomend directing the vine to grow in an L or U shape to deliver nutrients, but reduce the opportunity for the vine to break. To help direct the vines growth you can dig a small trench or furrow, also making it easier to cover the vine with soil.

Step Seven: Fertilize Regularly

Because these large pumpkins are heavy feeders it is important to fertilize every 5-10 days after pollination has occured. According to Ohio State University, “Giant pumpkin vines require approximately 2 pounds nitrogen (N), 3 pounds phosphorous (P2O2) and 6 pounds potash (K2O) per 1,000 square feet of growing space.” To know how much of this should be applied as a fertilizer we recommend testing your soil. Application rates and fertilizer types are often perfected through personal experience and preferences. Applying too much of any nutrient at one time can cause adverse affects on growth. This is why we recommend soil testing for a more complete picture of your soil profile.

Step Eight: Think Ahead, How Will You Move it?

Once these fruits develop over 25 lbs it can be incredibly difficult to move these giants. To make it easier on yourself, we recommend creating a plan for how you will move it when you are ready to harvest. Just as a grower will likely have personal preferences for how to prune, fertilize, and protect their developing giant pumpkin, they will likely have a preference on what is best for moving it. One option is to place a wooden pallet under the pumpkin when the pumpkin is 25 lbs or less. Once established, if given adequate water, sunlight, and nutrients, giant pumpkins grow quickly. They sometimes put on as much as 50 lbs per day! Of course that depends on the growing conditions, genetics, and location.

Step Nine: Protect and Harvest

Until you are ready to harvest your pumpkin, keep a watchful eye. If you live in an area with intense sunlight, you may want to shade your pumpkin. This can prevent sun scalded skin and overheating. These conditions can lead to premature ripening and reduced growth. We wish you the best in your pumpkin growing efforts, displays, and competitions.

Growing giant pumpkins is a fun experience for kids, and you can almost see the pumpkins grow towards the end because they grow so fast. If you don’t have the space to grow your own giant pumpkin, you can always help us enjoy ours by joining us at the Annual Ginormous Pumpkin Regatta. Each year we partner with LiveDaybreak to put on this great event where pumpkin growers turn their giant pumpkins into great floating boats. Enjoy the fun October 8th 2022 10 am - 12:30 pm as teams race around the Oquirrh Lake through an obstacle course. Join us for some eppic races, games, petting zoo, and more! Perhaps we’ll see some of you and your giant pumpkins there!

Good luck!

Other Contributing Authors:

Erica Groneman, True Leaf Market Writer