If you ask 10 competitive pumpkin growers how to grow a giant pumpkin, you're likely to get 10 different answers. It seems everyone has his own way of coaxing the most weight out of these giants. But there is a thread of consistency that runs throughout all the instructions, and adhering to four basic tenets will get you well on your way. Above all else, you need good seed, good soil, hard work and good luck.
The Four Pillars
- GOOD SEED: If you want to grow a world-record pumpkin, you can forget about every variety of pumpkin out there except Howard Dill's patented Atlantic Giant. Since 1979, no other pumpkin variety has been a world champion.
- GOOD SOIL: Pumpkins are large consumers of all the major plant nutrients. A key for pumpkin growth is soil well amended with organic matter.
- HARD WORK: Proper care of your plant and pumpkin will greatly increase your chances of growing a big one.
- GOOD LUCK: If you can grow a good vegetable garden, you have the skill to grow a world-record pumpkin.
1. Preparing Soil
Start with a pH test in fall and adjust your pH to between 6.5 and 7.5 by adding sulfur to lower the pH or lime to raise it. Apply fresh manure in the fall. Apply compost or composted manure in the spring. Add 6 inches to 1 foot deep where you expect to plant. If you have a new garden area more is better than less.
2. Sowing Seeds
Start seed indoors in six-inch pots, 120-150 days before harvest. Round ½ gallon ice cream containers also work well. Cut the bottom off and turn upside down using the lid as the bottom. I recommend buying a high quality potting medium that can be purchased at your local nursery store. Plant the seed flat, ½ to 1 inch deep. Keep the soil temperature at 85 to 90 degrees F. Most seeds will emerge within five days.
3. Transplanting Seedlings
Transplant seedlings into the garden once the first true leaves appear usually seven to 10 days after germination. Handle with care because pumpkin plants are easily damaged during transplanting. The main vine usually grows the opposite direction of the first true leaf. If using an ice cream container, dig the planting hole, set in place, orient the plant, take the bottom off and then lift the contain up carefully past the plant.
4. Protecting Seedlings
Place a "mini-greenhouse" over the seedlings for six weeks to shield plants from wind and frost. These mini-greenhouses can be as simple as two storm windows nailed together to form a teepee or hoop house. A simple hoop house can be made from PVC pipe, rebar and plastic. Be careful on sunny days the temperature inside a hoop house can reach 100°. Making slits as vent or opening the sides helps cool things down on sunny days.
5. Training & Burying Vines
Train the main vine to run down the middle of your patch. Train side shoot, secondary vines, so they are perpendicular to the main vine to accommodate access to the vines and pumpkins. Pinch or cut off all other vines, tertiary vines, coming off the secondary vines. Bury the vines by placing a shovelful of dirt where each leaf meets the vine. Let each leaf grow above the vine before burying. Do not bury the vines where you see and plan on pollinating a female flower.
6. Bugs & Diseases
Contact a local grower or your local county extension. They can either be a huge problem or none at all depending on where you live.
7. Pollinating Flowers
Eight to 10 weeks after seed starting, the first female flowers will appear. A good female candidate should have a stem angle which is as close to 90° (perpendicular) as possible to the vine. You'll want to hand-pollinate the flowers. In the early morning, locate a freshly opened male flower. Pick it and remove the outer flower petals, exposing the stamen and fresh pollen. Locate a newly opened female flower and gently swab the stigma of the female flower with the pollen-laden stamen.
Getting a pumpkin set early, preferably before July 10-20th, is an important step. The earlier you set a pumpkin, the longer it has to grow until harvest.
8. Reposition Set Pumpkins
Once a pumpkin has set, its position on the vine becomes extremely important. Most often the stem does not grow at 90° to the vine. However, for optimal long-term growth, the best position is to have the stem perpendicular to the vine. When the pumpkin is about the size of a basketball you can slowly move the pumpkin perpendicular to the vine. This should be done in small steps over a period of a week or you will snap it off.
9. Select The Most Promising Pumpkin
If one plant has three strong vines, you could have as many as seven or eight pumpkins set and growing by July 20. Now you must choose the best pumpkin and remove most of the rest. Measure each pumpkin's circumference at the widest point weekly or daily. Choose the one that's growing fastest.
Before your pumpkin gets too large you will want to place it on something to protect it from rodents, potential rot from the bottom side and to keep the bottom side flat. Many growers use wood or ply wood with sand or landscape fabric on it.
Shade protection should be provided to prevent premature aging of your pumpkin. Build a mini-hoop house over your pumpkin carefully avoiding the vines.
10. Terminating Vines
Cut off and bury the end of the main vine when it has reached 10 to 12 feet beyond a set fruit. If you have a pumpkin on a vine that is 10 feet from the main root, cut the end of that vine once it is 20 to 24 feet long. Terminate the secondary vines when they are 8-12 ft long. Usually at the boundary of your patch. Bury them also.
11. Fertilizing
During the growing season, most fertility needs of pumpkins can be met by applying water-soluble plant foods once or twice a week over the entire plant area. Give seedlings a fertilizer that stresses phosphorus, such as 15-30-15. Shift to a more balanced formula, such as 20-20-20, once fruits are set. "Slow and easy wins the race."
12. Watering
Giant Pumpkins require approximately 1 to 1 ½ inches per week. The amount of water required can vary greatly depending on soil type, temperature, humidity, time of year, etc. Once you get a feel for your patch you can better adjust to your own watering needs.
13. Keeping Track
Measure your pumpkins at least weekly. Gains in circumference can average four to six inches in a 24 hour period. Measure the circumference of your pumpkins first parallel to the ground around the entire pumpkin, from blossom end to stem. Next, measure over the top in both directions: from ground to ground along the axis from stem to blossom end, then perpendicular to the stem-blossom-end axis. Add these together to obtain a, Over the Top, OTT measurement. Look up the OTT on OTT vs. Weight Table to find your estimated weight.