So you want to grow the biggest, baddest pumpkin on the block. You want a sumo pumpkin. A pumpking. With the right conditions, the right seed, and a dose of luck, you can grow a pumpkin that makes other pumpkins look wimpy by comparison. Here are some tips.
Pumpkins love lots of sun, rich soil, plenty of plant food and water. Prepare your soil by mixing a 3-inch thick layer of garden soil, such as Miracle-Gro® Garden Soil for Vegetables and Herbs into the top 6 inches of soil. Once you've prepared the soil, you're ready to plant.
For big pumpkins, many experts recommend varieties such as 'Atlantic Giant' and 'Prizewinner'. Simply plant 2-3 seeds several inches apart in a cluster. Tamp them down so the seeds are making good contact with the soil, and cover them with another thin layer of soil. Then water gently. You can plant pumpkins after the last frost, but if you're going big, either start them indoors four weeks before the last frost in a seed starting mix, such as Miracle-Gro® Seed Starting Potting Mix. Once your pumpkin seedlings have grown 3 leaves, remove all the scrawny weaklings and coddle your biggest. After you transplant the seedlings, cover the plant outdoors with a cloche (a glass covering designed to extend the growing season) or portable cold frame to protect it from wind and frost. The idea is to keep your plant nice and warm and living in daytime temperatures above 75 degrees for 3 or 4 months.
Hand pollinate your pumpkins to ensure they start fruiting faster. Male and female flowers are easily distinguishable: male flowers will appear first, and female flowers will grow a small bulge of fruit between the blossom and the vine (the males grow on slender stems). As soon as a female blossom opens, pick a male flower and strip it of petals, leaving the pollen-bearing stamen. Wipe the stamen against the segmented stigma of the female flower. Be sure to transfer pollen to all three segments. Congratulations - you've done the work of the birds and bees.
When you see fruits develop to about 4-6 inches in diameter, remove all but the one that has the best shape. Keep pinching back flowers and vines to force the plant to direct all its energy to your prize pumpkin. Place cardboard or plywood under the fruit to keep insects in the soil from burrowing in.
Any good sumo wrestler eats an enormous amount of food to put on weight. The same is true with your sumo pumpkin. Feed your pumpkin plant every 2 weeks with a water-soluble plant food, such as Miracle-Gro® Water Soluble All Purpose Plant Food, or for easy feeding use Miracle-Gro® LiquaFeed® Tomato, Fruits & Vegetables Plant Food.
Pumpkins are thirsty, and big pumpkins are even more so, but you can easily over-water. Be sure to keep the soil moist, but not wet. Water whenever the soil feels dry to the touch. With enough moisture and nutrition, giant pumpkins can grow over 30 pounds in a single day.
Your big pumpkin might start to flatten a little, so you want to distribute its weight. You can do that by carefully rolling the fruit about every week or so. Move them gently. Gradually reposition the pumpkin so it grows at a ninety degree angle to the main vine. Pests will want a piece of your pumpkin. Plant companion plants like onion, leeks or dill nearby and combat them naturally.
Check to make sure the stem has become woody, then cut it from the main vine with a sharp knife, leaving several inches attached to the pumpkin. Depending on the variety you planted, pumpkins mature between 95-110 days after planting. If you can, try to not to harvest pumpkins until the vine dies.