How To Grow A Truly Giant Pumpkin

Pumpkin growing contests have sprouted up all over the country. Some are quite formalized and others less so (the weigh-in for my local contest is at a taphouse, after which celebrations are held). Growing huge pumpkins is a passion for many folks. With a manic obsession, giant pumpkin hobbyists hand pollinate, develop secret fertilizer recipes, and hoard seeds from previous orange orbs. 

But even if you don't go all out and top the world record of 2,749 pounds, growing a pumpkin so big you have to roll it out of the garden like Linus in It's The Great Pumpkin, Charlie Brown is a fun activity and worth neighborhood bragging rights. While growing a +1000-pound pumpkin takes practice and dedication, even beginners can achieve a 300-pound porch monster. 

Grab some seeds and start a new family competition–the loser has to do all the Thanksgiving dishes? Winner gets the last slice of pie? 

Choosing the Right Seeds

The variety to go with is Dill's Atlantic Giant. It's the monarch of the list and the most likely to give you a chance at an unliftable orange mega gourd. 

Howard Dill spent decades breeding and developing the Dill's Atlantic Giant variety, and it's the choice to get you up toward or north of that 400-pound mark. And, of course, aficionados keep seeds from their masterpieces, working up their own locally adapted plants to ever larger sizes.

Get a Head Start

Pumpkins are normally directly sown outdoors, and if you have a long growing season, that may be fine. However, many giant pumpkin growers prefer the more controlled conditions of starting their seeds indoors, babying the tiny plants for a couple of weeks, hardening them off, and planting them in custom-made spots. 

If starting your giant pumpkin seeds indoors, remember they grow quickly. A head start of only 2-3 weeks will be enough. If you have them indoors longer than 10 days, you'll likely need to pot them up into larger containers. 

• Soak your pumpkin seeds for an hour or two before planting, whether indoors or out in the garden, to speed up germination. 

• When starting pumpkins indoors, you'll need to provide supplemental lighting for 12-14 hours per day unless you have a greenhouse. 

• Remember that pumpkins, like other squashes, will not tolerate frost. Wait to transplant until you are sure the last frost of spring has passed. Look up your average last frost date and start watching the ten-day forecast. 

Sunshine, Good Soil, and Plenty of Nutrients

Pumpkins thrive in full sunshine, and when attempting to grow a giant, site selection is important. Choose a location with full morning sun and at least some afternoon rays. The site needs good drainage and not be prone to flooding or ponding after heavy rainfall. 

The vines can sprawl out quite a bit, so plan to allot at least a couple hundred square feet of space. While many people feel 600 or more square feet is required, truly huge pumpkins can be grown in an area of about 150 square feet (10 x 15 or even 6 x 25). 

Loamy and sandy soils are good candidates, but heavily compacted soils can limit rooting. But, for many of us, the soil we have is what we've got, so don't miss out just because your soil isn't perfect. Work in lots of compost and aged manure prior to planting. You can also try growing a couple giant pumpkin plants in raised beds for drainage and letting the vines roam around over the edges. 

Perhaps one of the most closely guarded secrets is each grower's unique method of fertilizing. The basics are N, P, and K, but many hobby growers of giant pumpkins will add mycorrhizal inoculants, adjust pH to a neutral 6.7-7.2, and create custom blends of micronutrients. If you talk to serious growers, they'll mention calcium, boron, and potions of ingredients to maximize every last bit of potential growth. But good loamy soil, plenty of water, compost, and regular weekly feeding with general-purpose fertilizer will still produce amazing results. 

Digging a Starter Hole and Planting

Whether transplanting or direct sowing, you'll want to loosen the soil deeper than a rototiller can reach to allow for faster rooting. Use a garden fork to loosen the soil as deeply as possible, working in your compost and providing a good starting base. 

If you are direct seeding, make a small hill and plant 3 seeds, each about an inch deep. Space the hills at least ten feet apart. Water the hills and watch for germination. 

For transplanting, prepare a hole in the freshly loosened soil and test fit the pumpkin prior to removing it from the pot. Look for the first true leaf (after the seed leaves). The main vine of the plant will form in the opposite direction as the first true leaf, so you can attempt to steer the direction your vines will spread.  Plant the young pumpkin with the first true leaf pointing away from where you'd like the bulk of the vines to grow. 

Provide Plenty of Water

Much of that pumpkin is water; if you haven't provided all it can use, the fruit size will suffer. While normal pumpkins need an inch of water a week, giants can use more during hot weather. If watering from overhead, do so in the morning so the foliage has time to dry before the cooler evening weather to minimize leaf fungal issues. Better yet, lay down soaker hoses or drip irrigation to provide targeted water at the root zone. Try to avoid dumping water directly on the crown of the plant where it comes out of the soil. Keeping that area soaked can lead to problems with fungi and root rots. 

For truly monster pumpkins, you may need to water daily, but as always, let the soil moisture tell you how often to water. Stick your finger into the soil and feel it–it should be damp and cool, not hot and dry. If the soil feels dry, it's time to water again. Allow the soil surface to dry slightly between waterings, and don't create a mudhole or a swamp. Remember, while the pumpkin needs a lot of water, the roots must still be able to breathe. Saturated soil may have a lot of water but not much oxygen. 

Pumpkins have shallow but broad root systems. If you see the plants wilting, it's likely they need water, but check the soil moisture before turning on the spigot.

Bury the Vines

This sounds crazy, but it's a trick of the pros. Pumpkin vines will root into the soil, and you can assist in this process for faster growth and bigger pumpkins. As the vine grows and you see the leaf nodes, bury the vine a couple of inches deep in loose soil. Keep going at each leaf node. Don't bury the terminal bud (the one at the growing tip of the vine), 

Look for the spot where a leaf stalk rises from the vine; that's the node. Once that leaf and stalk are well established, mound up a small hill 3-4 inches high around the node and water it. In time, the pumpkin will sprout roots there and increase your plant's root capacity, resulting in a bigger pumpkin. 

Pollination

While happy buzzing bees can pollinate your pumpkin patch quite effectively, you may wish to help out by hand pollinating. Nature is perfectly capable of achieving pollination, but for a giant pumpkin, you won't want to take any chances, as rain and cool, cloudy weather can reduce bee activity. 

Check out our post on hand pollination of flowers; the same technique can be used for pumpkins. If you hand-pollinate pumpkin flowers, do so in the morning.

Pumpkins produce both male and female flowers, and the male flowers often appear a week or two before the female flowers arrive. The female flower has a tiny fruit below it while the male flower does not. It looks like a miniature pumpkin, yellow and about the size of a golf ball. 

• Choose a male flower and gently remove the petals, leaving the reproductive parts in the center (the anthers) which are covered in yellow pollen. Take care to avoid knocking the pollen off before you get to the later steps.

• Find a healthy female flower.

• Rub the pollen-carrying parts of the male flower on each of the female flower's central structures (called the stigmas), being sure to get all around. Pretend you are brushing on BBQ sauce; don't miss any spots. 

• Alternatively, pollen can also be transferred with a small artist's paintbrush. Collect the pollen from the male flower (or several flowers) and brush it off on the female flower.

Culling Fruit and Pruning Vines

Pumpkin vines need a lot of space, and to harvest enough sunlight to develop a behemoth, you'll need to thin seedlings down after germination to reduce competition. Transplanted pumpkins, which are healthy and vigorous, can be planted at the proper spacing, but pumpkins sown directly in the garden may need to be thinned. 

After the second set of true leaves has emerged, choose the strongest, most vigorous vine to keep and snip the others in that location at ground level. Don't pull them, uprooting them could cause disturbance to the remaining plant.

If your goal is to have a porch full of beachball-sized orange globes, you can let the vines do what they will and leave several fruits on each plant. However, some vine training is helpful with these huge plants to keep the chaos limited. 

Many champion growers use the Christmas tree pattern, which could also be called a herringbone. Pumpkins have a primary vine (the big one coming from the ground) and then create secondary branches at a 90-degree angle off the primary vine. Eventually, the plant will keep spreading out, creating tertiary vines off the secondaries (similar to suckers on a tomato). For a massive pumpkin and to keep vines in check, prune off the tertiary vines and selectively snip secondaries so they alternate, going up the vine-like branches on a pine tree, allowing each vine room to spread leaves. Pruning vines is an advanced technique, and if you'd rather let the plant be and skip this chore, you'll still have huge pumpkins.

Once the fruits have set, it's time to start culling out the weak and choosing the best 1-2 pumpkins per vine. Look for young pumpkins that are well attached to a sturdy vine, forming well, and growing fast. Ideally, they are located in a spot with room to get larger–remember, a 400-lb pumpkin needs a lot of room to expand. 

Use pruning shears to remove the culls. You can wait until they are almost basketball-sized to make the decision and keep a spare for a bit longer than that, but remember that the more the plant's energy is divided, the less each individual pumpkin will grow. Let the vine put all its energy into one or two massive fruits for the biggest results.

The difference between a 150-pound pumpkin and a 1000-pounder (besides genetics) is in the care and attention you provide. Leave a variety like Dill's Atlantic Giant to do its thing with little input from you, and you'll have plenty of big 80 and 100-pounders with an occasional larger one. Provide just a little extra TLC as above, and you'll be rolling that orange globe out of the garden instead of carrying it.