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A guide to growing your own giant pumpkins

A guide to growing your own giant pumpkins


Preparing the patch

Your patch should be in an area that receives full sun or as much sun as possible.

For each plant you intend to grow, you will need a minimum of 400 square feet of area, with the ideal size being 600 -700 square feet. A plot 25 feet by 25 feet is 625 square feet, the perfect size.

Of course, a pumpkin can be grown in any available area, a small flower bed or garden. Yet for these beasts to grow truly large, size matters.

Soil condition is perhaps the most important ingredient in growing a giant pumpkin.

When starting a new patch in which to grow giant pumpkins, haul in and spread at least a couple loads of manure, preferably aged or composted. Aged compost is an excellent amendment that can be added in the fall or spring. Amendments to adjust your soil PH toward an optimum reading of 7.0 should be added in the fall. Add lime if your soil test shows your PH to be low. Agricultural sulfur can be added if your PH is high.

Early in spring, as soon as your soil is dry enough to work, and your amendments have been added, till your soil. Never try to work your soil when it is too wet, as you will do more harm than good.

After your patch is tilled, erect a small hoop house or cold frame over the area where your seedling will be planted. The purpose of this mini-greenhouse is two-fold: Your plant needs the ground to be warm before planting, and your plant will need to be protected from cold weather on those early spring nights.

The enclosure should be large enough for the plant to grow inside for up to three weeks so a 3’ x 3’ area should be the minimum area it covers. Remember, if you keep the top of the enclosure fairly low to the ground, you will retain more of the days’ heat after dark.

The fall is the best time to add amendments to your soil. General practice is to add soil amendments such as manure, compost, leaves, lime or sulfur and any fertilizers that don’t leach out quickly in the fall.

Starting the seeds

Seeds should be started inside on or about the last week of April, depending on the weather. Use a 4" pot or larger to start your seed. Atlantic Giants can fill a 4" peat pot with roots in seven days.

There are several methods to start your seed. If you want to improve the speed and reliability of germination, especially if you are fortunate enough to have obtained a “hot” seed, there are a couple things you can do prior to placing the seed in the pot that will do much toward increasing your odds that it will germinate. 

First, very lightly file the edges of your seed with a nail file or fine sandpaper so that a very small amount of the seed coat edge is sanded away. Stay away from the pointed end. If done correctly, you should just start to see a color difference along the edge. This will aid moisture in penetrating the seed coat.

Next, soak your seed for up to eight hours in warm water before planting. This will give you a jump start in getting moisture into the seed. After soaking the seed, wet a paper towel and squeeze most but not all of the water out. Carefully wrap the seed in several folds of the paper towel and place it in a zip-lock bag, leaving just a bit of air inside. The seed then needs to be kept warm, optimally between 85 and 90 degrees. 

The warmer you keep your planted seed, the faster and healthier your seed will sprout. The easiest way is to simply place the zip-lock bag on a warm surface such as the top of a refrigerator or a computer monitor.

In three-to-five days, the seed should begin to sprout with a small taproot protruding from the pointed end. At this time you should have your pot and growing medium ready to receive the newly sprouted seed. Poke a hole in the growing medium and carefully place the seed in the hole, ensuring that the root is not pressed into the medium and that the top of the seed is slightly below the surface. Gently pack the medium around the seed with a fork until the hole is filled in to the surface of the medium. Now place the pot in either a warm sunny spot or back in your germination box until the seedling breaks ground. Try to maintain the 85 degree temperature day and night.

After your seedling breaks ground, if you’re using a germination box, remove the pot and place in a sunny window. A fluorescent light placed a few inches above the pot will help your seedling “green up” faster and prevent the stem from getting “leggy.” Short and stumpy is better than tall and lanky.

Continue to keep the soil moist, but not wet. Once your plant is about five days old, you should notice the first true leaf forming between the seed leaves. When this leaf grows to about 2 inches across it and the weather is cooperating, you’re ready to set your seedling in the ground inside the cold frame you erected earlier. Place the seedling in the ground up to the bottoms of the seed leaves, insuring that the first true leaf, the one in the middle, is facing opposite the way you want your main vine to run. 

Protect your plant

Once your seedling is in the ground, it is very vulnerable to the elements, even inside the frame. Pumpkin plants do not like extreme heat and will not tolerate the cold. At night in May, place a bucket or a box over your plant and cover with a blanket to retain as much of the day’s warmth as possible. Uncover in the morning when the temperature is above 40 degrees outside or 50 degrees inside the cold frame.

Water your seedling as needed to keep the soil moist but not wet. 

Your plant will be susceptible to disease through its lifespan. One of the most common is known as powdery mildew, identified by the presence of white powdery-looking spots on the top and bottom of leaves. Spraying your plant once a week with a fungicide such as Daconil will go far in keeping disease at bay.

Pests such as slugs, cucumber bugs and white flies are also a problem. A pesticide such as Liquid Sevin applied once a week opposite of the fungicide application should keep the bugs down. Begin pesticide and fungicide treatments after pollination, or earlier if a infestation occurs.

When vines start to grow

Your plant should start to vine in about two-to-three weeks, depending on the temperature and soil moisture. If your plant decides it wants to vine in the wrong direction, you can turn it in the right direction over the course of a couple weeks using a few stakes and moving the vine a little bit each day during the heat of the day, starting when the vine is about 12 to 18 inches long. At around five weeks old, your plant vine will grow up to one foot a day, so be prepared to stay on top of it from this point on.

As your vine grows, it will sprout what are known as secondary vines off of the main vine. These secondaries are where the plant gets much of its energy and should be nurtured as the main vine is. However, these secondaries will grow more vines known as tertiary vines or sucker vines. These vines rob the plant of valuable nutrients and should be pinched off when they appear.

Establishing a growing pattern for your plant is first. Growers use several patterns, but the most widely used pattern is the so-called “Christmas Tree.” Think of your plant as a Christmas tree, where the main vine is the trunk and the secondaries are branches. Train your vines so that the main vine runs generally straight out from the stump and the secondaries grow perpendicular to the main.

If you do not have enough room to grow your plant in that pattern, you can cut off all the secondaries from one side, allowing the main and remaining secondaries to be a bit longer. This is known as the flag pattern.

In either case, your main vine should be allowed to grow to a minimum length of 15 feet, although 20 feet or more is better. Your secondaries should be allowed to grow to a minimum length of 10 feet using the Christmas tree pattern and 14 feet using the flag pattern. Whatever pattern you decide on, your chances of growing a big pumpkin will be much better if you strive for a plant that covers 400 square feet or more.

Pruning is a vital part of the overall health of the plant. It not only keeps the vines contained within the space you have, but it improves air circulation for drying the plant surface to prevent conditions favorable to disease. When the vines reach the perimeter of the patch, simply pinch off the very end of new growth on the vine and bury the end, keeping in mind the optimum lengths listed above. 

Giant pumpkin plants have the ability to grow two taproots, where every leaf stock meets the vine. These tap roots can supply a larger volume of nutrients to your plant than just the main root system alone. Bury them just below the surface, trenching ahead of the plant as it grows. This provides the taproots an easier growing medium . Be very careful not to disturb the soil near the plant, you will destroy feeder roots.

Pumpkins require huge amounts of water, 500 gallons a week or more if your plant takes up 1,000 square feet. Remember to water at a constant rate and compensate for rain so the soil stays moist, but not wet.

Flowering vines

Around the last week of June, your plant’s main vine should be 8 feet to 10 feet long and growing fast. Pumpkins produce both male and female flowers, males having longer stems and females having a shorter stem with a bulb or baby pumpkin under the blossom.

The males will be the first to show and will be followed by the appearance of females a week or so after. Once the males start showing, they will come fast and furious for the next month or so. This is the signal that the time is near to pollinate. The ideal position to set a pumpkin is at least 10 feet from the stump along the main vine.

When each female first appears, try to make a small outward curve in your vine two feet on either side of the female so that the female or baby pumpkin is on the outside of this curve. This is to prevent stem stress later on. As your fruit grows to huge sizes, stems can actually press on the vine and pop your fruit off, ruining your season. Make the curve slowly and carefully over the course of a few days so as to not snap the vine. When the female is ready to open, the blossom will be about three inches long and will have an orange hue. The same goes for the male flowers. This means the flower will open the next morning.

The prime time to set your fruit is between July 1 and July 10. This provides the right amount of time for your fruit to grow and be ready for October, when most weigh-offs occur. If you only have one plant and are not concerned about preserving the lineage of your pumpkin’s genetic line for later seed distribution, you can let the bees do the work for you. However, if you’re after a big one and want to do all you can to insure a good fruit set, it’s imperative to properly pollinate by hand.

Observe the new pumpkins on the vine for 10 days after they have been pollinated. Note the shape, growth rate and skin texture as gauges for which one will be your main fruit. A good measure of growth rate is a 30 inch circumference at 10 days old. The skin of your fruit should be yellow, shiny and tender. Other aspects to take into account are stem length and position in relation to the vine. Your main candidate should be a fruit that has a long stem and is oriented as close to perpendicular to the vine as you can get. If all your fruit are at an angle of less than 90 degrees to the vine, choose the one that is closest to perpendicular to the main vine. You will be able to move the fruit very slowly toward 90 degrees. This will reduce stem stress when the fruit really starts packing on the pounds. Use extreme caution when moving your pumpkin, it doesn’t take a lot to crack or snap off the stem.

By Aug. 1, you should cull your fruit down to the one fruit on each plant that shows the most promise, taking into account the items listed above.

Drainage and pest control

You will need to place something under your pumpkin for it to grow on, something that allows water to drain as well as prevent pests from tunneling into your fruit from below. Many people use a three-to-four inch bed of play sand, while still others are now using belt material discarded by paper mills. As long as what you use allows drainage and prevents critters from destroying your fruit from below, you can use a number of different materials. The most important characteristic of the material you use for a bed is that it allows the fruit to grow and expand, unrestricted and with minimal resistance. If a material such as Styrofoam with holes in it is used, the chances of the friction between the fruit skin and the foam increases, causing the fruit to grow concave on the bottom and increasing the risk of a bottom split.

Beware Stem stress

Another form of stress, mentioned briefly above, is stem stress. Your pumpkin will grow at astonishing rates from mid-July to mid-August. In some cases gaining 20 to 40 pounds a day. This rapid growth can put tension on the pumpkin stem as the fruit grows in height and its shoulders grow toward the vine. Cutting the tap roots under the three leaves in either direction of the fruit will allow the vine to move upward as the pumpkin grows. Supporting the vine as it curves upward toward the stem is also a common practice. Ensure the vine does not rub against the fruit itself. You can train the vine by carefully pulling it away from the fruit shoulders with cushioned pieces of cloth. This method takes practice to learn and can run the risk of popping the fruit off the vine so use extreme caution when performing this method and only pull what the vine will allow every few days. Cut off any leaves that impede access to the fruit or may be rubbing against the skin of the pumpkin.

Your pumpkin can gain such large amounts daily because the skin is very pliable early on. However, cracks in both the skin and stem do occur. It’s natural for the stem to develop splits and heal over as it grows in size, however deep splits are an issue. If a split or crack in the skin of the pumpkin goes deep enough to enter the inner cavity of your fruit, your season is over, as the fruit will begin to rot very quickly. Many large pumpkins develop deep stem splits that do not go into the cavity, however if not cared for, they can continue to go deeper and ruin your season. 

The fruit of your labor

Hopefully you have grown an enormous pumpkin that will take all of your friends and neighbors to lift out of the garden! There are special lifting tarps made specifically for this, and are available at

The pumpkin can now be proudly displayed as the neighborhoods largest jack-o-lantern, or entered into a weigh-off, to show off your efforts. Hopefully, you can bring home a ribbon, or even prize money.


Special thanks to Thad Starr of Starr Farms in Pleasant Hill, Ore., for this detailed essay on growing giant pumpkins. Find out more about Starr Farms at

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