How to grow big pumpkins by Jim Eskew - 2008 season

April 24

seeds sprout up in my sunroom

The key to growing big pumpkins is in the seeds. If it's true that you reap what you sow, you might as well start out with seeds genetically predisposed to grow large, such as the Atlantic Giant variety. The seedlings have been planted and are just now beginning to germinate in my sunroom. Planting them about an inch deep in indoor pots, I used one half native Mecklenburg county clay and one half potting soil from Home Depot. Grow them inside until you are confident that the last frost has past.

May 2

vines are beginning to take root

The young pumpkin vines are now ready to be transplanted outside. I mixed about 20 pounds of chicken litter (broiler, not hen) into the soil three days beforehand and then relocated the plants from my sunroom to the yard. You want to shoot for a fertilizer with a high phosphorous content at this stage to stimulate root growth and since the chicken litter was free from my brother-in-law's farm it worked out well. I chose a place that was sure to get plenty of sunlight and dug a trench between the two rows for irrigation.

soil sample report, courtesy of the NC Dept. of Agriculture

Now if you are in Charlotte, we get a lot of acid rain thanks to weather patterns and the prosperity of Atlanta. So most of the time if you reside anywhere around the Piedmont, you'll have acidic soil and you'll need to raise its pH. Luckily, this is easy to do by applying lime. If you live somewhere else and your pH is too high, this is a more difficult problem to solve and you might end up needing to add sulfur instead. As you can see from this soil sample report, my pH level is around 6.9 which is in the ballpark for growing pumpkins (6.5 to 6.8 is ideal).

June 2

female pumpkin flower

After you start seeing Clemson Orange flowers budding, it is time for the males and females to "get to know each other" in the biblical sense. You can allow the bees to do this for you, but sometimes nature needs a little help. The best way to hand-pollinate is to yank a male flower off the vine and pull off the petals exposing the stamen. Now find a paint brush and a female flower and brush the pollen on the stamen into the stigma (internal parts) of the female flower. If you can't tell which flowers are male and which are female, the easiest way is just to look underneath the flower where you'll find a bulb (future pumpkin) if it is female.

June 15

pumpkin patch sprawl

By mid-June, my patch was getting out of control. I had no idea the six seedlings I started out with would overtake 400 sq ft of space so quickly. Had I known this, I would have started them out a little further apart. Since my research had indicated the prize-winners usually grow about 10 ft down the vine from the root, I decided to go out about 15 feet and hack away any extra vine and bury the ends. It was risky, but I couldn't afford to devote my entire back yard to the project.

June 29

peak growing time

In late June, I added a bit of fertilizer to the equation. You don't want to do this every week or your pumpkin will "tear off the vine and explode", or so I've been told. As much as I'd like to see that happen, I'd rather see it in someone else's garden, so I used a modest amount of fertilizer and it seemed to do the trick. I also used a lot of water over this period when the leaves looked droopy, but it's hard to tell you how much and how often because I just did it as needed between rainfalls.

If you haven't gotten a soil sample yet, I have no idea how you know how much fertilizer to put on your lawn. All you do is shovel some dirt into a box and send it to Raleigh where they analyze it and put up the results online. It's free in North Carolina, and if you tell them what you're growing (as long as it isn't cannabis sativa), they'll even send back how much lime, etc to put out.

How much fertilizer to apply is important, but can get complicated, so stay with me. Most people already know that fertilizer is ALWAYS sold by its N-P-K content. On my soil sample report (above), it says I need to use 20 lbs of nitrogen per 1,000 sq ft. So 20 pounds / 1,000 sq ft X the amount of coverage I need (20x20 plot = 400 sq ft) equals 8 pounds of nitrogen needed over the course of the year. Since the report recommended I needed fertilizer with 5% nitrogen content, this equates to 100 / 5 = 20 pounds of fertilizer to get one pound of nitrogen. So to find the pounds of fertilizer needed, multiply 8 pounds of nitrogen needed X 20 pounds of fertilizer to get one pound of nitrogen, which is 160 lbs of fertilizer needed. Since it comes in 40 pound bags, I need to buy 160/40 = four bags. Or, if I want to skip the workout in the parking lot, I could apply 2 bags of 10-20-10, as long as the ratio is the same. With this information (plug in your own numbers), you can now go into the store and know exactly what to get. For my purposes, I just used chicken litter instead since it was free, a renewable resource, and has a high phosphorus content (report indicated I needed about twice as much phosphorus as nitrogen).

July 14

an underperformer - had to be removed from the vine

In mid-July, it is time to weed out the lesser-performing pumpkins so more plant food can be funneled into the big ones. There might be 8 or 10 on one vine, so you have to pick the best. From what I hear, it is not so much important to keep the largest, so instead pick the one that is growing at the fastest rate. One way is to measure the birth of each pumpkin daily to determine which fruit to keep and which to abort. My fastest growing pumpkin at one point was gaining 5 pounds and about 6 inches in circumference in a 24 hr period.

Some people get overly scientific about this step by measuring the circumference of all their pumpkins daily, logging it into a spreadsheet, and then trending the data to look for the highest growth rate. Since I have to look at enough metrics at work, I just went out every few days and snapped off the ones I didn't like.

August 18

the monkey grass method (patent pending)

One of the problems with growing giant pumpkins is the tendency for the fruit to grow so quickly, it rips itself off the vine. The root cause of this is because the vine sits on the surface of the ground, while the pumpkin grows expanding in all directions. A well-known remedy is to dig a hole so the pumpkin can sit in the hole and continue to grow deeper while still perpendicular to the vine. I tried this, but I found that my hole was being filled up with rainwater after each storm, and I was concerned that my pumpkin would sit in the water for days and end up rotting or getting some kind of disease or fungus. So my solution was to route the vine into a patch of monkey grass (Liriope muscari) where the pumpkin in its early life would sit at the top of the monkey grass cushion and gradually compress downward as it increased in weight. This worked pretty well for me and kept the outside of the pumpkin dry since the water drained downward through the grass and away from the fruit.

September 1

fall harvest sitting in my utility shed

By early September the vines in my patch had started to deteriorate so I knew it was time to harvest. Obviously, without vines to deliver nutrients to the pumpkins, they were no longer getting any larger. This happened a bit sooner than I would have preferred, but I got a head start by beginning in late April, so I wasn't surprised or disappointed. In the first year growing, my largest weighed in at 58 lbs 6 oz. Not a blue-ribbon pumpkin, but heavy enough to make you strain lifting it over your head.

Next year's goal: a big enough pumpkin to fit a disco ball inside when carved out, which would make a really cool-looking jack-o-lantern...I will have to settle for lasers this year :)