03/26/2023
Dr. Christensen’s Pumpkin Growing Secrets
That’s right I am willing to divulge my secrets. Yes, all of them! Listed below, not necessarily in order of importance, are the secrets of growing a giant pumpkin.
1. There ain’t any secrets
2. Good seed
3. Good soil
4. Early season protection
5. Pruning techniques
6. Fertilizing
7. Watering
8. Fruit production
9. Late season protection
10. Good weather
11. Educate yourself
12. HARD WORK
#1. There ain’t any secrets. Sorry to disappoint everyone that figured there was a quick and simple way to do this. There isn’t. I’ve heard a lot of wives tales about injecting steroids, injecting sugar, feeding milk and planting on top of dead fish etc. etc. etc. They simply don’t work. Actually without #12 above 2-11 won’t matter because it doesn’t just happen by itself. You do not simply plant a seed in May and have a prize winning pumpkin in September.
#2. Good Seed. You will never grow a big one with a standard Jack-O-Lantern seed! All of the giants over 300 pounds are of the variety know as “Atlantic Giant”. This strain was developed by Howard Dill in Nova Scotia in the late 70’s. You can buy Atlantic Giant seeds in the supermarket but the quality is suspect. You don’t know where the seed came from, who grew it or what the genetics of it are. Most likely they will be from field grown pumpkins without any quality control. You are probably asking what are the genetics of pumpkin seeds. I can tell you the great, great, great grandparents of my 1003 pound pumpkin that I grew in 2008. By keeping track of the pumpkins genetics, good traits can be selected for and bad traits selected against. Keep track of the name and number of all seeds that you plant and the crosses that you make. Even if you don’t plan on growing your own seeds, by keeping track of what you planted it allows the person who gave the seed to you to get an idea of what kind of pumpkin that particular seed can grow.
First, a word on nomenclature. The seed package you received is probably labeled something like 857 Christensen 2006. This means that the seed is from a pumpkin that was grown by a grower whose last name is Christensen, it weighed 857 pounds, and was grown in 2006. Following that is (927 LaRue x 1016 Daletas). This is the cross of the pumpkin. By convention the female is listed first. My 857 was grown off of a seed from Bill Northrup’s 1101 pound pumpkin, it was pollinated with pollen from a plant grown from a seed from Dennis Daigle’s 670-pound pumpkin. The designation “DMG” stands for damaged, typically meaning the pumpkin had some sort of defect and was not considered a sound pumpkin. For example, my 717 had a blossom end split that went into the center of the pumpkin. The designation “UOW” means the pumpkin was weighed on something other then a certified scale.
#3. Good Soil. Now you can do as much or as little as you want in this category. If you really want a big one this is where the work begins. This is one of the variables that you do have some control over. The best place to start is with a soil test. This gives you some idea where you are at now and where you may want to be. The key to good soil is lots of organic matter. They say that the best patches have organic matter between 10-20%. I’ve spent six years raising my organic matter from 2 to 6%. It isn’t easy and it takes a lot of time. Part of the difficulty is that most of the organic matter decomposes (75% in the first year). This decomposition is what provides the building blocks required by the plant to grow a giant pumpkin. Manure is great but the fresh stuff can cause problems with too high of nitrogen. I typically put mine on in the fall and allow it to age over the winter. Compost is even better then manure but it is hard to produce in the quantity that is needed in a pumpkin patch. Leaves, straw, and hay are also a great source of organic matter but if put on in too large of quantities can tie up nitrogen and cause a nitrogen deficiency.
#4. Early Season Protection. Atlantic Giants take between 120 and 150 days to mature. If you look at the calendar we don’t have that many frost-free days in this part of Idaho. If you follow the old timers rule of not planting your garden until after the Memorial Day you won’t have a huge pumpkin. Most serious growers start their plants the last part of April. Typically I start mine on April 23rd. Within a week the plants are ready to go outside. In order to go out that early they need protection from the frost. I build temporary greenhouses out of PVC pipe and plastic, and even add supplemental heat on those colder nights. Don’t build too small of a cold frame as an Atlantic giant can easily outgrow a small cold frame in a matter of a couple of weeks. For first time growers, I would probably recommend starting your plants around the 7-10 of May. This is probably a good compromise between starting too early and having very large plants that are outgrowing a smaller cold frame and starting too late and missing a window for growing a giant.
A word about germination, Atlantic Giant seeds require warm temperatures (80-85 degrees). They will most likely rot if put out in the ground, or at best they will come up in mid June once the temperatures warm up. Soak them in warm water overnight and then put them in a 44oz Pepsi cup with the bottom cup out and the lid taped on. Fill this will a quality potting soil. The tapered sides let you lift off the cup without disturbing the roots once its time to transplant them outside. Put them someplace warm (a constant 85 degrees is the best) and within 4-7 days you will have pumpkin plants. Once you have plants they need to go outside in less the seven days. After that they start getting pot bound and pumpkins do not recover well from this. Typically my plants are set out within 2-3 days of breaking the surface.
#5. Pruning. In order to grow a big pumpkin you must be able to control growth of the vines and channel nutrients to the pumpkin. I typically grow in what is called a “Christmas Tree” style growing only one pumpkin per plant (see diagram below). If you use your imagination and imagine the plant from above the plant will look like a Christmas tree in mid July. I let the main vine grow in a straight line, secondary vines are allowed to grow to the edge of the patch (about 15’) and then they are terminated. All tertiary vines are aggressively destroyed. Pruning is something that needs to be done on a daily basis from the first of the season. As the vine grows dig a 4-6” trench in front of the growing tip and put the dirt on top of the vine that is already developed. This buries the vine several inches below the surface of the soil. Burying the vines is one of the most important parts of pruning. Roots will form at each node (that’s where the leaves come off the vine at) this will increase the ability of the plant to take up water and nutrients, and has a side effect of stabilizing the vines and leaves in the wind.
Seems like a good place to mention weeding. The best thing to use is a good old-fashioned hoe or my favorite is one of newer styles of “stirrup hoes”, but use whatever device you like. You don’t want to be digging too deep close the plant. The root system of an Atlantic Giant is quite extensive and you will find roots 6-8 feet beyond the end of the vines. Use the roto-tiller with extreme caution. This is another job that is much easier if done a little every day rather then trying to start in July
#6. Fertilizing. Yes, I do use Miracle Grow! I don’t use it all season long but at the start of the season I use it, in mid season I use a balanced foliar fertilizer (Fertilome 20-20-20 available from Town and Country Gardens or Peters 20-20-20 available from Fred Myers are two examples) and then late season I use a high potassium fertilizer. Typically I will use a foliar fertilizer on a weekly basis. I essentially follow the fertilizing plan outlined in How to Grow World Class Giant Pumpkins. I also use fish/seaweed emulsion on a weekly basis, Alaska Fish Emulsion is the most commonly available. Pre-planting fertilizing is done based on soil test results. Sorry no real secrets here. If a little is good a lot is not necessarily better. If you’ve done step three adequately you will not need to do much here. There is growing evidence that in the long run chemical fertilizers may actually do more harm to the soil, and soil life then they do good.
#7. Watering. Actually not much here either, if it is dry then turn on the sprinklers. I have mine set up on an automatic timer so that it will water every third day. As a rule of thumb they say that pumpkins will need 1 inch of water every week. In our dry, arid climate I think this is probably too little water. I probably give about an inch every time I water. Use some common sense here. Again if a little is good a lot is not necessarily better. Too much water leads to problems with diseases and poor plant growth.
#8. Fruit Production. This is actually a fairly detailed step with a bunch of factors that I’ve lumped in together. Any one of these alone will not make a great pumpkin. However, don’t pay attention to just one of these steps and your season my come to an early end.
. Pollination. A little lesson on the birds and the bees of growing pumpkins is in order here. There are two different types of pumpkin flowers on the same plant. Male flowers produce the pollen and female flowers produce the pumpkin. They are quite easy to tell apart as the female flower has a small pumpkin underneath it. The flower typically will open first thing in the morning. Once it opens you have a 4-6 hour window to pollinate it, after that it is too late. The bees might take care of it but do you really want to leave it to chance. If the bees do it for you, they are just as likely to pollinate it with the pollen from your banana squash or your neighbors (that lives ½ mile away) Hubbard squash.
Pick 2-4 male flowers that opened that morning. Rip off the petals of the male flower thus exposing the stamen and gently rub the middle part of the female flower (stigma) with the stamen. If you really want a guaranteed cross that you would be willing to grow the seeds from next year, then you must cover the flower before and after it has been pollinated. Otherwise, there is nothing to keep that bee covered with the Hubbard squash pollen out of the flower and having a mixed pollination. Some seeds may pollinated with pumpkin pollen and others with Hubbard squash pollen, and still others with Banana squash pollen. I typically take a piece of twine and tie it loosely around the petal of the female flower, thus keeping unwanted visitors out of the flower.
. Cull to one pumpkin. This can be an emotional challenge. Several growers have shown up to the weighoff with 15 pumpkins from one plant. Unfortunately none of those pumpkins are really big. There has been too much competition for nutrients and you end up with a bunch of mediocre pumpkins. If you want to grow one bigger then mine you will have to do this. Typically I set several fruit and then measure them on a regular basis for about 10-20 days and see which one is growing the best. All fruit do not grow equally. Other things to consider besides the rate of growth are the shape of the fruit, the length of the stem and whether it is on a main vine. Main vine fruits do better then fruit on secondary vines. I did grow a 709 on a secondary vine in 2004 simply because my main vine fruit was much slower growing so I culled it. I have grown two per plant before but this is on a plant that is pruned with in double Christmas tree and the plant takes nearly 1300 square feet.
. Eliminate stem stress. What the heck is stem stress? As a pumpkin approaches 3-400 pounds it begins to get large enough that the shoulders on the pumpkin put pressure on the vine. This pressure can literally rip the fruit from the vine. It can cause the pumpkin to have a weird shape. About the time you pollinate the blossom that might become “the one”, begin training a 90 degree bend in the vine with the blossom positioned at the outside curve (see diagram below). Then about 3 feet beyond the blossom straighten the vine out so that it is headed in its original direction. This positions the vine away from the shoulders of the fruit and will help save the day in the end.
As the pumpkin begins to grow, it will lift the vine up. At this point, it becomes necessary to cut the tap roots 2-3 nodes in either direction thus decreasing the downward pressure that the vine produces on the stem.
. Fruit shading. The fruit can and will get sunburned. This can cause hardening of the skin and limits expansion and growth of the pumpkin. It can also lead to significant cracking and scarring of the pumpkin as well. Typically growing giant pumpkins is not a beauty contest but there is no reason to intentionally challenge them. I cover the pumpkin with a tarp supported on a frame of PVC pipe. This keeps the sun off the fruit and keeps the soil under the pumpkin dry
. Protecting the bottom of the fruit. Huh! Bet you never thought of this. There are actually two reasons to do this. It helps keep the bottom of the fruit dry and decreases the likelihood of having your fruit rot from the bottom. It is the pits to have a 700 pumpkin rot because it was not kept dry.
The second reason to do this is that the bottom of fruit pushes along the ground as it grows. If it drags on the dirt or uneven soil then it forces the blossom end into the ground resulting in an ugly shaped pumpkin that is more likely to split.
This is done by putting something under the pumpkin. I have used 1” Styrofoam sheeting under the pumpkin, but I think sand works better and is easier to lay down. When the pumpkin gets about the size of a basketball gently lift it up and place about 2” of sand under and around the pumpkin. This is a two person job. The sand moves around easier as the pumpkin grows. It also drains and dries faster the soil and keeps the fruit drier.
#9. Late Season Protection. This is one of the most difficult tasks. No it is not necessary, but if you really want a giant it is a must. I can get 200 pounds of growth in September but not if it freezes on September 1st (typical for Idaho). I don’t cover each plant, just that of my biggest pumpkin. By covering the entire plant and adding supplemental heat you can keep the plant alive and thus the pumpkin growing until it is time to be picked for the weigh-off. I have constructed a frame and draped it plastic to cover the plant. If you really want some information give me a call. It will most likely require so ingenuity to get this job done.
#10. Education. This is a nice little primer on growing pumpkins but it is not meant to be all-inclusive. Read as much as you can, ask questions, and visit other growers. Some suggestions on where to turn. How to Grow World Class Giant Pumpkins Volumes 1, 2 and 3, are invaluable resources with a wealth of information. They are the best-written resources out there. They can be ordered through Amazon.com. Numerous online resources exist the best is www.Bigpumpkins.com; it has lots of advice for beginners and long time growers alike. If you have questions feel free to call me or to drop me an email. I love to talk pumpkins.
#11. Good weather. Sorry, I do not have a weather control station…..yet? If you really want to have better pumpkin weather, move someplace with more mild temperatures. I would suggest Washington, Oregon, or New Hampshire (this is where all the big pumpkins come from). Short of that you are on your own.
#12. Hard Work. I really don’t know how much time it takes, but it is a lot. Ten hours a week is probably a safe estimate. The busiest seasons are early spring, getting the patch ready. Late June and early July is pollination time as I’m getting up at 5:30 to pollinate the pumpkins and then burying the vines in the heat of the day when the vines are more pliable, and less likely to break. This is also when the weeds seem to be flourishing. Believe it or not October is also a very busy season getting the patch ready for winter, hauling manure, getting soil samples, collecting leaves and chopping hay. If you’re afraid of some nice physical labor growing pumpkins is probably not for you.
Brian W. Christensen MD, FACS
20 Madison Professional Park
Rexburg, Idaho 83440
www.brianchristensenmd.com
Email Bchris1335@aol.com
Call Brian Christensen MD at 208-656-9008. Short wait times. Board certified surgeon. Practicing since 1998. Surgery, general surgeries, surgery services.
