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Picture of Giant Pumpkins make Giant Jack o Lanterns
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     I have been growing giant pumpkins for awhile now and after my first year I was hooked I had an amazing time growing them and they made an awesome addition to my Halloween décor for many reasons.  First of all it’s just incredible that something can get that big. I am just amazed you can grow a 500 pound pumpkin from a relatively small seed.  Secondly I can pretty much guarantee that no one else in your neighborhood will have anything close. I don’t think we had one trick or treater not make a comment or take a picture.  Also it gives you some insurance against would be pumpkin smashers cause they are impossible to lift on your own.  Lastly the sheer size of the Jack o Lantern when you carve it allows you to do some cool things, more on that later.  So put in a little work this summer and you will have the biggest jack-o-lantern on the block.
       Now you can get really crazy with this or keep it very simple.  My first year I did not use all the different fertilizers i will talk about here and I grew a nice 275 pound pumpkin. After that I started doing more research found a fertilizer program i liked and the following year I grew a 520 pounder and I am no where near as involved as some people.  So it’s up to you but in this instructable I will show you what I have done to consistently grow 400-600 pound pumpkins.
     There are a lot of places online to get supplies, I have been using www.hollandsgiants.com and they have been great.  You can get everything you need there and much of the fertilizer program that I use is taken from the one that they have designed and have available on their site.
 
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Step 1: Early Spring: Prepare the patch

Picture of Early Spring: Prepare the patch
Early Spring - Prepare the patch
What you will need:
* Garden plot
* A good digging shovel
* Composted Manure
* Fertilizer (see below)


 Pick a spot for your pumpkin patch that gets as much sun as possible pumpkins love full sun.  As soon as the weather permits (ground thaws) you want to till the pumpkin patch. Ideally you want a space about 20 x 20 per plant but if you don’t have it you can just let the vines grow out of the patch. Mine is 20 x 40 and allows me to grow two plants.
   
After you till the patch grab a soil test kit from the garden center and see what you soil levels are, you are looking for a PH of 6-7.  If you are outside the range the kit should also provide info on how to amend your soil accordingly.

     Next, at the end of the patch, where the seedling will be planted dig a hole about 4 feet wide and 3 feet deep.  We are going to pack this hole full of nutrients for your pumpkin.  I add composted manure, and a Mycorrhizal Fungi (*see below) to the soil I dug from the hole,  I mix it up and then fill the hole back in. Make sure to mark the center of the hole after you fill it back in so you know where to plant your seedlings when the time comes.

*Mycorrhizal Fungi is a fungi that bonds to the roots of the pumpkin plant and in exchange for sugars from the plant sends out tiny hair like roots of its own much smaller than any roots on the pumpkin plant alone.  The hair like roots make the plant way more efficient at pulling nutrients from the soil. 

      The last step in preparing the patch is to work some fertilizer in a 8-10 foot circle around the planting site.  You can use a basic 10-10-10 fertilizer from the local store and still grow really big pumpkins but to really maximize growth you want to change the fertilizer as the plants hit different stages.  In the plant growth stage, they like a lot of nitrogen so you want to look for a fertilizer that focuses on the first number in that sequence.  As I said I get my supplies from www.hollandsgiants.com because they specialize in giant pumpkin growing.   I use Pumpkin Power 9-3-4 and Spring wake up to prepare my patch.

Step 2: Mid April: Plant the seeds

Mid April - Plant the seeds:
What you will need:
* Dill’s Atlantic Giant Seeds
* 5 inch Peat Pots
* Seed Starting soil
* Seaweed Fertilizer
* Nail File

You want to start the seeds about two or three weeks before the last frost. I live in Massachusetts so I start mine in mid April.

First the seeds, there is only one kind to use Dill’s Atlantic Giants. No other variety has produced a bigger pumpkin; this should be your only choice if you want size.
Lots of online sites have them including holland’s giants and depending on the pedigree of the seeds they can get pretty expensive.  Another route is to find a grower and ask them. Sites like www.bigpumpkins.com are a great resource. They have tons of members that will help answer question and will often share seeds.  I have a ton of seeds from my pumpkin so shoot me a message and I would be happy to send you some.

Now we are going to need to prep the seeds. The shell of the Atlantic Giant seed is real thick and in some cases can prevent the seedling from breaking out, so it is best to file down the edge of the seed (check out the picture for a reference) I just used a nail file.

Next you want to soak the seeds in warm water.  I also like to add a little seaweed powder to the water.  Let them soak for an hour or so. While the seed are soaking grab some 5 inch peat pots and fill with a seed starting mix.  It is helpfull to mix in some Mycorrhiza soil innoculant (discussed in patch prep) as well.  After the seeds are done soaking bury them pointed end down only about ½ inch below the surface, then water the pots well.

I keep my pots under a fluorescent shop light that I leave on 24/7 while I am growing them indoors.  I have mine hanging on a chain so I can raise it as the plants grow. You also want to keep the pots warm 80-90 degrees, since mine are in the basement I bought a heating pad that I keep the pots on top of.   I also keep the pots covered either with a clear plastic cover or saran wrap works fine as well.

Now we wait…water the soil when it starts to dry out and you should see the seedlings start to emerge in 5-7 days.  Keep them growing inside till at least the third leaf is on the plant.  You should also mark the direction of the third leaf as this is the direction the vine grows in.

Once the plant has developed the third leaf it can be planted in the patch, just make sure the weather is clear of any frosts. A few days before you are going to plant the seedling in the garden start bringing them outside during the day so they get used to being outside. This will minimize any shock to the plant.

Step 3: May: Planting

Picture of May: Planting
When you are ready to put the plants in the patch find the marker you left in the hole that was dug out. You want the plant to be raised slightly above the patch so mound the dirt some at the site maybe 4-5 inches high. Once you have created a small mound dig a hole big enough for the peat pot, plant the whole thing together.  When the plants were growing inside you should have marked off the direction of the third leaf, point this in the direction you want the vine to grow. There is no need to remove from the pot as this will decompose in the soil.  After you have the plant in the ground water the area thoroughly.

At this point the plant is still very vulnerable so depending on the weather you may need to take some extra precautions. When I plant mine it is still pretty cold out so I built a little hoop house over it.  Basically it’s a small wood frame with some clear plastic sheeting covering it, you can find lots of designs online but they are very easy to build.  The hoop house will help keep the plant warm at night if the temperature drops and protect it from wind while the plant develops its root system. Just make sure you provide ventilation in the hoop house if the temp gets high during the day, you don’t want to cook the plant.

Step 4: May - Early June: Initial Growth

Picture of May - Early June: Initial Growth
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At this point its mostly maintenance work until we start to get some flowers on the plant which will be several weeks.

Watering the plant should be done once the soil starts to dry out.  The way I tell if the patch needs watering is: I grab a handful of soil an inch or two down and squeeze it into a ball, when you release if the soil stays caked up you are fine if the soil crumbles its time to water.

Fertilizer: You will end up watering the patch around 3 times a week.  If you are using a basic fertilizer I would do this once a week when I water.  If you are going to go the more advanced route alternate at each watering a soluble seaweed fertilizer and a soluble calcium powder.  Once you get to mid June we want to change our fertilizer to focus more on Phosphorus and Potassium the second and third numbers in the fertilizer sequence.  These nutrients help with blossoming and pumpkin growth.  I used Nutri-Aid Blossom Booster and Fruit Finisher 0-52-34.  So around June 10th work this into the rotation as you water.

Pests:  There are two big one that can seriously ruin your pumpkin plant. The first one is the Cucumber beetle; I have a lot of experience with these. This year they were out early and I was on vacation. When I came back they had already eaten a lot of my plant, fortunately they are easy to deal with. As you are in your pumpkin patch keep an eye out for these bugs and at the fist sign of them start using Sevin pesticide on your plant.  I used the concentrate that I mixed and applied with a sprayer. With regular application I had no further issues.
The second major pest is the Squash Vine Borer; luckily I have not had any issues with these yet.  They bore into the vines of the plant and seriously damage them.  They are hard to detect before they have already wreaked havoc so the best way to prevent them is to spray Diaznion on the vines before hand.

Pruning and Training: The plant is going to send of a main vine and off of the mine vine secondary vines will grow. As the plant grows in this fashion you want to train the vines to grow in the shape of a Christmas tree.  So you want the main vine to grow straight and the secondary vine to grow off of the main straight and perpendicular.  This will allow you to maintain the plant as well as position the pumpkin correctly as it develops but we will get to that later.  The secondary vines will throw off tertiary vine and these should be pruned off.   The reason for this is that you want the plant to be large enough to support a giant pumpkin but not use important nutrients to grow the vines.
Another important step here is to bury the vines as you will see referenced in the fertilizer program.  When the vines start to get long 7 or so feet you want to bury them as  they grow but allow 1 ½ feet of open vine at the growing end.  We do this for two reasons, it protects the vines from pests as well as promotes a secondary root system to really fuel the pumpkins growth.  This is time consuming and never ending as these plants will grow like crazy but trust me, its worth it.

Step 5: Mid June - Early July

Picture of Mid June - Early July
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Polination: Around mid June when the plant is several weeks old and several feet long you will start to get flowers on your pumpkin.  There are two types of flowers, male and female.  They are easy to tell apart as the female flower will have a small bulb at the base (this is the baby pumpkin), the males will not.  You can leave the pollination to the bees if you want. I have had success leaving nature to take its course but if you really want to be sure you can take matters into you own hands.  Check the plant in the morning to see what new flowers have opened.  When you have a female flower open you want to find a few males, peel the petals off so only the middle part is left, then rub that inside the female flower.  Some serious growers get very heavy into genetics and like to use male flowers from other plants to try and create the ultimate cross but you can use the ones from the same plant just as well.

Step 6: July: Pumpkin Growth

Picture of July: Pumpkin Growth
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If the pumpkin was pollinated then the small bulb at the base of the flower will begin to turn yellow and grow.  Don’t worry if it doesn’t happen to the first few, as I have found the plant knows when its able to start supporting a pumpkin.
By late June you should have several small pumpkins growing on the vines.  The big decision now is, which one you will let grow.  In order to achieve the biggest pumpkin you ideally want to have eventually only one on the plant.  However if you do want multiple pumpkins you cant still get a couple really big ones on the same plant. I let two grow on the same plant one year and got a 175 pounder and a 420 pounder. 
You want to keep an eye on the ones you have growing, you can even measure to see which ones seem to be growing the fastest.  You will use this along with their placement on the vine to make your decision.  Pumpkins on the main vine grow the best and you want one around 12 feet out or so from the stump.  When you have some well positioned pumpkins that are growing start to cull the others off of the vine until you are down to your two best, I leave one on a little longer for insurance.  Finally when I feel good about my choice I remove the last one so the plant can focus on a single pumpkin.
Another thing to consider is how the pumpkin is positioned in relation to the vine.  You want the stem of the pumpkin to grow perpendicular to the vine, if  not as the shoulders of the pumpkin grow it can snap itself off the vine.  When the pumpkin is young SLOWLY!!! over the course of a couple days reposition the pumpkin so the stem is in the right position. Also make sure that the vine three feet on each side of the stem is uncovered and free of any roots connecting it to the ground so that the vine can rise up as the pumpkin grows.
You also might want to consider building some type of shade for the pumpkin itself.  This is not absolutely crucial but the sun can dry out the skin of the pumpkin making it susceptible to cracking.  Yes… they can grow so fast that they actually split their skin. I have see people build little tent and other just use an umbrella stuck in the soil.
Lastly you want to put something under the pumpkin to prevent rot from sitting in wet soil and also to deter any would be burrowing animals.  What I have found works best is a square of landscape fabric with a pile of sand on top.  Make sure you do this early enough before your pumpkin is too heavy to lift

Step 7: July - October: Packing on the pounds

Picture of July - October: Packing on the pounds
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From here on out it’s really just maintenance.  Follow the same fertilizer schedule, water as needed, keep burying the main and secondary vines and pruning off the tertiary vines. As the plant begins to get huge, and it will, you can start to cut it back some.  Once the main vine gets ten to twelve feet past the pumpkin you can cut it off and bury the end and do the same for the secondaries once they reach 13 or so feet.  Again doing this allows enough plant to grow a huge pumpkin but not so much that the plant is pulling resources away from pumpkin growth.  You will be amazed at how fast these pumpkins grow they can put on 20 – 30 pounds a day and will continue to grow till the end of September.  As the weather starts to cool down it’s a good idea to cover the pumpkin at night with an old blanket to keep it warm (no joke).  You want to try and keep the pumpkin from hardening off for as long as possible so it will continue to grow.

Step 8: Its Ocotober!!!

Picture of Its Ocotober!!!
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So you have made it to october, the vines have all died off, and you are left with your massive pumpkin.  What to do now??? CARVE IT!!!.  First of all moving the pumpkin is tricky but I have had sucess rolling the pumpkin onto a tarp with the help of some friends and draging it by hand and with my riding lawn mower.  Make sure you move it into position before you carve it.

Step 9: Halloween: Carving

Suprisingly these pumpkins are pretty easy to carve.  Carve them just like you would a normal pumpkin but you have to step up your tools.  I used a sawsall and a dry wall saw to carve mine and it worked well.  I also used a garden trowel to scoop and scrape the insides.

Lighting was the tricky part for me it took me awhile to figure out how to get enough light while still keeping that great glow you can only get from a flame. So for the big pumpkin I used a small propane lantern and the smaller on I used the inside part of my TIKI torches.   Both worked really well.

The best part about having a giant jack o lantern is you can get creative with it.  I wanted to kick it up a notch and since I had so much room in the pumpkin I added a fog machine.  I ran the remote for the fog machine into the house and as trick or treater walked by the pumpkin would shoot smoke out of its mouth.  This was a huge hit this year and got more than a few scares.

So there you go...I hope you enjoyed it.  Once you start growing these bad boys is addicting so good luck and get creative. 

mmays14 months ago
How can I get some seeds?
Reiff1 year ago

Well I tried a giant pumpkin this year, unfortunately I wasn't ready for vine borer bug, I pulled out a bunch larva, got rid of a clump of eggs, and removed two vines. I did the best I could and patched the holes up with mud, but I just don't know what to think yet, I guess I will have to try again next year. Beware pumpkin growers! the vine boarer bug will really ruin a couple months of work.

Super... Will try next Year here in Germany in my compost....200 pound would be Good , so You Feed the plant with milk?I heared about that... Great Job
Reiff1 year ago
You have very nice soil there. like I said I live in Lancaster Pa, and we have rocky soil. Although, you seem to be much more of a gardner than we are.
Reiff1 year ago
Boy, I would love to harvest a pumpkin like that. As we all know what happens when you stick a pumpkin in a compost pile. My last years pumpkin made some really good pumpkins this fall, as they were planted (by accident) in the compost/brush pile. The biggest I ever had, but really there kind of "average, big". If I can get this parental approved, I would collect horse dung everywhere (good thing I live in Lancaster Amish county).
I have seen such a big for the first time......
rocklocker2 years ago
This is about the most detailed account of how to grow a giant pumpkin. Now I need to find a spot in the yard to do this. Great job.
Thanks for the knowhow to grow these giants ourselves! Great Instructable!
mikeasaurus2 years ago
That's a mighty big pumpkin! I always wondered how this was done.
That is amazing! You really went all out. :D
poofrabbit2 years ago
WOW that is one BIG Jack-O-Lantern! Very nice job!