Starter guide
Turn one seed into a pumpkin you need four friends to lift.
Giant pumpkin growing is raising a single plant of a variety bred for size, pruning it to one fruit, and seeing what that fruit weighs in the fall. Growers start a seed indoors in late April, plant it in a big patch of rich soil, hand-pollinate a flower around the start of July, then spend the summer watering, feeding and burying vines while the pumpkin gains several pounds a day. A first-year grower with decent seed and soil often ends up with 200 to 400 pounds; the world record is over 2,700. The draw is the weekly tape measurement and a weigh-off at the end where everyone's season goes on the same scale.
The season runs about five months and each stage has one job. Late April to mid-May is indoors: one seed, one large pot, a warm spot. From transplant to the end of June the plant builds vines, and you spend an hour or two a week steering and burying them. Early July is pollination, the week the season turns on. After that the pumpkin does the growing and you keep it supplied: water most days in dry weather, feed weekly, measure once a week. Peak growth in August can add 10 to 30 pounds a day on a good plant, so a missed week of watering shows up on the scale. Late September or early October is harvest and the weigh-off.
Variety
Only the Atlantic Giant type reaches these sizes. A field pumpkin or a jack-o'-lantern variety tops out around 20 to 50 pounds however well you feed it.
Seed source
Packet seed from a garden supplier is fine for a first year and can pass 400 pounds. Seed from a named heavy pumpkin, sold or given away by growers' clubs over the winter, is the upgrade for year two.
Space
Plan on at least 400 square feet for one plant, about 20 by 20 feet. Extension guides recommend 1,000 square feet if you have it, and more leaf area means more pumpkin.
Sun and water
Pick the spot with the most direct sun and a hose bib within reach. You will be watering there most days from July on.
Soil
Giant pumpkins want deep, loose soil that drains, with a pH of about 6.5 to 6.8. Test before planting, while there is still time to correct it.
Fresh ground
Soil that has not grown squash, melons or cucumbers for three years carries fewer of the diseases that kill vines in August.
Late April to the first frost
Find your last frost date first, free
What you can get done in your first month
A sprouted seed
Filed, soaked and kept warm, a giant pumpkin seed is usually up within a week.
A prepared planting spot
A 10-foot circle with compost dug in, ready before the seedling is.
A soil test result
The pH number tells you whether the soil needs correcting before the vines cover the ground.
A plant in the ground under cover
Transplanted at the first true leaf and growing its main vine inside a tunnel.
Telling the flowers apart
A female flower has a small round pumpkin under the petals. A male flower sits on a thin plain stalk. Males appear a week or two before the first female.
Vine pattern
Most growers use a Christmas-tree layout: one main vine down the middle, side vines straight out both sides, and every third-level shoot pinched off. It keeps the plant inside the patch and easy to walk.
Reading the leaves
Leaves that wilt at midday and recover by evening are normal in heat. Leaves still limp at dusk mean the roots are short of water or the vine is diseased.
Estimating weight
Take three measurements in inches: around the pumpkin at its widest, over the top from ground to ground side to side, and over the top from ground to ground stem end to blossom end. Add them up and look up the total in a free over-the-top weight chart.
Feeding by stage
Go easy on nitrogen before fruit set, or the plant makes vines and drops its flowers. After the pumpkin sets, potassium matters more.
Three places a first pumpkin can go
Start here
Find the sanctioned weigh-off nearest you and put its date on the calendar before you sow. Read its entry rules now, because a pumpkin with a hole or soft rot gets disqualified.
Start here
Call your county or state fair office this spring and ask for the exhibitor handbook. It lists the largest-pumpkin class, the entry deadline and whether you need to pre-register.
Start here
Sow a giant tomato or long gourd variety alongside the pumpkin this spring, and ask your nearest weigh-off which classes it runs besides pumpkins.
Open a card for the first thing to do. The vegetable showing card has a button that adds its two lines to the patch list.
Planting out too early
One frost or a week of cold soil sets the plant back further than sowing two weeks late would have.
Keeping too many pumpkins
Two fruits on one plant weigh less together than one would alone. Thinning down to one is the hardest cut of the year.
Too much nitrogen
Dark, huge leaves and no fruit set in July usually means the plant was overfed in June.
Splits
A dry spell followed by a heavy soaking makes the pumpkin grow faster than its skin can stretch. Even watering matters more than a lot of water.
Stem stress
As the pumpkin gets taller it lifts the vine with it. If you do not loosen the vine's buried roots for 3 feet either side of the fruit, the stem tears.
Pests and mildew
Squash vine borers, cucumber beetles and powdery mildew all arrive in midsummer. Check under leaves and at the base of the plant twice a week and ask your county extension office what is allowed for squash in your state.
Expecting a record
Half-ton pumpkins come from years of soil building and proven seed. A first pumpkin over 200 pounds is a good season.
Start with a university extension fact sheet, which covers the full season in a few pages. Then read grower diaries: experienced growers post what they did week by week, with photos, so you can compare your plant against one in a similar climate on the same date. State and regional growers' clubs run winter seed sales, spring seminars and patch tours, and most members will hand a newcomer a few seeds. The body that sanctions weigh-offs publishes the rules your pumpkin has to meet and every site's results.
Free guides, diaries and weigh-off rules
Four lines to plant, six to add pounds
The four essentials get a plant into the ground: seed, a pot big enough for a root system that outgrows small cells in days, sterile starting mix, and compost for the planting spot. Everything in the recommended tier pays for itself in pounds. The heat mat gets the seed up fast, the soil test tells you what to add, the tunnel protects a frost-tender transplant, and the soaker hose, fertilizer and tape measure are what you use every week from July to harvest. Shade and padding for the fruit can come from an old bedsheet and a scrap board. The showing add-on is only for entering other vegetables, and the lifting tarp can wait until you know how heavy your pumpkin is going to be.
Compare the options on each line, then set your tiers and check out from the patch list. Clicking a card selects it there, and clicking the selected card again takes that line out. The seed, pots, mix, compost and the six recommended lines start in the kit. The two vegetable showing lines and the lifting tarp start out.
Size is in the genetics, and no other variety gets into the hundreds of pounds. One packet gives spares in case a seed fails.
Sow Right Seeds - Atlantic Giant Pumpkin Seed for Planting Large Pumpkins
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Seed Needs Atlantic Giant Pumpkin Seeds to Plant Vegetables - 2 Packs
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Sow two and keep the stronger seedling. Leftover seed keeps for several years in a cool, dry place.
A giant pumpkin seedling fills a small cell with roots in days and sulks if they are disturbed. A large pot that goes into the ground with the plant avoids both problems.
Back to the Roots Organic & PLANTABLE 4.25" Wide Seed Starting POTS (8 CT)
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Daniel's Plants 4" Naked Pots | Large Natural Plantable Seed Starter Pots | OMRI-Listed Biodegradable for Seedlings | Enhanced Aeration | Earth Friendly - Peat Free | 30 Pack 4 Inch Round
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Pick pots 4 inches across or larger. Tear off the rim above soil level at planting so it does not wick water away from the roots.
Garden soil in a pot stays wet and rots a pumpkin seed before it sprouts. A light, sterile mix drains and warms quickly.
Seed Starter Soil Mix for Germination and Growth, Made in USA, 4 Dry Quarts
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Espoma Organic Seed Starter Premium Potting Soil Mix - All Natural & Organic Seed Starting Mix with Mycorrhizae. for Organic Gardening, 8 qt, Pack of 2
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FoxFarm Light Warrior Seed Starter Growing Medium, 1cu ft - Beneficial for Seed Germination and Root Development, Indoor/Outdoor Cultivation - Ideal Nutrition for Plant Seedlings
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One 8-quart bag fills several large pots.
The plant feeds from the top foot of soil, and organic matter is what holds water and nutrients there. Compost dug into the planting spot is the cheapest weight you will add all year.
Michigan Peat Garden Magic Odor-Free Compost & Manure Blend, 40 lb
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Black Kow Composted Cow Manure 20 lbs
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Michigan Peat Baccto 1640 Wholly Cow Horticultural Compost and Manure for Soil Amendment, Lawn Care, & Garden Beds, 40 Quart Bag (2 Pack)
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Bagged compost is fine for the planting circle. For the whole patch, a bulk delivery from a landscape yard or a neighbor's aged manure costs far less per cubic foot.
Pumpkin seed wants 80 to 85 degrees F to sprout, far warmer than a spring windowsill. At room temperature it can sit for two weeks and rot.
MET Certified 2 Pack Seedling Heat Mat, Seedfactor Waterproof Durable Germination Station Heat Mat, Warm Hydroponic Heating Pad for Indoor Home Gardening Seed Starter(10" X 20")
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iPower Seedling Heat Mat for Plants with Dual Digital Temperature Controller, 10" x 20.75", Black
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A mat with a thermostat holds the temperature for you. Without one, check the mix with a kitchen thermometer.
Outside a pH of about 6.5 to 6.8 the plant cannot take up what you feed it. A test before planting tells you whether the soil needs correcting and by how much.
Rapitest Soil Test Kit for Gardens, Vegetables, Flowers and Lawns. USA designed and assembled soil tester completely, quickly and accurately measures/analyzes soil pH acidity and garden nutrients
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Your state extension lab runs a fuller test for a small fee and is worth doing once the hobby sticks.
The plant goes out weeks before the weather is reliably warm, and one frost kills it. A small tunnel holds heat and blocks wind for the first month.
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Outsunny 7' x 3' x 2.5' Mini Greenhouse Portable Tunnel Green House Clear
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Tierra Garden 50-5010 Haxnicks Easy Fleece Tunnel Garden Cloche, Giant
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Open the ends on sunny days so it does not cook. Take it off once the vine reaches the end.
Water at soil level reaches the roots along every buried vine and keeps the leaves dry, which slows mildew. It also frees you from an hour a day on the end of a hose.
Gilmour 50' Black Flat Weeper Soaker Hose for Garden Beds, Drip Irrigation Outdoor Hose, Flexible Garden Hose for Vegetable Gardens, Flower Beds, Lawns, and Orchards
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Rocky Mountain Goods Soaker Hose - Heavy duty rubber - Saves 70% water - End cap included for additional hose connect - Great for gardens/flower beds - Reinforced fittings (50-Feet by 5/8-Inch)
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Water Right Polyurethane Soaker Hose, 50 Ft, Non-toxic, 1/2” ID, Pine Straw
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50 feet covers the main vine and a few side vines of a first-year plant. It connects to an ordinary garden hose.
A plant adding pounds a day uses nutrients faster than compost releases them. A dilute weekly feed keeps growth steady through August.
Southern Ag PowerPak 20-20-20 Water Soluble Fertilizer with micronutrients (5 LB)
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Jack's Classic 20-20-20 All Purpose Water-Soluble Fertilizer, 4lb
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A balanced formula covers a first season. Mix at the label rate or weaker; more is not faster.
Weekly measurements are how you track growth and estimate weight without a scale. A standard 60-inch sewing tape is too short once the pumpkin passes about 100 pounds.
GDMINLO 2 Pack Sewing Tape Measure120Inch/300cmDouble-Scale Soft Tape Measuring Body Weight Loss Medical Body Measurement Sewing Tailor Cloth Ruler Dressmaker Flexible Ruler Tape Measure (Black)
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Wisdompro 120" Soft Tape Measure for Sewing, Cloth, Body Measuring, Yellow
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Choose a flexible fiberglass or cloth tape. A steel tape will not follow the curve and can scratch the skin.
The giant tomato class is the easiest second entry: the plants fit in a corner of the patch and use the same pots, mix and fertilizer.
Big Zac Tomato Seeds (20+ Seeds) | Non GMO | Vegetable Fruit Herb Flower Seeds for Planting | Home Garden Greenhouse Pack
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50+ Mortgage Lifter Tomato Seeds- Heirloom Variety- by Ohio Heirloom Seeds
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The Delicious Giant Beefsteak Tomato Seeds (Solanum lycopersicum)– 50+ Heirloom Non-GMO Seeds by Isla’s Garden Seeds, Can Grow to 1 Pound! Indeterminate 85–95 Days, Large Meaty Slicer, Summer Favorite
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Look for a large beefsteak type that lists fruit of 2 pounds or more. Start it four weeks before the pumpkin.
Show entries are judged clean, and a stiff brush or a fingernail marks the skin. A soft brush lifts dried soil without scuffing.
Aodaer Vegetable Brush Potato Scrubber Brush Silicone Hard and Soft Side Fruit Cleaning Tools for Delicate or Tough-Skinned Vegetables
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MR.SIGA Fruit and Vegetable Cleaning Brush with Non Slip Comfortable Grip
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Brush dry soil off first, then wipe with a damp cloth.
A 300-pound pumpkin has nothing to grip and cracks if it is rolled or dragged. A tarp with a handle at each corner lets four people carry it to a truck.
Bosmere Yard Waste Tarp, Heavy Duty Garden Tarp with Reinforced Corner Handles, UV Resistant Coating, 84-inch x 84-inch, Green
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Allsop Home & Garden 31586 Clean-Up Canvas Super Duty Tarp with Interlocking Handles of 300 lb Capacity for Garden and Yard Waste
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Buy it in September, once you know the pumpkin's size. Check the rated capacity against your estimated weight, and treat a yard tarp with no stated rating as good for a couple of hundred pounds at most. Past about 400 pounds you need a lifting ring and a tractor or hoist instead.
