First, seed thieves gutted Big Bertha. Then, in two other incidents, they stole her 16 "sisters."

Joyce Trimingham knows to what lengths people will go to get giant pumpkins like Big Bertha and their seeds.

"Never, never, never could I have imagined this," the 78-year-old gardener said Sunday. "But these are difficult times. If somebody could make a few bucks on something, they will. There's a lot of strange people in this world."

Gnarly and strangely shaped, giant pumpkins – weighing hundreds of pounds – have become a huge part of Halloween celebrations nationwide. In just seven years, official weigh-offs have nearly quadrupled to 92 as pumpkin mania prompts gardeners to grow big.

Although heft can win prize money, their value doesn't come from their pulp; it's used for livestock feed or composted. The seeds are what sells.

Trimingham suspects that's what prompted the initial incident in the Faith Community Church garden in south Sacramento's Parkway Estates. In her plot, she grew Dill's Atlantic Giant pumpkins this year as prizes for a community raffle.

But before she could pick her pumpkins, someone cut a hole in a 250-pounder nicknamed Big Bertha, and scooped out its precious seeds. Shortly afterward, two more huge pumpkins went missing.

As a final blow, thieves carted off 14 more pumpkins, leaving her garden bare and raffle winners empty-handed.

"It had to be at least two thieves; one person couldn't carry them," she said of her missing ton of pumpkins. "Someone must have been watching them."

What would they do with all those oversized pumpkins? They didn't make pie. These mammoths often end up smashed, exploded, catapulted or dropped as Halloween stunts. Or they get carved and adored by Halloween revelers.

At Cool Patch Pumpkins in Dixon, Matt and Mark Cooley recently walloped a Honda with a 1,000-pound pumpkin for a Halloween TV special on the Travel Channel. They blew up another 1,000-pounder at Travis Air Force Base.

"It went really well," Mark Cooley said of the explosion. "It was a lot of fun. They really enjoyed it."

The Cooleys – who grow thousands of pumpkins – don't save their seeds.

"They're hybrids," said Cooley, noting that their offspring could be totally different from the parent pumpkin. "You don't know what you'll get. We like to start with clean seed; then we'll know exactly what we have."

California ranks as the nation's No. 2 pumpkin producer, behind Illinois, according to the U.S. Department of Agriculture. The 2010 California crop totaled 186 million pounds.

This was a "phenomenal" pumpkin year, Cooley added, with warm, dry fall weather, allowing the big ones to mature.

Earlier this month, Half Moon Bay's 38th annual World Championship Pumpkin Weigh-Off crowned another champion while handing out $25,000 in prize money. A pumpkin grown by Leonardo Urena of Napa crushed the scale at 1,704 pounds, a California record.

Urena's champion pumpkin was shipped 3,000 miles to be displayed at the New York Botanical Garden's Halloween showcase of colossal squash. That included the new world record holder, a Canadian giant weighing 1,818.5 pounds.

Urena also was named "Grower of the Year" by the Great Pumpkin Commonwealth, an international group devoted to growing giants. This year, Urena grew a trio of pumpkins weighing a combined 5,000 pounds.

In pursuit of the first 1-ton pumpkin, commonwealth members trade seed for free.

"It's supposed to be a hobby, not about the money," Urena told reporters after the weigh-in. "To sell one of my pumpkins' seeds would be dishonorable to the pumpkin world."

Most pumpkins contain between 100 and 700 seeds, according to growers. Giants often have far fewer seeds than their comparatively teeny counterparts. (That's the moral of Margaret McNamara's children's book, "How Many Seeds in a Pumpkin?")

The early giants came from breeding 50-pound blue-green hubbard squash with pumpkinlike kabocha squash, which usually weigh under 5 pounds. In part because of this heritage, most giants lack the classic pumpkin color or shape.

Today's best-known giants come from strains developed by Howard Dill, a Nova Scotia farmer who grew the first 500-pounder in 1981. Dill's family farm continues to cultivate mammoth pumpkins and, via its website (HowardDill.com), sells the coveted seed online worldwide for as much as $20 each.

Last year, a single seed from the then-world record 1,810-pound pumpkin sold for $1,600.

For her pumpkin patch, Trimingham planted Dill's Atlantic Giant and got 17 pumpkins to reach maturity.

Although thieves wiped out her harvest, Trimingham hasn't given up hope. A neighbor of her son, Jim Trimingham of Elk Grove, grew a 900-pounder for Elk Grove's annual pumpkin festival and gave seeds from his behemoth to the Triminghams.

"After what happened, I took a deep breath and decided I'll try again next year," she said. "They needed a flatbed truck to haul that 900-pounder to the contest. I'm going to go for it. I can just picture it, growing in my garden."

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