Competitive growers choose from among heirloom and F1 hybrid tomato varieties that possess an indeterminate plant habit (since big plants nurture the growth of big fruits) and the right genetics.
There are scores of varieties that will produce tomatoes weighing 1, 2, or even 3 pounds. Fewer yield fruits weighing in the 4-to-6-pound range. Two varieties—‘Delicious’ and ‘Big Zac OP’—are capable of producing 7-pounders.
I remember the excitement and hoopla when Gordon Graham of Edmond, Oklahoma, set a new world record in 1986 for growing the heaviest tomato. The prize fruit was the 7 3⁄4 pound ‘Delicious’. Key to success was technique and the right germplasm (seeds): Burpee’s ‘Delicious’, bred in 1964 after 13 years of intensive breeding and selection from the heirloom ‘Beefsteak’ (‘Crimson Cushion’). Luck was also on Graham’s side: Winds felled the sizeable plant onto his cantaloupe patch, where a singular tomato grew undisturbed to enormous proportions.
After 27 years, Graham’s record-breaking tomato has yet to be beat. But it’s not for lack of trying. The arena is crowded with sophisticated heavy hitters, yet only a handful have come within a pound of the goal in recent years. Utah tomato grower Dale Thurber is compiling competition statistics from around the world for all the largest tomato varieties. He says with confidence, “I expect to see a 10-pounder in my lifetime.” He’s 50 years old. I hope he’s right.
But it may become increasingly difficult in future to top Graham’s record significantly. High temperatures, particularly nighttime temps over 70°F, are apparently creating fruit-set problems across the country, and bigger-fruited varieties seem to be most vulnerable, according to seedsman and pollination expert Jeff McCormack at Saving Our Seeds. Tomato meister Marvin Meisner, author of the classic Giant Tomatoes (2007), adds that even if fruit set is successful, “high temperatures during the tomato-growing phase result in smaller tomatoes” because the warmth speeds ripening. We’ll have to adapt our varieties and technique—or start competing for the world’s tiniest tomato.