Sunflowers sprout in a carefree manner all over the world. Pollinated by bees, the plants spring up on the sides of highways, under bird feeders, and across fields, meadows, and prairies. To produce a harvest, however, sunflowers need good soil. Well-drained, slightly acidic, nutrient-rich soil “with organic matter or composted,” says the Farmer’s Almanac, finally produces tasty sunflower seeds, pure oil, and also a livelihood for hard-working sunflower growers...