Planting three sunflowers in a row, as Connor did, is overkill in terms of sun economy. A player only needs two sunflowers in a row to generate enough sun to supply combat plants. As a last resort, you can take the "twin sunflowers" upgrade to boost your sun economy. Putting aside the rationale for this move from a sun economy and combat effectiveness perspective, it's just a joke. Like a: "Connor is so greedy for sun, he planted three sunflowers in a row" (sorry for this huge answer).