Eric, I wasn't describing something that happens in the ocean, which is a different environment, or in the presence/absence of sunlight. If you don't want to believe me, how about the Encyclopedia Britannica?

https://www.britannica.com/topic/growing-season

"Growing season, also called Frost-free Season, period of the year during which growing conditions for indigenous vegetation and cultivated crops are most favourable. It usually becomes shorter as distance from the Equator increases. In equatorial and tropical regions the growing season ordinarily lasts all year, whereas in higher latitudes, e.g., the tundra, it may last as little as two months or less. Growing season also varies according to elevation above sea level, with higher elevations tending to have shorter growing seasons."

This definition completely contradicts your "length of day" theory.