People have been growing flax for thousands of years, in many different parts of the world. In ancient Egypt, planting times were governed by the seasonal floods of the Nile. In Western Europe, flax was planted in the spring, and yet, in the Himalayas and Alps, oral legend tells that flax was sewn in the fall, at the same time as barley. China, India, the Middle East, Japan, Africa, and later North America, all had different planting times.
Grown around the world for thousands of years, flax was sown in different seasons. In ancient Egypt, the Nile's seasonal floods governed when to plant. Western Europeans planted flax in the spring, yet oral legends recount that growers in the Himalayas and Alps planted flax in the fall, alongside barley. Growers around the world planted flax in the right season for their climate. The term "towhead" comes from the word for flax or hemp fibers and their resemblance to white blond hair.
Of course the first sentence is passive voice, but it works (and spells "sown" correctly).