The native wetland plants that produce cranberries start growing in May. When they are ready to be harvested, farmers flood their bogs with water and send out a picking machine to shake the berries from the vines. Then more water is added to the bog, and the freed cranberries float to the surface.

Weeks before Thanksgiving, some of the cranberries on dinner plates Thursday are floating on the Rocky Meadow bog in southeastern Massachusetts. The cranberries have turned this pond pinkish crimson.