Female plaice start to spawn at approximately 11 years of age (about 45 cm in length). Males become sexually mature anywhere between three to six years of age (about 40-45 cm), depending on where they are, geographically.

Plaice spawn between April and June. Spawning and fertilization of the eggs occur near the bottom of the ocean. Once fertilized, the eggs float to the surface layer where hatching occurs. Hatching time is variable, dependent on water temperature and depth. The larvae and juvenile fish reside closer to the surface of the water and may drift a considerable distance before the young fish finally settle to the bottom. Juvenile plaice have a round body with eyes on both sides of the head, until they sink to the bottom of the ocean and morph into their flat, adult body shape.