Great Blue Herons nest in colonies, though occasionally will nest as lone pairs. The nest is a large platform, up to four feet in diameter, built from twigs and branches and lined with pine needles, moss, reeds or dry grass. Nests are usually built high in trees, though occasionally are placed on the ground on islands.
Both adults incubate a clutch of 2 to 6 pale blue eggs for about 27 days. Chicks will fledge between 52 to 80 days after hatching.