AbstractRed light with a wavelength of 660 nm promotes germination of longleaf pine (Pinus palustrisMill.) seeds, and far‐red light (730 nm) inhibits germination. The promotion‐inhibition process is repeatedly reversible, indicating that germination is controlled by the photoreversible reaction of phytochrome. Response varied greatly between single‐tree lots and was dependent on the length of time seeds were imbibed at 5°C. Dry seeds did not respond to light treatments when they were subsequently imbibed and tested in darkness. Stratification for 28 days essentially removed the light requirements for germi