Loblolly pine is predominantly found on Ultisols but can grow on a wide variety of soils including Entisols, Spodosols, and Altisols. Loblolly pine is moderately tolerant of shade when young but becomes intolerant with age. It invades oldfields, clearcuts, and other disturbed sites. In the absence of fire, loblolly pine is replaced by climax hardwood forest. Flowering is initiated in the summer, and staminate and pistillate buds develop in the fall.
Buds remain dormant until the following spring when fertilization takes place.
The time of pollen release is variable and depends on springtime temperatures. Cones ripen in September and October of the second season. Seed dispersal begins in October and peaks in November.