Can you incorporate three Loblolly pines into a larger berm? How far apart do Loblolly pines need to be planted?
Considering these trees when mature can top 115 ft, and have a characteristic broad sweep of branches. Leave 15-20 feet between the trees. It will allow for both their size and for good air circulation as they mature. It makes them much less susceptible to disease. It will also allow you better access if you should need to treat them for insect damage or disease as they mature.