Southdown Plantation was founded in 1828 by Stephen Minor, former secretary to the Spanish Governor of Louisiana, Manuel Gayoso de Lemos. The land had first been a Spanish land grant and was later owned by brothers Jim and Rezin Bowie, who began planting and harvesting indigo there. Minor purchased the land, approximately 1,020 acres, together with James Dinsmore. In 1831, sugarcane became the principle crop, and the first sugar mill was built in 1846. By 1852, Southdown was home to 233 slaves, most of whom lived in family units on the property.
The first plantation house was built by Minor's son, William J. Minor, in 1858, and was named for a breed of sheep that the family raised. The house was built of hand-fired brick and wood from cypress and pine trees that grow in the area.
The original one-story brick home was expanded in 1893, when a second story and Virginia style colonnaded walkways were added. In the same year, Favrile glass panels depicting the plantation, palmetto leaves, magnolia branches, and sugar cane stalks were installed in the house. The plantation consisted of over 10,000 acres of sugar cane fields, a sugar mill, and a race track. Southdown Plantation was instrumental in launching and sustaining the sugar industry in the area, ensuring the survival of the crop by developing a variety of sugar cane that was resistant to mosaic disease.
The Minor family was known for frequently entertaining guests and hosting many extravagant balls and receptions.