The Birmingham Botanical Gardens span two level IV ecoregions within the Ridge and Valley level III ecoregion. The slightly hilly southern portion of The Gardens is within a pocket of the Southern Shale Valleys level IV ecoregion, which itself is nested within the Ridge and Valley level III ecoregion, one of the major ecoregions of the Southern Appalachian Mountains. The terrain of the Southern Shale Valleys is dominated by stream valleys and low hills predominantly of shale.
The hilly northern portion of The Gardens is within the Southern Limestone/Dolomite Valleys and Low Rolling Hills level IV ecoregion. The terrain of this ecoregion is one of karst topography interrupted occasionally by hills of chert and sandstone. Despite the ecoregion’s name, the portion of The Gardens in this ecoregion is on a foundation of sandstone.