Floristic Quality Assessments (FQAs) are used as indices of ecosystem quality and typically consist of two parts, a species checklist and each species’ coefficient of conservatism, or c-value. Tennessee and Kentucky (TNKY) share most native and naturalized vascular plant species and ecoregions, putting TNKY in position for combined c-value assignment. Previously, two TNKY botanists created individual draft c-value assignments for TNKY’s flora. One assigned c-values to 100% of the documented vascular plant species of the states of Kentucky and Tennessee at the time the work was performed and the other to 98%; thus, these two botanists overlapped on assigning c-values to 98% of the TNKY flora. Two previous attempts by Shaw assembled panels of TNKY botanists for c-value assignment. Although neither attempt resulted in statewide c-values, these twelve botanists assigned c-values to 35% of TNKY’s flora. Additionally, we used two existing databases, (43% and 76% of TNKY’s flora, respectively), each treated as “a botanist,” to assemble a “panel of experts.” Although using a panel to assign c-values is most common, here we show that using a combination of a botanist panel and supplemental databases is an effective means of c-value assignment. We conducted statistical analyses to test correlation of botanists’ c-value assignments and TNKY’s native c-value data against the floras of six surrounding states, and we held a public review period of three months. Overall, c-values were successfully assigned to 99% of TNKY’s flora (3,360 species).