Marigold (Tagetes erecta), besides being an ornamental plant, has various medicinal properties—it is nematocidal, fungicidal, antibacterial and insecticidal and aids in wound healing. Our work is focused on the blood clotting activity of its leaf extracts. Extraction was done by conventional as well as the Soxhlet method, which was found to be much more efficient using a 1:1 ratio of ethanol to water as solvent. Blood clotting activity of the leaf extract was examined using prothrombin time test using the Owren method. For both extraction methods, the yield percentage and coagulation activity in terms of coagulation time were analysed. Marigold leaf extract obtained using the Soxhlet method has shown very good blood coagulation properties in lower quantities—in the range of microlitres. Further research is needed for identification and quantification of its bioactive compounds, which could be purified further and encapsulated. Since marigold leaf has antibacterial properties too, therefore, it might be possible in the future to develop an antiseptic with blood coagulation activity.