Geesje Mesdag-van Calcar received her art education at the Minerva Academy in Groningen, which she completed with an internship with P.J.C. Gabriel. She married fellow painter Taco Mesdag (1829-1902), brother of the well-known Hague School painter Hendrik Willem Mesdag. After their marriage they moved from Groningen to The Hague, where they became members of the artists' society Pulchri Studio. Geesje regularly exhibited and devoted herself to other female artists. She painted flowers, landscapes, still lifes and interiors, in an impressionistic style. In the summer the Mesdag-van Calcars worked in Vries in Drenthe, where they had a farm with a studio. Later Geesje went to Kortenhoef, where she had a studio built on stilts and painted polder landscapes.