More than 360 species of vascular plants have been recorded at Second Marsh and upwards of 500 species are found in the general area. Two species found at the Marsh, Wild Rye (Elymus riparius) and Bushy Cinquefoil (Potentilla paradoxa) are classified as provincially rare. Several other species are regarded as regionally rare or uncommon.

Friends of Second Marsh community-based planting programs for Second Marsh and the Black/Harmony/Farewell watershed have successfully contributed to the improvement of diversity in vegetation and the overall health of the ecosystem.