This study was conducted for the development new outdoor garden materials through the evaluation of adaptability to outdoor environmental conditions (drought and salinity stresses) targeting four native grasses in Korea. The plant materials for the experiment selected four native grasses with excellent ornamental value and high potential for use in the garden: Melica grandiflora Koidz. (Poaceae), Carex forficula Franch. & Sav., Schoenoplectiella mucronata (L.) J.Jung & H.K.Choi, and Carex boottiana Hook. & Arn. (Cyperaceae). The drought stress was carried out according to the irrigation cycle: well-watered (WW, once every 72 hours), moderate drought stress (MD, once every 336 hours), and severe drought stress (SD, no irrigation for 30 days). The salinity stress was carried out according to NaCl concentration (mM): untreated (UT), moderate salinity stress (MS, 250 mM NaCl), and severe salinity stress (SS, 500 mM NaCl). The experiments were conducted from June to July 2023 in the Sejong National Arboretum greenhouse and analyzed the physiological and biochemical characteristics of each species. The Pn of all four native grasses significantly decreased according to increased drought and salinity stress levels after 30 DAE. Especially, altering the structure of the canopy by altering its length and width in C. boottiana showed little change in SD and SS compared to WW and UT, although the Pn showed low tendencies in. In drought treatments, Chl. T. and Carotenoid M. grandiflora, and C. forficula under SD were significantly lower than those under WW. On the other hand, C. boottiana had no pronounced differences under drought treatment levels. In salinity treatments, Chl. T and carotenoid were gradually decreased for three species, except for C. boottiana, according to increasing the salt concentration. The MDA content of M. grandiflora and C. forficula strongly enhanced according to increasing drought and salinity stresses. The O2 - content of tree species except C. boottiana was significantly increased according to drought and salinity stress. Therefore, C. boottiana has high resistance to drought and salinity stresses and is expected to be highly utilized as a sustainable outdoor garden material to combat climate change.