The native flora of Saskatchewan includes vascular plants, plus additional species of other plants and plant-like organisms such as algae, lichens and other fungi, and mosses. Non-native species of plants are recorded as established outside of cultivation in Saskatchewan, of these some non-native species remain beneficial for gardening, and agriculture, where others have become invasive, noxious weeds. Saskatchewan is committed to protecting species at risk in Canada. The growing season has been studied and classified into plant hardiness zones depending on length of growing season and climatic conditions. Biogeographic factors have also been divided into vegetative zones, floristic kingdoms, hardiness zones and ecoregions across Saskatchewan, and natural vegetation varies depending on elevation, moisture, soil type landforms, and weather. The study of ethnobotany uncovers the interrelation between humans and plants and the various ways people have used plants for economic reasons, food, medicine and technological developments. The Government of Saskatchewan has declared 3 indigenous plants as provincial symbols.

Saskatchewan possesses a continental climate and the seasonal variations in temperature provide a short growing season. On average the province supports 159 to 160 frost-free days, in the far north that number diminishes to 85 to 95 frost free days. In 1967, Canadian scientists created a map outlining Plant Hardiness Zones. The hardiness zones examine climatic gradations such as length of frost-free period, summer rainfall, maximum summer temperatures, minimum winter temperatures, and wind speed. The harshest plant environment is 0 and the mildest is rated as 8. Corresponding data was correlated for plant requirements. Such an examination provides direction to which flora may survive the geographical hardiness zone conditions. A development in the late 1800s encouraged homesteaders to pursue agriculture. Red Fife wheat (Triticum aestivum) matured 20 days before other wheats, which allowed plants to ripen before the autumn frost.

Saskatchewan has 367 rare species of vascular plants of which 135 of these have been listed as endangered.

There is listed Small White Lady's Slipper (Cypripedium candidum) as the only local extinction, (extirpated) plant. Endangered plants include the Sand Verbena (Abronia micrantha), Western Spiderwort (Tradescantia occidentalis), Tiny Cryptantha (Cryptantha minima), and Hairy Prairie-Clover (Dalea villosa). Threatened plants include the Slender Mouse-Ear Cress (Halimolobos virgata). These two reports to aid in the protection of plants; Species at Risk In SK and Rare Plant Survey Guidelines. Saskatchewan has implemented The Weed Control Act to control plants introduced to Saskatchewan which have become a threat to the natural biodiversity such as leafy spurge (Euphorbia esula). There are two reports in this regard; Invasive Species and Noxious Weeds of Saskatchewan.

Saskatchewan's commitment to the Accord for the Protection of Species at Risk in Canada, which was ratified by provinces, territories and the federal government in September of 1998,"

Section 15 (1) of the Act states: "Every owner or occupant of land shall:

(a) under the supervision of the weed inspector, eradicate any prohibited weeds located on the land;

(b) under the supervision of the weed inspector, eradicate any isolated infestations of noxious weeds located on the land;