Some plants, such as broadleaf evergreens, are particularly sensitive to temperature or drying winter winds. Examples of protected sites include those bordered by walls, buildings, or evergreen screens, and those where the ground changes slope. These sites offer plants protection from full exposure to harsh weather conditions. Weather conditions are often quite different in large cities compared to the surrounding countryside. Water evaporation on the leaf surface helps cool the plant during very hot weather.
Plants even require water during winter.
Water is absorbed through and stored in roots for winter. When soil is frozen, water movement is very restricted. On windy winter days, leaves of broadleaf evergreens, such as rhododendrons, may curl to reduce water loss. Curling reduces the amount of leaf surface exposed to drying winds, reducing evaporation. Continued water loss may cause tissue to die and turn brown.