Water is essential for plant growth and moves through plants via osmosis from areas of high water potential in the soil to areas of low water potential in leaves. It travels upward through the xylem via cohesion and adhesion. Transpiration pulls water through the plant and increases with temperature, sunlight and low humidity. Plants have adapted mechanisms like waxy coatings to reduce water loss. In soil, water exists in gravitational, capillary and hydroscopic forms. Clay soils retain more water but drain less well than sandy soils. Proper irrigation requires determining plant water needs based on evapotranspiration and soil type, and regularly checking penetration depth and application rates. Watering in the morning is best to reduce evaporation.