What Are The Irrigation Requirements For Turfgrass And Landscape Plants?
Note: The term “irrigation requirements” implies well-watered conditions, which means that this is the amount of irrigation water in addition to effective rainfall (that which is stored in the plant root zone and available for use) needed for plant growth and without any water stress. Ornamentals: All landscape shrubs and trees grown in a nursery and planted in a landscape require water to become established. Under most circumstances, rainfall occurs irregularly, so irrigation is required, at least until plants are established. Trees require about three to four months per inch of caliper (trunk diameter measured 6" from ground) to become established. Irrigation events should be 2 to 3 gallons of water per inch trunk diameter. For example, a 2-inch tree should be watered 4 to 6 gallons at each irrigation event. Water every other day until plants are established. In addition to initial watering for establishment, irrigation in the year following establishment may be needed to maintain good quality in dry weather. We have little data on irrigation requirements for plants once established, due to the many factors that influence this. These factors include slope, aspect, soil compaction, soil depth, soil volume, width of soil space, depth to water table, wind, season, size of plant at planting, nursery production method, length of time in the container, and root pruning strategies at planting. This research simply has not been done. Turf: Under well-watered conditions, Stewart and Mills (1967) reported that annual water consumption in South Florida for St. Augustinegrass and bermudagrass averaged 43 inches/yr over five years. For North Florida, Jia et al. (2007) reported 33 inches of total water requirements for bahiagrass. Irrigation requirements for turfgrass in North Florida are on the order of 20–25 inches/yr and 30–35 inches/yr in South Florida, on average (Smajstrla, 1990). These numbers are net irrigation requirements and do not include added irrigation due to the inefficiency inherent in all irrigation systems. See “Efficiencies of Florida Agricultural Irrigation Systems, ” for more information on irrigation efficiency (Smajstrla et al., 1991). In most years, rainfall will contribute substantially to meeting the total water demand of turfgrasses.
