• Topics: Environmental Horticulture  | Landscapes and Drought  | Residential Sprinkler Systems  |  Landscapes and Water Conservation  |  Knox, Gary W 

Coping with Drought in the Landscape¹

For a PowerPoint presentation on Coping with Drought, visit http://edis.ifas.ufl.edu/media/MG026/MG02600.ppt

Drought is likely to occur in every part of Florida at one time or another. Increased urbanization and a limited water supply predispose much of the state to a greater chance of water shortages. Because of Florida's sandy or shallow soils, drought-sensitive plants may experience drought stress after only a few days without rain or irrigation. During a drought, or when conditions indicate a drought may be imminent, the water management districts have the authority to restrict water use. The restrictions are designed to be equitable, but high priority is given to water use for human consumption, agriculture, and industry. Accordingly, irrigation for commercial and home landscapes may be restricted. With these limitations on water, the landscaper or homeowner must decide how best to use the limited water available for landscape irrigation. Follow irrigation restriction guidelines published by the water management district.

The following guidelines are given as suggestions for management practices during drought. Some of the recommendations should be followed as normal irrigation practices; they are included here for those individuals not already using proper water management practices, and as reminders for those who are. Further information on proper water management practices can be found in ENH-9 , Watering Your Florida Lawn; ENH-57, Improving Drought Tolerance in Your Florida Lawn; and ENH-72, Landscape Design for Water Conservation.

Water Management Practices During Drought

General Practices

Irrigation Priorities Irrigate newly installed plants and highly visible, intensively managed areas first. Drought-sensitive and wilting plants should have the highest priority. Drought-tolerant plants, such as many established trees and shrubs and Bahiagrass, may not need irrigation in the beginning stages of drought. Infrequent rains during a drought often provide enough water to keep these plants alive.

Time of Day Water early in the morning. Less water is lost to evaporation and wind drift in the morning because of cooler temperatures and less wind.

Irrigation Frequency

• Newly installed plants - Newly installed plants require frequent irrigation to become established. Recently planted shrubs and trees can survive on 2 or 3 weekly applications.

• Established trees and shrubs - Established plants typically do not require frequent irrigation. For established plants, apply enough irrigation to wet the soil at least 6 to 12 inches deep rather than light amounts that wet only the surface. Deep watering provides water to a larger portion of the root system. Deep, infrequent irrigation could also improve drought resistance by promoting deeper, more extensive root systems in some cases. Depth of watering should be six to twelve inches for turf and bedding plants, and twelve inches for perennials, shrubs, and trees. A depth of 12 inches is achieved with one inch of irrigation on a sandy soil. This depth may be shallower for clay soils or deeper for regions without soil such as portions of south Florida, including the Florida Keys.

Maintenance Examine the irrigation system and repair leaks promptly.

Weed Control Keep weeds under control; weeds steal water from plants.

Fertilization Don't fertilize or, if you do, do so with a low nitrogen fertilizer. Fertilization stimulates growth and can increase water needs.

Pesticide Application Avoid unnecessary applications of pesticides that require "watering in.''

Management Practices for Turf

Irrigation Irrigate newly installed turfgrass 2-3 times a day for the first 7-10 days, then once a day for 7 days, then every other day for another 7 days. After 30 days, water as needed. Established turf needs irrigation only after about 30% of your lawn starts to wilt. Signs of wilting include footprints that remain in the grass long after being made, a bluish-grey appearance to the lawn, and a large proportion of leaf blades that are folded in half length-wise.

Cutting Height Raise the cutting height of turf. Although taller grass uses slightly more water than shorter grass, a higher cutting height promotes deeper rooting and maintains turf quality longer.

Mowing Frequency Mow frequently enough that no more than 1/3 of the turfgrass leaf blade is removed at any one time. Under drought conditions, growth will be reduced, so frequency may be reduced.

Mower Blade Use a sharp blade when mowing. A sharp mower blade produces a cleaner cut that heals more quickly and loses less water than a cut made by a dull blade.

Management Practices for Bedding Plants, Shrubs and Trees

Mulch Add mulch to beds to reduce evaporation from soil and to moderate soil temperature, reducing stress on roots. Final depth of your mulch should be 3 to 4 inches after settling.

Irrigation Methods If possible don't use overhead sprinklers for shrub and flower beds; alternatives include hand watering, soaker hoses or flood irrigation, and use of low volume irrigation heads (shrubblers and emitters). Greater water loss can occur with overhead irrigation because of evaporation and wind drift.

Irrigation Frequency

• Newly installed shrubs – Recent (2007) research shows that shrubs planted from 3-gallon containers in central and south placeStateFlorida can be established by applying one gallon of water every other day. This regime provides for good root growth and some top growth during establishment. For north-central placeStateFlorida, shrubs can be established by applying one gallon every 4 days. Following these irrigation frequencies and volume, shrubs can be established in the landscape in 5 to 6 months. Once established, shrubs do not need to be watered unless they show signs of stress such as yellow or dropping leaves.

• Newly installed trees - Recently planted trees, up to 3 inches trunk diameter, can survive on 2 to 3 gallons irrigation per inch of trunk diameter applied to the root ball 2 to 3 times weekly. However, they grow best with more frequent irrigation until established. Establishment takes 3 to 4 months per inch trunk diameter.

• Established trees and shrubs - Extended drought can cause decline on even drought-tolerant established large trees. Irrigate established trees and shrubs only after they show signs of stress. This includes wilting leaves, a change in leaf color, yellowing leaves, or dropping leaves. Many trees and shrubs can survive drought without irrigation, providing they are well-established and were irrigated prior to the drought.

Shade Move container plants to shaded areas so that their water needs will be reduced.

Drastic Measures for Water Conservation During Drought

The following recommendations should be followed when drought is so severe and water use is so restricted that landscape plant survival is in question.

• Only irrigate bedding plant species and some turfgrass when they start to wilt. Irrigate established shrubs and trees when they show signs of water stress such as yellowing leaves or leaf drop.

• Apply water through drippers to the soil under the canopy of valuable trees every two weeks. This is especially important for large trees with damaged root systems.

• Apply chemical wetting agents to soil so that it will absorb water uniformly and prevent dry spots.

• For Bahiagrass lawns, stop irrigating and allow the grass to go dormant. Bahiagrass will turn brown, but it recovers well when irrigation resumes.

• Prune shrubs by reducing their size or thinning the canopy to reduce leaf area.

• Remove weak plants.

• Thin dense beds of plants to reduce competition among plants.

• Avoid planting shrubs and trees during dry conditions and high temperatures, which lead to higher evapotranspiration rates (typically, March through May).

References

Augustin, B. J. 1981. “Preparing Your Lawn for Drought.” OH-57, Cooperative Extension Service, University of Florida, Institute of Food and Agricultural Sciences, Gainesville, Florida.

Augustin, B. J. 1982. “Watering Your Florida Lawn.” OH-9, Cooperative Extension Service, University of Florida, Institute of Food and Agricultural Sciences, Gainesville, Florida.

Jones, H.C., C.S. Lippi and L.E. Trenholm. 2006. “Managing Your Florida Lawn Under Drought Conditions.” ENH-157, Cooperative Extension Service, University of Florida, Institute of Food and Agricultural Sciences, Gainesville, Florida.

Knox, G. W. 1988. “Landscape Design for Water Conservation.” OH-72, Cooperative Extension Service, University of Florida, Institute of Food and Agricultural Sciences, Gainesville, Florida.

Robinette, G. O. 1984. Water Conservation in Landscape Design and Management. Van Nostrand Reinhold Company Inc., New York, New York.

Sachs, R. M., T. Kretchun, and T. Mock. 1975. “Minimum Irrigation Requirements for Landscape Plants.” J. Am. Soc. Hort. Sci. 100(5): 499-502.

Scheiber, S. M., E. F.Gilman, M. Paz and K.A. Moore. 2007. “Irrigation Affects Landscape Establishment of Burford Holly, Pittosporum, and Sweet Viburnum.” HortScience 42: 344-348.

The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. For more information on obtaining other extension publications, contact your county Cooperative Extension service.

U.S. Department of Agriculture, Cooperative Extension Service, University of Florida, IFAS, Florida A. & M. University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Millie Ferrer-Chancy, Interim Dean.

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