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Straight Answers on Water for the St. Augustine Lawn

 (See also recommended links below)
also visit Pumping Capacity Calculator and Wind and Turf
  Cup Catchment Test for turf irrigation distribution uniformity and precipitation rate
  Cup catchment is the way to determine irrigation uniformity and precipitation rate.  It should be done for a timed duration under typical wind speeds and with numerous cups.

Q: How little water does it take to keep St. Augustinegrass alive?
A: Very little, about 43 inches per year, which is much less
than the 60 inches we get in rain.  ("Water requirement for St. Augustinegrass")

Q: So what's the problem?
A: In South Florida, from March to May, there's less rain each month than the turf needs to stay green.

Q: How much water does it take to keep St. Augustinegrass green?
A: In a typical year the lawn needs about 3, 4, and 6 irrigation events in March, April, and May, at 3/4 inch each. If it doesn't rain a drop, the turf needs about 5, 6, and 7 irrigation events, respectively. The rest of the year the lawn can get by with 2 irrigations per month because there's plenty of rain, and in December and January it's cool enough that we might not need to water at all.

Q: Is this true everywhere?

A: No. This is based on well drained level areas near the water table. In urbanized Miami-Dade and Broward Counties, the water table averages 4.5 feet depth, which is close enough for some moisture to wick up through the rock to the turf roots. Some areas are wetter or more protected by shade, while the coastal ridges, hill mounds, and areas near the pavement and near the prevailing winds tend to dry out faster.  ("Contour of water elevation")

Q: If the turf doesn't get watered, will it die?
A: Yes, eventually St. Augustinegrass will die. Let's say it doesn't rain a drop, and the turf starts to wilt in the late afternoon, but it looks okay in the morning. ("Killing the lawn").  Within about 7 days the turf will continue to be wilted in the afternoon, but when you look at it in the morning, it hasn't recovered, and it's remained wilted all night and all the next day. Now you've got about 7 days before the lawn is dead brown.

Q: Only fourteen days doesn't sound very safe.
A: It's very likely that there will be some rain.

Q: What about spraying the turf with an antitranspirant or putting some superflexology geewhizmo polymeric soil body conditioner to the soil?
A: It's your money. Why don't you just put the money in the soil? More seriously, plants have been at the business of growing for several hundred millions of years. They haven't figured out how to grow and exchange carbon dioxide without losing water at a comparable rate. Those two compounds have the same diffusion properties, and there are no synthetic materials that can change the basic physics. Also, the turfgrass has essentially no internal resistance to water exchange. It acts as a soda straw, driven to lose water based on the heat energy from the sun. When you heat a pot of water, the water converts to a gas. When the sun shines on the leaf, the water converts to a gas. Same process.  ("Drought Resistance and Landscape Water Conservation")

Q: What about the irrigation system? If we only have a few hours per week to irrigate, shouldn't we make those hours count?
A: Right. Irrigation systems tend to be poor in distribution, and this is corrupted by wind. A thorough audit of your sprinkler system will reveal some things you can improve. Also, Try not to water when the wind is blowing strong, say, more than about 5 miles per hour.  ("Coping with Watering Restrictions")

Recommended irrigation links:

Fix your sprinkler system . . . so you can shut it off!

Valve boxes http://www.floridaturf.com/valvebo.htm

How not to ditch

Water requirement for St. Augustinegrass (part 1 of 2): How much?


Water (part 2 of 2) Killing the lawn"
This two-part series describes the normal process of water use by turfgrass, and how many days it takes to kill a lawn by not watering it.

Irrigation Conservation in Best Management Practices (BMPs)

An Opinion Essay
http://c-11.org/drought/ Basically, you can't have your cake and eat it, too. An attempt to dispel common irrigation myths. With associated slide show:

Lots of water but seasonal drought http://c-11.org/landscape/ A photo-illustrated guide

Guides and articles:

Jess Stryker's Free Irrigation Tutorials!   Many excellent articles on irrigation.

Irrigation Industry Links

WWW-Virtual Library IRRIGATION. Quite a few good links.

Efficiencies of Irrigation Systems Used in Florida Nurseries.

Sprinkler Irrigation Uniformity - Center for Irrigation Technology Irrigation Notes.

Irrigation Systems Slideshow - New Mexico State University.


The Irrigation Association. The national trade association.  There is a directory of certified installers.

Irrigation & Green Industry Network.  Go to the irrigation section for information.

Texas Turf Irrigation Association Code of Ethics - some great ideas.

Design software:

Software Republic Landscape design software and irrigation design software. RainCAD appears to be a useful program; shareware downloads.

Manufacturers and suppliers:

Rain Bird - Irrigation Manufacturers, Sprinklers, Products, Landscape Systems  Rainbird is one of the other major manufacturers

Spears Manufacturing Co. Plastic pipe fittings and valves.

SprinklerSpot - purchase online.

TORO: Golf Course Management. Toro's main irrigation page

Toro Residential / Commercial Irrigation. Toro's landscape irrigation pages.

Weathermatic - Homeowner information, but no retail sales.

Turf Bubbler Wick Irrigation -- The Evolution Begins!   An example of an alternative system, which is neither subsurface nor overhead.

Valve Boxes, Valvebox, Irrigation Valve Box, Meter Boxes, Electrical Boxes Made By AEP Valvebox. Valve boxes are one of the often-overlooked essentials.

Weathermiser - not a time clock, "not rocket science, or maybe it is."  Device upgrades existing sprinkler timer to adjust for relative humidity, wind, and temperature.  Like a miniature weather station but apparently does not measure rainfall.


Barry Edwards Irrigation - excellent photos of installations.

Books on Irrigation:

Choate, Richard B. 1994. Turf Irrigation Manual. Weather-matic Division of TELSCO INDUSTRIES, Dallas, TX.

Pair, Claude H. (ed.) 1983. Irrigation. The Irrigation Association. Arlington, VA.

Pira, E. S. 1997. A guide to golf course irrigation system design and drainage. Ann Arbor Press, Inc. Chelsea, MI.

Sarsfield, A. C. 1966. The abc's of lawn sprinkler systems. Irrigation technical services. Lafayette, CA.






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