WATERING GUILDLINES

 One of the most common questions asked to improve lawns is “How much  should I water?”. There are many variables that go into the answer to this question so I thought, as a service to my clients, I would lay out some basic guidelines for you to follow to  optimize your watering efforts. So let’s go! 

 • The amount of water you should target to apply during the growing season of lawns in  our area is 1.0”(one inch)per week. Science of enormous proportions has gone into  determining this number and I won’t bore you with that, you will just have to trust me! 

• 1.0” per week is a base line. All lawns are different so the results of 1” will be too wet or  dry for some and just right for others. Start out with 1” and adjust to meet your  property’s optimum watering needs. Too wet? Cut back on run times! Too dry? Increase  run times! 

• The first question I get when discussing this subject is, “How do I know how much is an  inch?”.  The easiest and most accurate way to measure your watering efforts is with a  rain gauge. I recommend one that stands no taller than 12” or so from the top of  the gauge to the ground. Locate the gauge in an easy to access, irrigated area of  your lawn at ground level.  Monitor the gauge every other day for the amount of water that is being applied  both by your irrigation system and natural precipitation (rain or snow).  Pick a day of the week to dump the gauge and start over.  Move the gauge to different areas of the lawn if you want to know how much  water is being applied to various areas of the lawn. Once you learn your lawns  watering habits you can stop monitoring if you like and use local weather data to  supply you with information.  (Rainfall + Irrigation)=Total Precipitation (water) Applied. 

• Another common question is, “When do I water?”.  This actually is a two part answer that includes what time of day to water and  what day(s) to water. What day(s)? Assuming there are no local water restrictions I suggest that you  water every other day with a target of .29” as your goal. In a two week period  this will net you 1” per week. What time of day? Evaporation rates are at their highest levels from around  10am to 8pm in the growing season. Avoid watering during this time as a  standard practice to avoid wasting water.  The total amount of time your system will need to complete the programmed  water cycle is your “water window”. So if the total cycle run time will require 6  hours that is your water window. That means if the cycle starts at 12am it will  finish at 6am. (Total run time for programmed cycle = water window).  I suggest that you start your cycles as late in the early morning hours as you can  but in time to finish before everybody wakes up for breakfast. If you don’t mind  water running in the morning then by all means let it run. I would target 8am as  the latest time to finish the cycle. The goal is to not leave the lawn damp any  longer than necessary before day break! o If water restrictions are in place then my suggestion is to water as much on the  day(s) allowed as you can factoring in the 1” goal. Splitting up the run time of  each zone/station will help avoid generating runoff by applying too much water at one time. The lawn and golf course industry used a practice called “Cycle and  Soak”. Cycle and soak is basically splitting up the targeted run time of a zone into  multiple short time cycles and placing a soak time in-between each cycle. For  example, say your target run time is 30 minutes for a zone. Running the zone for  10 minutes, 3x, will accomplish the same goal. Placing a soak time of 30 minutes  in-between each 10 min cycle will allow each cycle’s applied water to soak into  the soil without generating runoff and wasting water.  

• Irrigation Products – There are basically 4 standard types of irrigation  devices/methods/products used on the market today: Spray, Rotor, Rotary Nozzles and  Drip. They are very different in how they apply water and it is important to know what  product you are using.  

  ~ Sprays are used in smaller spaces of lawns. They are typically space 10-15’ apart.  

  ~ Rotors are typically used in large space of a lawn and are typically spaced 30-50 ft  apart.  

 ~  Rotary Nozzles are designed to replace spray nozzles with a touted 30% more efficient   water delivery than sprays. Like sprays they are typically spaced 10-15’. 

 ~ Drip irrigation is commonly used in flower beds and medians/strip found  between streets and sidewalks. They deliver water through a pvc tube that has  water emitters placed every foot or so. Water drips from the tube and soaks the  soil! 

 • Soil Infiltration Rates: The rate at which soil receives water is known as the “water  infiltration rate”(WIR). Sand can have WIRs of 50+ inches per hour. Clay can be 0.5  inches per hour! Applying water at a rate faster than the soil can receive it will produce  wasteful run off. Sloped areas will generate run off faster than flat areas. The point at  which a zone’s runtime generates runoff is the maximum efficient run time for that  zone. Ideally the zone would shut off a minute or two before runoff is generated. The  cycle/soak technique mentioned earlier is an excellent way to avoid exceeding your  WIR. 

• Water Evaporation: Water evaporation/consumption in a lawn is also referred to as  “evapotranspiration” or ET. ET factors in air flow, temperature, soil type, grass type, humidity and light intensity to compute the use/loss of water in a given day. If the ET of  a given day is .3” that theoretically means you/nature needs to replace that amount of  water. ET levels also are totaled as a week evolves so two days with an ET of .3” means  you are behind .6”. Local ET values can be found online at http://texaset.tamu.edu/! 

• Closing: Proper watering of you lawn does not happen without someone in the  household being engaged with the subject to insure what’s suppose to be happening is  happening. I hope you will find these guidelines helpful. My plan is to add more as I  recall them and think they are relevant to the subject. 

Please feel free to email or text  me if you would like more guidance or information! Many thanks for your patronage! 

Chris