Admit it, you are clueless as to how long you should water and when. There is no shame in that.
Recently I sat down using some math and sprinkler guy skill and came up with a starting point. I say starting point because every landscape is different. There can be many different micro-climates in one yard! So the key is to start with a simple program and adjust it over time to fit your unique landscape.
Program with July in mind. This is peak usage. This is our 100%. If you have a controller with seasonal adjust, leave it at 100 right now.
Check your battery. Make sure the time and date are correct. Is the AM/PM right?
Before we get too far let’s discuss some common terminology that can be confusing. We need to understand what a “program” is, a “zone” is, and the difference between “start time” and “run time”.
Program(s)
Virtually all modern controllers have multi-programs available, and they are labeled with letters: usually A through D. I’ve not seen more than four programs available, but I don’t doubt it’s out there. Think of a program like an mp3 playlist. The ‘songs’ on the playlist would be the zones selected for that program. Once the program starts, the zones water one after the other in sequence for the duration (run time) they are set for. A program is selected solely for its needed frequency, i.e. daily, every other day, odd/ even days, once a week, etc.
If you have a simple landscape where all zones all similar, there is no need to use any other program other than A. This is the default setting and no other action is needed before moving on to setting start and run times.
A good example of a zone needing to be on a separate program are pots and/or hanging baskets. These containers have a limited amount of soil, and are usually located in highly evaporative areas. The run times need to be short but frequent, maybe a few times per day, every day. Whereas lawn and shrub zones may only need watering twice a week. Short and frequent watering is not ideal to establish deep, healthy root zones for these plants.
Another example of a need for a separate program would be to establish new plants in one zone versus well established plants in the other zones.
Decide right now if you need two programs, and list the zones that will go in each. If you need a third program have a good argument for it- you may be needlessly complicating your life!
Program Start Time
Each program has its own start time(s) and days to water. This is where we can get into trouble! A start time is when the program begins, and each zone within the program waters in sequence. Do not confuse start time with zone run time, because programs usually have multiple starts available which may lead you to think you need to calculate the start time for each zone. This will cause the entire program to water over and over. This will lead to a huge water bill if unnoticed.
Examples of a need for a second start time
One reason to set a second start is what I mentioned previously- a container zone that needs watering more than once a day. Another good example is a sloped area where long watering can cause wasteful runoff or erosion. We’ll go into this in more detail below. A third or fourth start time, like a third or fourth program, needs a good argument for existing. Again, you may be needlessly complicating things.
Let’s pick a start time. Double-check the display to see the letter of the program you’re programming is showing. Anywhere between 3am-6am is good. There’s nothing wrong with having it come on later, if you’re keen on seeing it work when you’re awake. Watering in the early morning hours is ideal because the rate of evaporation is lowest.
Days To Water
Double-check the display to see the letter of the program you’re programming is showing. For straight forward, uncomplicated situations I like Monday Wednesday Friday. It’s got a certain symmetry and simplicity, a decent interval, and all the first letters are different to avoid confusion with abbreviation. For a second program you need to enter those days and start times separately.
Zone Run Times
Double-check the display to see the letter of the program you’re programming is showing. Let’s think about how much water per week the different zones need. We still have July on the mind. Let’s use these numbers:
Lawn-1″ per week
Shrubs– 0.75″ per week
Annuals– 1.5″ per week
Next consider the sprinkler type of each zone. Assuming your system is correctly designed, and your coverage is fairly uniform, (installed by a pro and not some drunk ), these precipitation rates are fairly common:
Fixed pattern sprays– .025 inches per minute
Rotating heads– .008 inches per minute
Drip tubing– .018 inches per minute
Now using our math skills, splitting the weekly requirement by three days we arrive at these run times:
Lawn– Sprays: 13 minutes, (1″/wk÷3= 0.33″/day÷ 0.25″ per min.= 13.2, or 13 minutes)
Rotors: 41 minutes
Shrubs: Sprays: 10 min., Rotors: 31 min., Drip: 13 min.
Annuals: Sprays: 20 min. Rotors: 1 hr., Drip: 26 min.
Now, remember how I discouraged you to enter a second start time? Let’s find out if one is necessary. Manually run the zones with the run times we’ve come up with. Watch for excessive puddling or run off. Note the time at which run off occurs. Shut the system off and time how long it takes standing water to drain into the soil. This is called the Cycle/Soak. The better controllers will have this program option. If yours doesn’t, but does have multiple start times, you can use that. Here’s how:
Cut the run times in half- add them up, add the time needed for soaking, and have Start #2 begin at that time after Start#1. For example S1 is 6am, zones 1,2,and 3 run a total of 22 minutes, need a half hour to fully drain into the soil, S2 will be at 7am.
If you need to cut your run time into thirds, use a Start time 3.
If you’re fortunate enough to have Cycle/Soak you need only enter the maximum run time before run-off and the time needed for soaking, and the controller does the rest for you. No need for different start times.
RECAP:
Remember that zones run consecutively in order. Don’t confuse numbered start times with numbered zones. You do not need to enter a start time for each zone. If you do you will get a big water bill.
The sole purpose of a different program is for a different watering frequency. If you don’t need to use a second or third program, don’t.
Seasonal Adjust
Remember that we programmed our controller for July. We obviously don’t want to turn it on in April and leave it that way until September. There is a bell curve of water need during that time. Actually its a jagged line that looks like monster teeth- there are peaks and valleys along the way with rain and sunny days. If you have Seasonal adjust you can dial the percentage once a month, i.e. APR-53%, MAY- 70%, JUN-78%, JUL-100%, AUG-83%, SEP- 57%. The preceding example is the monthly average for the Seattle area. The Weathermatic Smartline controller allows you to enter this data once and be done. All this feature does is adjust all run times by these percentages. You need not think further on the matter.
This is an excellent website that will tell you what you need daily http://www.iwms.org/. I just clicked on this and I’ve forgotten how great this website is. Try the calculator feature- it makes reading this boring blog post a waste of time!
Good luck, remember that “set it and forget it” is a dumb phrase. Get a rain sensor, pay attention to your plants, and run through your system manually once a month to look for problems.
