Advice for WATERING
Residential LAWNS and Landscaping

In Colorado, proper watering with an automatic sprinkler system will have the greatest positive effect on your lawn than anything else that you can do.  After watering, I believe organic fertilizer is the second-most important aspect of maintaining a healthy lawn. Finally, how you mow your lawn will make a big impact.  This article will focus on best practices for efficient watering of your lawn in Colorado. Before developing a watering plan, check to see if your municipality has watering restrictions in place.  In Lafayette, you may not water between the hours of 10:00am and 6:00pm. This is not a problem for most homeowners because it is better to water in the early morning, and an automatic sprinkler system will do just that.

A word about sprinkler systems:  If you have an automatic sprinkler system, it must be winterized every fall to avoid freezing and cracking the copper and brass plumbing and back-flow preventer that feed water to your system.  The average last freeze date for Denver around May 15, that means the last hard freeze that could break your system is usually mid-April.  I suggest waiting until at least May 1 to start your sprinkler system.  The average first freeze date for Denver is around October 15, and the first hard freeze is usually not until after October 30, to be safe, try to have your sprinkler system winterized by October 1.

New Sod:  If you have new Sod, it will need lots of water during the first 4-6 weeks. The rule of thumb is to keep it damp so that it does not dry out. Sod watering is highly dependent on weather – the average need is about 5 minutes in the morning, and another 5 minutes in the afternoon. Watering restrictions may force you to hand-water sod during the day until it is established.

Principles of watering: Deep watering (6-12″) and less frequent watering (every 3-7 days) is the only way to achieve a super healthy lawn and conserve water at the same time.  Deep watering improves plant health because the grass roots  “chase”  the water down.  As your deeply watered lawn dries out, water is percolating deeper into the soil, and grass roots are chasing the water down, effectively aerating your soil – and eventually eliminating the need for aeration. The principle of deep and infrequent watering allows the lawn’s roots to dry out in between waterings, and this is critical to preventing diseases that thrive in the humid areas of your lawn.  In Colorado, established lawns should be watered no more than every 3 days.  If you put your mind to it, a healthy lawn can be watered as infrequently as every 5-7 days. A deep root system is essential to a drought-resistant, disease resistant, water-efficient, weed-choking, green lawn and the key to deep roots is deep and infrequent watering. The easiest way to see how deep the roots of your lawn are is to check the soil; push a spade down into your lawn and look; the deeper the better.  If your spade will not penetrate the soil, your lawn is too dry. If you have been watering every day, you will find the grass is green on top but your lawn’s roots are shallow because they cannot grow in the mud underneath, and you will almost always see disease in a lawn that is not allowed to dry out in between waterings.

Timer Settings: Using a cyclic or interval setting on your timer is more efficient than picking days of week although sometimes, this is not an option (such as when mandatory watering restrictions dictate specific days of the week for watering, or your timer does not offer this function).  Although I often start with every 3 or 4 days, it is possible, over time, to water as infrequently as every 5 days or more.  Watering your lawn at night will reduce evaporation and save water so we usually set watering times to end by 6:00 am.  To do this, figure the longest run times you will need during the heat of the summer and work backwards.   Example: if you will be watering for a total of 4 hours in July and August, start at 2:00 AM so you will be done by 6:00 AM.  I usually set timers to start at 12:00 am, and this usually provides enough time to get all the watering done before the sun comes up.  Water application rate is crucial for clay soils.  If you water your lawn all at once, the soil will not absorb the water fast enough, causing run-off.  Address this problem by breaking up your zone watering time with soaking time.  Instead of starting program A at 12:00 AM, and watering zone 1 for 30 minutes, zone 2 for 30 minutes, and zone 3 for 30 minutes, break each 30 minute zone watering time into 3 separate 10 minute watering times by setting three start times for each zone and setting the zone run time to 10 minutes, like this: Program A, start time #1: 12:00 AM, start time #2: 2AM, start time #3: 4:00 AM (and zone watering times are now set to 10 minutes to get a total of 30 minutes of watering).  These intervals give the soil a chance to absorb water more evenly and deeply, and by watering this way, run-off is minimized. This method can also reduce brown spots, because the soaking method gives water a chance to move horizontally as well as vertically. TIP: Make sure you are in the right program before you start setting your timer – most timers provide for 3-4 programs (A,B,C..).  Using the soaking method can make changing your schedule very tedious.  Since you will need more water in the summer and less in the spring and fall, change the frequency from every 5 days in the spring and fall to every 3 days in the summer.  If you still need more water in the summer, turn up the seasonal adjustment from 100% to 125%, so that you are watering deeper, but not more frequently than every three days.

Many timers have a seasonal adjustment feature: Let’s say that in June, you are running each zone 3 times, for 10 minutes each, for a total of 30 minutes.  In the cool months like May and September, if you adjust the percentage to 50%, and each run time will be shortened by half (5 minutes) and so each zone will run for a total of 15 minutes. Likewise, in July and August, when your lawn needs more water, simply turn up the percentage to 150% and now you are watering for a total of 45 minutes.  Again in the fall, you can adjust the percentage back down again.  Using the seasonal adjustment feature is much easier than changing each run time time for each zone. Tip: if you leave your timer plugged in all year and just turn it to “off” in the winter, all of your programs will still be there in the spring.

Sprinkler Heads: Most traditional residential pop-up sprinklers have a fixed spray pattern and put water on too fast.  This provides another opportunity for the homeowner to save water.  Some sprinkler manufacturers like Hunter offer rotating pop-up sprinkler heads that apply water more uniformly and at slower rates than traditional pop-up spray heads. Additionally, these heads can reduce evaporation because they put the water on in bigger droplets than pop-ups.

Sprinkler head adjustment is another key to a water-efficient lawn.  In many locales, it is illegal to have water running over the sidewalk or other impermeable surfaces so making sure your sprinkler heads are adjusted properly will save water and reduce brown spots.  Many times, brown spots can be addressed and even eliminated with proper sprinkler head adjustment. The installation of a rain sensor provides another opportunity to save water because it shuts down your sprinkler system during and after a rain event.  Rain sensors can be purchased wherever sprinkler system components are sold and they are fairly easy to install. See local city information and rules for watering lawns and landscaping in Lafayette.