Kicking the Habit

Many people in the valley, both professionals and homeowners alike, wrongfully believe that a cool season grass such as tall fescue needs constant watering to survive our harsh desert summers. I do not subscribe to the same philosophy and over the next few entries hope to prove to you how it can be done with a little preparation and conditioning.

Most landscape professional use a diet heavy on nitrogen and water to maintain a lush, green lawn. This is the easiest and quickest way to provide their customers with what appears to be a healthy lawn through most of the seasons. Unfortunately, after a few years on this meal plan, the lawn begins to become infested with weeds and often experiences disease and death. At this point, the lawn care provider can up-sell the customer to include a herbicide program to keep the weeds in check; seed or sod to replace the dead turf; and of course more fertilizer to help weak grass recover during the hot months of summer. It also makes the grass dependent upon these inputs and it will show signs of stress when one or the other is not applied frequently enough.

A truly healthy lawn begins at the roots. Roots will search for water, driving deeper into the soil and branching widely, when it is not excessively available at the surface. When water is constantly present, ignoring for a moment the anaerobic ramifications that can occur, which is a topic for another discussion, the roots find no advantage in penetrating the soil and the majority of its mass is located close to the surface. After that consistent water, if the water were to disappear for a day or two, the roots can not handle such a condition because they have not built the support system and the plant goes into stress. Conversely, where the plant has already been stressed and the roots are deep within the surrounding soil, after a day or two without watering, the plant can more readily access water that is present in the lower profile.

Fall is a perfect time to begin transitioning your lawn from a thirsty water abuser, to a drought tolerant survivor. As the temperatures begin cooling down, evaportranspiration rates allow you to start slowly weening your lawn off of its crutch. Below are the basic principles you want to follow when setting your irrigation controller.

1. Deep, infrequent watering it paramount to developing and maintaining a healthy root system.  Allowing the soil to dry out between watering cycles forces the roots to drive deeper into the soil in search of water.
2. Cycle/Soak is the process of allowing one cycle of water to soak into the ground before the next round is applied. This reduces wasteful runoff and helps drives salt buildup through the soil profile. Watering cycles should be spaced at least one hour apart. More if you have heavy soils that do not drain well, less if your soil drains rapidly.
3. Watering early in the morning reduces water loss due to environmental conditions. Watering in the evening promotes disease and pests. 
4. Always set your drip irrigation and lawn irrigation on separate programs in your clock (A vs B).  Most irrigation clocks allow for this option.  This allows you flexibility in how you water two distinctly different zones. 
5. Drip irrigation should run in a similar fashion, where the first run soaks the rootzone, is allowed to settle into the soil, then the second round is applied, pushing the water even deeper into the soil.
6. General guideline is 3-5 minute runs on turf (every lawn is different and should be adjusted based on your observations and historical knowledge) and 30-45 minutes for drip (again, there are a wide variety of emitters out there.  Know your flow before setting your time.)

A properly programmed and operating irrigation system will allow you to condition your lawn to handle the harsh summer weather of Southern Nevada.

JM