Summer is just beginning and already much of Virginia is under drought conditions.  Water is one of our most precious commodities, and even where plentiful, for most of us its cost dictates the necessity to be water stewards.  In this podcast, I’ll discuss some basic strategies in maximizing water-use efficiency in our lawns during the summer months.

What grass are you growing in your lawn?  If your region is suited to warm-season grasses (in Virginia this region is primarily from Richmond south into the Piedmont and then eastward into the Coastal Plain and Tidewater areas), then this type of weather pattern is one of the best reasons to convert cool-season lawns to improved warm-season grasses in the future.  Warm-season grasses are superior to cool-season turfgrasses in terms of water-use efficiency and established warm-season sods will typically survive extended drought with little concern for turf loss.  The primary characteristic that discourages people from using warm-season grasses in these areas of Virginia is its winter dormancy period when the grass is void of color for at least 4 months.  However, low water requirements are a very strong reason for us to utilize more of these grasses as water availability for our lawns and landscapes becomes even more limited. 

If you are growing cool-season grasses, then you need to make a choice regarding an irrigation strategy -- simply, do you or don’t you?!  If you irrigate, then your best management strategy is to water deeply and infrequently rather than applying 5-10 minute cycles every day.  Now, you can only apply as much water as your soil will accept in a given time period, but the concept is to thoroughly soak the top 4-6 inches of the soil in an irrigation event every 3-4 days.  This promotes the maintenance of as deep of a root system as possible.  And if you don’t have the ability, desire, or dollars to irrigate, then let Mother Nature take the lawn over.  Mature sods (even cool-season turfgrasses) will enter a state of dormancy under prolonged drought and its chance of surviving is far greater with this strategy than someone that attempts shallow, frequent irrigation events.   Note that I said “MATURE” sods.  If you have made a spring lawn establishment and you want to keep your turf alive, then you must commit to watering on a regular basis as often as possible to keep the soil moist and your new plants hydrated.  Entire stands of spring-seeded turfgrasses can be lost in one hot, dry afternoon without proper watering attention.  Both spring-seeded warm and cool-season grasses (but especially cool-season grasses) simply do not have enough root system developed to survive extended drought and heat periods.

The next point to consider in regular lawn maintenance that affects water use efficiency is mowing, particularly when it comes to cool-season grasses.  There are a couple of schools of thought regarding mowing height and water-use efficiency.  The largest group says that it is logical to raise the cutting height of grasses under moisture and heat stress (again, this best applies to cool-season grasses) in order to relieve the strain on the grasses.  Another group says that it is actually beneficial to continue maintaining these turfgrasses at their normal spring cutting heights because this reduces the amount of water lost by these plants due to having so much leaf surface area (For those of you interested in the science of turfgrasses, the entire process is called evapotranspiration.  Water is evaporating from both the soil and the leaf surface and is transpiring from the leaves through their openings called stomates.   The thought is, the more leaf area, the more stomates, and the more water loss.  This could all be very important to know if you ever end up on Jeapordy! someday soon!)  I suppose I fall more in the camp of the group that says basically mow it tall or do nothing at all under periods of moisture stress.  I believe this philosophy best fits most homeowners needs for their lawns.

Some other basic water management strategies to consider (especially if you have an in-ground irrigation system) involve maximizing its time of operation AND periodic inspection of the system to determine if it is functioning at maximum efficiency.  First, since these systems cost significant dollars, it is normal for folks to want to SEE their investment in operation!  There is something rather soothing and reassuring regarding the sight and repetitive sound of irrigation heads in action.  However, the most effective irrigation application timing on your lawn is well before most people would want to get up to see their system in operation!  If you have an automatic timer, use it to program your system to operate early in the morning prior to or just at sunrise.  Such early application timing ensures that distribution patterns are less likely to be affected by wind and even more importantly, this reduces the duration of leaf wetness and helps minimize fungal disease activity.  

Finally, inspect your system one to two times per summer season to ensure that heads are seated and angled properly to maximize irrigation distribution and amount.  You can use several small cans or plastic containers placed strategically in each of your irrigation zones to collect and measure water amounts for a known time period.  Any large variances in amount and/or distribution of the water indicate that you have a problem to address and usually it is quite easy to spot heads that are not properly functioning. 

These are the basic steps to success in lawn irrigation as another summer season is upon us.  Numerous written publications on summer lawn management are available through the Virginia Tech website and remember that you can always contact your local Virginia Cooperative Extension office for further information on successful lawn management strategies.