Your lawn is receiving timely Lawn Care Applications….
You do a great job of mowing frequently…
Shouldn’t that guarantee you have a great lawn?
Not necessarily.
There is one more thing that has an impact on the quality of your lawn, and it’s a big one. … it is the one that is completely outside your control…Environmental Conditions.
What are environmental conditions?
Air & Soil Temperature
Rainfall & Soil Moisture
Sunshine & Wind
(Oh, don’t you wish you could control the environment!)
Let’s have a visit about how these items have impacted your lawn so far this year, what we can expect for the summer, and how we should respond.
Air & Soil Temperature
Bermuda lawns felt the impact of record cold temperatures in February. Thin or weak areas took the hardest hits. We even noticed some Bermuda in partially shaded areas froze out. Also, Bermuda lawns that were under stress last season due to unhealthy soil conditions, insect damage, drought stress, etc., started the growing season with patchy areas of dead turf.
The driving factor to warm-season turf greening up and actively growing lawns is soil temperature. All spring, soil temperatures lagged. Bermuda lawns were slow to fill in completely, especially on the north sides of structures and in partial shade areas where soil temperatures were slow to warm.
The extreme cold of February revealed many struggling Bermuda lawns as they came out of dormancy.
A few key soil temperature points:
Soil temperature of 55 degrees is when fescue starts to absorb nutrients, regains a rich green color, and begins prolific growth. Most years in central Oklahoma, March is the month to start fertilizing Fescue. Fertilizer applied to fescue before soil temperatures reach 55 degrees is mostly a waste.
This year soil temperatures reached 55 degrees for three consecutive days March 11-13. From that point through the end of April, soil temperatures were on a roller coaster. We would have a few days in the upper 50’s to lower 60’s, then a few days in the low 50’s.
Soil temperature of 65 degrees is when warm-season grasses (Bermuda and zoysia) begin to green up. Then once soil temperatures consistently reach 70 degrees they will begin actively growing. In a typical spring, we expect Bermuda lawns to green up gradually during April and be active growing by early May.
This year we experienced a cooler than normal April. Soil temperatures didn’t reach 65 degrees for the first time until May 9th. A few days later they were back into the low 60’s. Our first day this year for 70-degree soil temperatures was May 23rd. We were encouraged when they stayed there for nearly a week, only to become discouraged when they fell back to the low 60’s at the end of May. Now nearly a month behind, over the last 7 days we have finally seen soil temperatures consistent enough for Bermuda lawns to become fully active. Bermuda lawns all over the metro area finally rejoicing by putting on their summer colors. All the while, fescue lawns have spent the last three months putting on a show; the result of the cooler than normal start to the season.
Now that we are getting consistently warm days, start cutting fescue at 3” to 3.5”.
Bermuda lawns are responding to the 70 plus degree soil temperatures.
Other environmental factors that will impact spring green-up: Shady areas and turf on the north side of homes will come out of dormancy slower because the soil temperature will lag. Low moisture levels during the transition period will slow green-up. Turf grass that must compete with weeds for nutrients and moisture will also be slower. And compacted soil will slow the process by restricting air, nutrient, and water movement to the roots.
It’s the beginning of summer and there is one important thing you can do to help your lawn as temperatures climb - adjust mowing height. As Bermuda lawns start growing faster, gradually raise your mower. The goal is to be cutting at the maximum height for Bermuda, 2” to 2.5”, by the middle of July. Fescue lawns should be kept at 3” to 3.5” now through the end of the summer. Mowing at the maximum height for your turf type during the hot summer months provides a canopy that cools the soil and promotes a deep root system.
Rainfall & Soil Moisture
In the past 30 days, rainfall has been good. The metro area totals range from 4” to 7” since the first week of May.
Soil moisture readings are high, but with the arrival of 90 degree days, you can expect soil moisture to diminish quickly.
When it comes to watering, the first step is monitoring rainfall and supplementing water when needed.
Lawns need 1” to 1.5” of water per week during the summer months to stay green and active.
Fescue, when watered with deep soakings every other day, will stand up to 90+ temperatures.
Deep soakings are always best. Short, shallow watering is detrimental to your lawn and landscape in the heat. The healthiest lawns are watered to the point of runoff and then allowed to dry for a day. Daily watering, except for newly planted lawns, is not beneficial, even in 90+ degree heat.
Only water in the early morning. This is typically the least windy time of day and always the time of the least evaporation. Avoid watering in the evening. Wet grass, especially wet fescue, is prone to disease when it stays wet for more than 5 hours at a time and nighttime temperatures are in the 70s.
How long should you water? Every irrigation system is different – different head types, different size nozzles, different head spacing, different areas, etc. The best way to know how long you should water is to place a few cans around your lawn in a random pattern. Run your sprinklers through a cycle and measure the amount of water in the cans. If the sprinklers ran for 15 minutes and you had .25” of water, you need 60 to 90 minutes per week. Next, determine how long you can run your irrigation before you there is excessive runoff. This will tell you how many times per week you need to water. If you can get away with watering every 4th day, you will have a healthier, stronger landscape. Unfortunately, with our tight soils, watering every other day on the required ODD/EVEN system during the hottest times is needed to get the correct amount of water on the lawn without excessive runoff.
If you don’t have the time to audit the amount of water your system puts out, start with these settings, monitor, and adjust: Fixed spray pattern heads with 10-15’ spacings – 15 mins per time. Larger rotor-type heads on 10-30’ spacings – 40 mins per time.
Set your controller to water with back-to-back run times to reduce the amount of runoff. The moist soil absorbs more water than dry soil. Split the amount of time each zone runs in half and set your controller to come on twice on your water days. Example: Set controller to come on at 4:00 AM and 5:00 AM. When the first cycle is complete, the controller will start the second cycle.
I started the practice of setting irrigation controller to run back-to-back run times a few years ago, on slopes, and gradually have incorporated the concept to all lawns.
It really makes a difference in water efficiency.
Aeration improves moisture absorption. You can’t beat aeration for improving your soil structure and a benefit of improved soil structure is better to water absorption. Lawns that are aerated every year (or at least every other year) do not experience as much runoff.
Watch for uneven water patterns. If you notice areas where the lawn is fading, check your system for a broken head, clogged nozzle, or a head that is out of adjustment.
Even if you don’t have an irrigation system, the concepts of good watering apply. There are several brands of inexpensive hose-type timers that make it easy for you to control the timing and frequency.
Too much water can be a problem. Fescue’s biggest problem is brown patch. Brown patch will develop when nighttime temperatures are in the 70’s and the leaf blades stay wet for 5 hours or more at a time. Don’t create your own microclimate that promotes disease by overwatering, watering too often, or watering at night.
If you notice areas where your lawn is fading start with an irrigation check to make sure heads are functioning correctly.
Sunshine & Wind
Turfgrass moisture loss is much higher on windy, sunny days. This is a fact we often overlook and fail to adjust for.
Turfgrass leaf blades contain a lot of moisture. On windy days, the amount of moisture loss from the plant is substantial. After a windy day or two, be on the watch for an increase in drought stress. It is common to see dry areas along the south and west sides of lawns.
An often overlooked…especially important…environmental condition: Low wind areas of your lawn, areas with thicker plant materials, privacy fences, and structures are more prone to diseases due to low air circulation. Be aware of these areas and make sure you are not keeping them too moist.
A good source for monitoring all weather data is mesonet.org.
The Oklahoma Mesonet is a world-class network of environmental monitoring stations. The network was designed and implemented by scientists at the University of Oklahoma (OU) and at Oklahoma State University (OSU).
The Oklahoma Mesonet was commissioned on January 1, 1994 and consists of 120 automated stations covering Oklahoma. There is at least one Mesonet station in each of Oklahoma's 77 counties.
At each site, the environment is measured by a set of instruments located on or near a 10-meter-tall tower. The measurements are packaged into "observations" every 5 minutes, then the observations are transmitted to a central facility every 5 minutes, 24 hours per day year-round.
The Oklahoma Climatological Survey (OCS) at OU receives the observations, verifies the quality of the data and provides the data to Mesonet customers. It only takes 5 to 10 minutes from the time the measurements are acquired until they become available to the public.
We all wish we could control the environment and create the perfect conditions for our lawns year after year. Believe me, I have tried, and it isn’t possible.
So, what do we do? When it comes to the impact of environmental conditions on your lawn, you need to be aware, monitor, respond in the best way possible, and learn to be more patient when conditions just are not best for your lawn.
Our goal, no matter the current conditions, is to help you have the best lawn possible.
Lorne Hall
Hall | Stewart Lawn + Landscape
(405)367-3873