Living in the valley of the sun has some great advantages. This includes having a lawn all year round. The two main types of turf used in southern Arizona include a perennial rye and Bermuda grass. The perennial rye is typically applied each fall to continue the green grass while the Bermuda rests for the winter. Summer grass also known as warm season grass is typically Bermuda grass. Bermuda grass thrives in the summer but goes dormant as nighttime temperatures dip consistently below 65 degrees. When nighttime low temperatures become consistent above 65 degrees then the Bermuda grass will essentially wake up and start growing, replacing the winter rye. Bermuda grass does not need to be planted each year as the perennial rye grass does, Bermuda grasses consist of rhizomes that live under ground and Stolens that grow along the surface that can continue to live by going dormant in the winter. There is a short time period in the spring when both the Rye grass and the Bermuda grass compete to survive. Because of this, the turf may not transition from green to green due to weather and temperature variances. It is normal to expect a 1-3 week where the turf may be brown until the Bermuda begins growing again.
There are a few things to prepare for this spring phenomenon, also known as summer transition that will help the Bermuda out of dormancy more quickly. The first tip is to begin to reduce mowing heights when soil temperatures begin to climb, allowing the sun to warm the soil, to encourage Bermuda growth. On a side note it is good to remember Bermuda does not like being cold or to be in shade. It needs full sun to be healthy and green throughout the summer. When there is heavy shade, Bermuda will struggle and will not look good.
Also, this is the time to start to reduce irrigation to the turf, but not too much. This begins to stress the Rye and let it know it’s time to exit the stage. It also helps reduce the chances of the Rye shading out the Bermuda and inhibiting early growth. There is an old philosophy of turning off the water completely, however newer research has shown that the Bermuda needs some water to begin growing and irrigation should remain on.
Dethatching is a good idea as well. Dethatching is a technique that rakes out the old thatch from previous seasons and gives the Bermuda more access to water and sunlight that would otherwise be blocked by old thatch. This should be performed in moderation and only when the thatch becomes thick.
Finally, aeration is a good practice that also allows water and sunlight to more easily reach the root zone and introduce oxygen and nutrients directly to the soil. This is done by removing soil cores from the soil.
Working to keep good soil conditions and practicing proper cultural practices will help ensure nice, healthy Bermuda throughout the summer. The primary causes of turf diseases can be linked to improper cultural practices such as overwatering. Bermuda is tough enough to handle brutal temperatures and conditions with proper sun and water conditions and is great choice for people wanting a summer lawn.
Bobbie Potts, MG, ACLP, SLM
ISA Certified Arborist WE#11574A