“Help Me! My Grass is Dying!” What to Do When Overseeded Rye Dies in the Spring.
Words heard all over the Phoenix area as we transition from perennial rye back to Bermuda in the spring and summer. While there is no escaping the rye die-off completely, there is a lot we can do to ensure that the Bermudagrass underneath, in either sodded or seeded varieties, is ready to leap out of the ground when the time is right.
This method is for those who want Bermudagrass as their primary grass (April through October), either overseeded with rye or 100 percent Bermuda.
The Why
Bermudagrass doesn't die in the winter—it hibernates (just like a bear). It thrives when soil temperatures remain above 60 degrees and has 8 to 10 hours of direct sunlight. There are improved varieties, Tif-Grand, for instance, and others, that can tolerate less sunlight; this method works for those, as well. When we overseed, we are planting a competitor for nutrients and sunlight. The rye grass shades Bermudagrass stems growing above ground (stolons) and below ground (rhizomes), slowing soil warm up. This results in prolonging Bermudagrass dormancy. Our goal is to remove this canopy slowly so that we don't kill the rye, resulting in a brown lawn, while allowing vital sunlight through he canopy to warm the soil and “wake up” the sleeping Bermuda.
The How
The timing depends on your location (In Phoenix, I use March 1 as a starting date). There are three variables we control: mowing, irrigation and soil amendments/fertilizer.
Mowing: Each week—yes, you should be mowing at least every seven days—lower the mower blade one notch, or ¼-inch. By April 1, you should be at the lowest setting of your mower (¾- to 1-inch).
This accomplishes two of our goals: (1) Removing as much shade as possible to allow sunlight to hit both the dormant Bermuda and the soil, raising its temperature, and (2) We are minimizing the amount of rye so when it does burn out, there will be less of it to see. Leave your mower on the lowest setting until June 1, then raise it one notch per week until you are at your desired height for the summer (1- to 1 ¾-inch). It is vital to have very sharp blades on your mower—we want to cut it, not tear it. Torn grass tips turn brown...we want green! Sharpen your blades every eight hours of mowing. The mower doesn't work as hard and the appearance of the grass is improved.
Irrigation: Infrequent and deep is the key. Keep it simple:
Program A—example from Arizona:
Water days: Water once per week (spray heads twice per week). Set water day for the day after you mow to allow for a visual inspection of the turf when the soil is at its lowest depletion levels.
Start time: Splitting cycle into three allows time for soaking in: 2, 4 and 6 a.m.
Run time:
|
|
March (.9”ET) |
April (1.4”) |
May (1.6”) |
June (1.7”) |
|
12’ PRO=A or VAN** |
6 |
8 |
9 |
10 |
|
MP 1, 2 or 3000 |
45 |
70 |
80 |
85 |
|
PGJ-2.0, ½ circle |
30 |
45 |
52 |
55 |
Please note: These are times to be entered in a controller with three start times. 

**Spray heads should not run longer than 8 to 10 minutes due to extremely high precipitation rates, so you must change your water days to two times per week.
These are estimates only. Each zone's precipitation rate will vary. These assume catalog precipitation rates with square head spacing, with no distribution uniformity (DU), sun/shade or micro-climate modifiers and no rainfall or supplemental irrigation using 30 year turfgrass consumption values in Phoenix, Ariz., averaged from the University of Arizona.
The goal is to water to a 6-inch root depth, allowing a larger root zone, which in turn allows the plant to scavenge needed nutrients and water from a much larger volume of soil.
An easy way to determine water depth: about an hour after the last water cycle, use an 8-inch screwdriver (or better yet a soil probe) and push into the soil until it becomes difficult, mark the spot on the screwdriver and measure how far it went in—that tells you how deep you have watered.
Soil Amendments: For best results, get a soil test.
If you can’t do a test, try:
March:
I like a starter fertilizer low nitrogen here.
May:
June:
Core-aerate, and top dress with:
After aeration is an ideal time to put down amendments prescribed from a soil test, like humate, Mirimichi Carbonizpn, Gymsum or Kmag.
July:
August:
There you have it, a proven rye to Bermuda transition program, with a suggested summer fertilizer program thrown in. Enjoy your summer!
Stephen Wells is the branch manager at Ewing’s Queen Creek, Ariz., location. He can be reached at swells@ewingirrigation.com.
