Now is the time to overseed bermuda grass lawns with annual rye grass.
Bermuda grass, in both its common and hybrid forms, is not a cold weather turf. As soon as the winter chills come, it goes dormant and turns brown until the warm weather of spring returns. If you want your lawn to look green all year long, you will have to overseed it with rye grass. The keys for making a successful fall transition are: 1) plant at the correct time, 2) get good seed coverage, 3) hide the seed from the birds, and 4) keep the seed wet until it gets established.
Golf course superintendents throughout southern Arizona begin the annual transition from summer bermuda grass fairways and greens to winter rye and other cold tolerant turf varieties on or around Oct. 1 of each year. They choose to convert their summer bermuda grass turf to a winter hardy variety at that time because the warmer temperatures of early fall aid in seed germination and plant vigor while waiting until cooler temperatures prevail may cost them in a reduced stand and a slower growth habit. Both of those can seriously affect the quality of the playing surface. In residential lawns, we should take a leaf from their turf management book. If we want a thick vigorous stand of rye grass, early October is the right time to plant.
“Why not just let the lawn stay brown during the winter?” That is a choice, and many opt to do just that. It is less work and saves on water. One disadvantage of dormant turf is weeds. The soft, gentle rain that comes with our winter storms and cooler temperatures stimulate the germination and growth of winter weeds like Mediterranean grass, bur clover, creeping woodsorrel, shepherdspurse and others. After just one of these rains, brown, dormant lawns will soon be splotched with widely varying patches of green. This makes the lawn area look ragged, unkept and messy.
There are other ways, besides planting a cold weather grass, to maintain a well-kept, winter-dormant lawn. One way is to simply hand pull the winter weeds; but most of us soon find hand pulling is a never ending job that quickly gets old. Another way to keep winter weeds out of a dormant lawn is to apply a late fall treatment of a soil active herbicide like oryzalin. With good coverage and adequate movement of the chemical into the soil, a hassle free, dormant winter lawn can be maintained. We need to apply the weed killer late enough in the year that it will hang around long enough to carry us through the winter season, say three to four months, but early enough to avoid the first winter rain.
Overseeding the summer grass with a winter hardy variety easily solves pesky weed problems without having to pull or spray. The weeds still grow, but regular mowing will keep them at a uniform height with the grass and the green color of the lawn will mask and hide the green color of the weed. Another benefit of overseeding is the attractive winter lawn which nicely offsets the rest of the landscape.
If overseeding seems right for you, now is the time to start getting ready. These warm temperatures of early October are ideal for overseeding. If you wait until November, the cooler temperatures may slow the germination of the new seed and leave a skimpy, uneven lawn. The patches of bare ground scattered through the seeded area can be quite unsightly. Early October provides excellent temperatures for good germination and growth of the young seedling plants.
The best winter grass in my opinion is annual rye grass. Annual rye grass seed is fairly inexpensive and germinates well. The grass will stay green well into the spring, only dying out when the heat of June arrives.
Perennial rye grass is another possibility, but the real benefit to perennial rye is in milder climates where it persists from year to year. Because of the high summer temperatures in Pinal County, perennial rye grass will completely die out, except in shady spots. When this happens, we lose its primary benefit and one of the reasons that many plant it in the first place. In addition, perennial rye grass seed is also more expensive than annual rye grass seed. Okay, in all fairness, many feel that perennial for just a little more money gives a better look than the more coarse annual variety. In my cheap way of thinking though: save your money and plant annual rye grass.
When preparing to plant rye grass, it is important to remember that the heat-loving bermuda grass will most likely still be green at the first of October. In order to ensure proper seed contact with the soil, it will be necessary to thin out the growth of summer grass. This is most easily done by lowering the lawn mower blade gradually until you have scalped the lawn area close to ground level. It is important to remove all grass clippings. If a grass catcher is not available on the mower, it will be necessary to rake the area with a flexible leaf rake and remove the litter.
The next step is to apply rye grass seed over the relatively bare surface at the rate of 1 to 11⁄2 pounds of seed per 100 square feet. Be sure to distribute the seed evenly, either by hand or with a lawn seeder. It is also important to overlap the seeded areas to be sure of complete coverage. As you apply the seed, look around you. Chances are you will see that this most recent step has been watched with interest by every bird in the neighborhood.
These insatiable seed robbers can be foiled by covering the seeds with a thin layer of manure or other organic mulch. The mulch will help hide the seed from the birds and also help keep the seeds moist between irrigations. The mulch should be evenly distributed to a depth of about 1/4 inch over the entire area.
It is critical to keep the seed moist until it has germinated and has developed a root system capable of picking up sufficient water to meet the plants needs. Set the sprinkler to wet the entire lawn area. For best seed germination, apply light irrigations to the seeded area several times during the day, especially during the warmer parts of the day. The germinating seed must not be allowed to dry out during this stage or it will die. If water accumulates on the surface of the soil, it is okay to turn off the sprinkler temporarily, but do not forget to keep an eye on the seed and water again as necessary.
Water accumulating on the soil surface is bad because it may float out the rye seed and expose it to the air, birds or drying temperatures. Sometimes it will wash the seed into lower lying areas causing an uneven stand. When the water disappears from the soil surface, and the surface of the mulch begins to dry, be sure to start the sprinklers again. Scratch the surface to make sure water has penetrated the manure covering and has thoroughly wet the seed surface.
After all the seed has germinated and the area has a green cast, the frequency of irrigation can be cut back to once each day or once every other day depending upon the current temperatures. If wilting of the new grass seedlings becomes evident, be sure to water immediately!
The new lawn should be first mowed only when the entire area is approximately 2 to 3 inches tall. Use a sharp mower and remove the clippings during the first mowing. Set the mower to cut at one and one-half to two inches above ground level and repeat the mowing when the grass grows about 1 inch above the set level.
It generally takes about two weeks to get a good stand of rye grass in the fall, so patience and diligent care are essential.
The transition back to summer grass in the spring is much more simple even than the fall transition. Simply scalp back the annual rye grass with the mower in May or early June, whenever the nighttime temperatures reach 60 degrees F. on a regular basis and deep irrigate the lawn. Soon the bermuda grass will start growing again.
If you have questions, you can reach one of the master gardeners at the Cooperative Extension office, 820 E. Cottonwood Lane, Building C, in Casa Grande. The telephone is 520-836-5221, ext. 204.
Rick Gibson is an agricultural extension agent and the director of the Cooperative Extension in Pinal County. His email address is firstname.lastname@example.org.