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Fit in the OV: The benefits of winter over-seeding

Photo of Sam Orozco Parks Maintenance Superintendent

Overseeding, the practice of planting grass seed directly into existing turf lawns and sports facilities, is a widely used in Arizona and other locations that do not experience extremely cold temperatures.

Overseeding helps increase turf quality and aesthetics, attracting visitors from across the country who live in colder climates.

September 6, 2017

Prior to 1983, turf in Arizona was left dormant during the winter months, and in some golf courses, the turf was even painted with special turf paint to improve aesthetics.

After new ryegrass varieties were developed and tested, turf managers in Arizona began to use the overseeding process as a tool to attract visitors to their facilities. The overseeding process consists of transitioning from summer Bermuda grass to winter ryegrass. During overseeding, the warm season grass is forced into dormancy by lowering the height of cut, reducing water and in some cases spraying it with a retardant or growth regulator to suppress Bermuda growth and to give the ryegrass time to become established. Winter ryegrass comes in a variety of blends depending on the desired results. A good blend takes into consideration wear tolerance, water usage, heat tolerance, color and texture.

The overseeding of warm-season turf is known as transition. Transition is the period of time when a turf surface changes in the fall, from warm-season (Bermuda grass) to cool-season (ryegrass), and then again back to warm-season turf in the spring. The key to a good quality transition of ryegrass in the fall is to maximize the environment of ryegrass seedling germination. That is why the Bermuda grass is dried out and scalped down to ensure great seed/soil contact of the ryegrass. The scalping down of Bermuda grass gives the ryegrass the competitive advantage during this transition. The benefits of perennial ryegrass surfaces in the winter are many, including great turf surface, high traffic tolerance, high quality, lush appearance, reduced pollen from seed heads, and inviting places for year-round gatherings and events.

The Town of Oro Valley Parks and Recreation Department started the overseeding process in 2015, following the construction of the Naranja Park multi-sport fields in 2014. Since then, three Major League Soccer teams (the New York Red Bulls, Sporting Kansas City and Columbus Crew) have used our fields at Naranja Park. Now, more than 12 acres of turf at the Town’s various parks and recreation facilities are transitioned to winter ryegrass every year.

In the spring (late April/early May), as the soil temperatures warm up, the Bermuda grass comes out of winter dormancy and starts competing with the ryegrass. During this spring transition, horticultural practices help to give the Bermuda grass a competitive advantage, bringing it back full growth. During this time of transition, the fields appear to be in poor condition and are more susceptible to wear damage from excessive use. This is a normal part of the process. As temperatures increase, the ryegrass dies back and the Bermuda grass emerges as the dominant turf grass, providing once again, a beautiful, solid turf surface for all of Oro Valley’s residents and guests to enjoy.

By Sam Orozco, Parks and Recreation Parks Maintenance Superintendent - Explorer Newspaper, 9/6/17