Winter Grass Arizona | Overseeding Bermuda With Ryegrass

While several warm-season types of grass are well-adapted to the dry heat of Arizona, there are none that also tolerate the state’s cooler winter temperatures (or vice-versa). So the best way to maintain a green lawn all year is by planting two different grass species.

Most savvy Arizonans plant a mixture of Bermuda and a ryegrass winter grass for year-round color. With the information below and some expert advice, you’ll have everything you need to know to do the same!

Preparing Winter Grass In Arizona, Texas

Getting the best results from this process requires more than just spreading a mix of grass seeds over the soil. Proper timing, preparation, and — of course — choice of winter grass are necessary to get the year-round lawn you crave.

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Choosing Annual Ryegrass Seed

There’s little debate over which grass seed is best suited to Arizona winters. Nearly all homeowners and landscapers turn to ryegrass in order to grow a green winter lawn.

Ryegrass is the preferred choice because it is affordable, easy to source, and germinates with little trouble. In Arizona, ryegrass flourishes during the exact part of the year that Bermuda grass typically goes dormant.

Annual Vs Perennial Ryegrass

There are two types of ryegrass available to choose from — annual and perennial. Annual ryegrass thrives in cooler temperatures but dies off when summer arrives. Perennial ryegrass can survive the entire year in milder climates. However, perennial ryegrass rarely fares well in areas as hot and dry as Arizona or Texas.

Most people choose annual ryegrass for winter overseeding because it lives just long enough for the Bermuda grass to take over come summertime. Annual ryegrass seed is also less expensive than perennial seeds.

Ryegrass Bermuda Seed Mix

Ryegrass and Bermuda grass play very well together on the Southwestern lawn. However, you’ll see little benefit from planting a mix of these two types of grass at the same time. Even if you plant perennial ryegrass, there’s a high likelihood that the grass will die off before wintertime. To get the results you want, you’ll want to establish Bermuda grass separately before overseeding with annual ryegrass in early fall.

Best Fertilizer For Ryegrass

Winter ryegrass requires maintenance just like any permanent lawn. After mowing your winter lawn at least twice, you can begin fertilizing.

Use a high-nitrogen fertilizer with a moderate amount of potassium. I recommend selecting an N-P-K ratio similar to 15-5-10 or 20-8-15. According to Clemson University, this fertilizer should be applied at a rate of one-half pound of nitrogen per 1,000 square feet.

Most winter ryegrass lawns will perform best when fertilized twice per winter. The first application should occur after mowing the lawn for a second time since overseeding. The second application can occur in 6 to 8 weeks as a winter fertilizer

How To Overseed Bermuda With Ryegrass

While overseeding with annual ryegrass is fairly simple, there are several steps I recommend following to achieve the best results possible. Cutting corners at this stage could dramatically impact the health and appearance of your winter lawn going forward.

How Much Seed Do I Need 

There is no cut-in-stone guideline for how much annual ryegrass seed you’ll need to cover an established lawn. According to the University of Arizona, overseeding with 10 to 15 pounds of ryegrass per 1,000 square feet produces optimal results. However, I have also received recommendations as low as 5 pounds per 1,000 square feet from equally trusted sources. You may need to experiment over the course of several years to determine what works best for your property. 

Preparing By Scalping And Dethatching

Before you distribute ryegrass seed over your lawn, it’s important to prepare the area by removing as much of the summer grass as possible. My preferred methods for this include scalping and dethatching.

Scalping is a simple process that involves lowering your mower blades almost to the ground. Cutting the grass at this height will remove the blades but leave the stem and root systems intact.

Thatch is a layer of dead grass tissue that can build up on the soil. If your lawn has a notable layer of thatch, you’ll want to remove it with a metal rake before overseeding. Failure to remove this material will prevent the new seed from reaching the soil.

Watering Schedule

Adequate moisture is the key to starting a lawn from seed, and winter overseeding is no exception. I recommend watering deeply several days before and immediately after planting the grass seed. Continue watering lightly 2 or 3 times per day depending on the weather. Your goal should be to keep the soil’s surface consistently moist as the seeds germinate.

Once the grass has sprouted, you can cut back to watering once per day. However, you should be saturating the soil more deeply each time you water to promote good root growth. 

After the grass is established and has been mowed a handful of times, switch to watering only when necessary.

How Long For Rye Grass To Germinate

One of the great things about using annual ryegrass for winter overseeding is that it germinates very quickly! With optimal care, you can expect to see growth within 7 to 10 days.

When To Overseed Bermuda Grass

Late September through early October is the best time to overseed with winter ryegrass in most parts of Arizona and the surrounding states. This time of year offers the ideal temperature for germination — neither too warm during the day nor too cold at night. While it’s possible to overseed later in the fall, you risk low temperatures that will impede germination and growth rates.

How long does it take winter grass to grow

Most ryegrass lawns are ready to be mowed within 21 days of planting. You can optimize growth by preparing the soil ahead of time, sticking to a regular watering schedule, and staying off of the grass as it germinates.

The growth rate is a big part of selecting a grass species for winter overseeding. Since you don’t want to wait months for the lawn to become established, a fast-growing variety like ryegrass is ideal. However, the downside is that you will need to mow frequently throughout winter to maintain your lawn’s height.

When Does Annual Ryegrass Die

Your annual ryegrass will begin to die off when the daytime temperatures reach or exceed 90°F. While many regions don’t reach such temperatures until well into summer, Arizona can experience them as early as late March.

I recommend scalping your annual ryegrass lawn when the average nighttime temperature is above 60°F. This will allow the summer Bermuda grass to fill in unimpeded.

Will Winter Rye Reseed Itself

In mild climates, annual ryegrass will go to seed in late spring. If the temperatures stay moderate and there is enough moisture, the grass may naturally resee and produce a new generation. But, at least in my experience, this rarely occurs in climates like Arizona.

Overall, I recommend cutting mature ryegrass in spring before seedheads emerge. Even if your ryegrass does manage to reach the seeding stage, you’ll likely need to oversee the lawn in the fall to fill in bare patches anyway.

When Can I Mow After Overseeding

As with any turf grass, it’s safe to mow winter ryegrass when it reaches a mowable height (generally about 3 inches). Continue mowing as needed to maintain the grass at the recommended height of 2 to 3 inches. Be careful not to cut more than one-third of the blades’ height per session. With adequate fertilizer and water, you can expect to mow every 7 to 14 days throughout winter.

FAQs Winter Grass Arizona