Gardens

Go Green With Your Winter Lawn
In you're willing to take the time and effort, you can have a green lawn all year long.

by Sid Mullis

If the prospect of a dormant, brown lawn encourages the winter-time blues and dampens your gardener’s spirit, you may want to consider overseeding your lawn this fall with ryegrass. For years, sports field managers and golf course superintendents have overseeded their Bermuda turfgrasses to offset excessive traffic during winter play as well as to have a green, quality turf even during the grayest days of winter. And many businesses have followed suit to enhance the appeal of their commercial landscapes.

The Basics:
For successful overseeding, you will need to do the following: Choose the proper seed, prepare for and time the overseeding, maintain the overseeded grass and manage the spring transition back to the warm season grass. You also need to maintain a healthy warm-season turf all year. It’s particularly important to keep the soil fertile, relieve soil compaction and prevent excessive thatch.

Before you decide to overseed, there are several things to consider. First you must be willing to mow the grass on a regular basis from late fall through winter. You must also consider the amount of water needed to keep the ryegrass healthy. Lawns require a lot of water when the seed is first put out and until it is well established.

Watering has become more of a cost factor as the price of municipal water has climbed over the past several years. Also realize that you will have a higher sewer rate for an entire year because this rate is based on water usage in December, January and February in Richmond and Columbia counties. If you overseed every year, consider installing a separate meter where no sewer charges apply. This would be a large upfront expense, but would pay for itself after several years.

Another factor is the permanent warm-season grass you have for your lawn. According to John Grantham, a former golf course superintendent who was in the business for 30 years and now owns Help Landscaping, Bermuda grass is the only grass he would recommend overseeding. “I personally wouldn’t overseed St. Augustine, zoysia or centipede because they are grasses you cut a lot higher and if you cut them low in the fall, you are going to hurt the roots because a lot of the roots and rhizomes grow near the surface of the ground,” he says.

Scalping warm season grasses prevents them from being able to store the necessary carbohydrates in the fall months. This will cause the turfgrass to enter winter dormancy in a weaker condition with less stored reserves to recover well in the spring.

No matter which grass you overseed, you should only do so on a healthy permanent lawn. Overseeding a weakened turf will only cause more problems during spring greenup. Competition between the cool and warm season grasses can be great, especially in the early spring when the warm season turf is trying to re-grow after winter dormancy, often referred to as spring transition. If the spring is cool and wet it will favor the persistence of the ryegrass at the expense of the re-growth of the warm season grass.

Choosing Seed
The seed you choose is the grass with the characteristics best suited to your particular needs. Annual ryegrass has almost completely fallen by the wayside in the past several years and has been replaced by perennial ryegrass because of its improved appearance (much darker green color), quality, stress and pest tolerance, and manageability.

Don’t be fooled by the name “perennial” ryegrass. It is not a true perennial this far south, but it can come back the next year in patches. So if you don’t plan on overseeding every year, it could potentially become a nuisance. In most cases the patches won’t persist for more than a couple of years.

Use high quality certified (blue tag) seed that is free of annual bluegrass to maintain weed-free turf. Use seed treated with fungicides since fungus thrives during unusually warm fall and winter temperatures.

When to seed

The ideal time to overseed lawns in the Augusta area is about two to four weeks before the average annual first frost, which is from about November 10-20. Therefore the middle of October through the first week of November is the prime time. Seeding any earlier in October and there is still the potential for 80-degree days, and ryegrass prefers daytime temperatures in the 60- to 70-degree range to germinate.

It is important to prepare the permanent turfgrass for winter. As the temperatures drop in the fall, water demands decrease. Take care not to overwater so that your grass will slow down its growth. To also minimize growth of your turf grass, don’t fertilize for two to four weeks prior to overseeding.

Soil-to-Seed Contact

The best way to make overseeding successful is to get good soil-to-seed contact. According to Grantham, when it comes to overseeding Bermuda, “Cut the grass as low as you can (scalp it), catch all the clippings and get all the thatch out of there to make a good seed bed. You want to have the seed as close to the ground as possible,” he says.

You can de-thatch the lawn by using a verticutting machine, available at tool rental stores. If your lawn is really small, you can rake most of it out, but be forewarned that this can be demanding work.

Overseeding a heavily thatched lawn tends to result in irregular patches of overseeded grass. Seeds that germinate in thatch or above the soil surface are more susceptible to cold damage and are also likely to dry out and die.

If you decide to overseed St. Augustine, zoysia or centipede, the preparation is a little different. With those grasses lower the mower one notch so it won’t be a severe scalping. You can use a machine to de-thatch zoysia, but it’s not recommended for St. Augustine or centipede because it will be more challenging to get seed-to-soil contact.

Overseeding rates for lawns normally range between five and 15 pounds per 1,000 square feet. Use the higher rate for a thicker stand. Grantham says you can go as high as 35 pounds per 1,000 square feet on Bermuda. Sow half the seed in one direction and the other half in a direction perpendicular to the first. This method will help establish a uniform stand of turf. Even though you are ideally putting out fungicide treated seed, Grantham says you might also apply a systemic fungicide to help prevent disease.

After Seed

After seeding, rake the ground with a broom or drag the ground with something to ensure the seed makes contact with the soil. In thicker stands of turf where it is not scalped or raked, topdressing with a thin layer of topsoil will give the seed a better chance of germinating.

Water the lawn lightly two or three times daily until the seed germinates. Do not overwater, as this will wash away seed and may cause puddling, which encourages disease. After the seeds germinate, gradually cut back on the frequency and increase the time of watering until you can establish a normal irrigation program. Water only as necessary and not on a regular schedule. Pythium blight disease can be a problem in overwatered, overfertilized ryegrass, especially during periods of unseasonably warm, humid weather.

Begin mowing when the seedlings are 30 percent higher than you want. Use a mower with a sharp blade and mow when the grass is dry to reduce seedling injury. Wait to fertilize until after the seedlings emerge, usually about three weeks after seeding. Earlier fertilizing can encourage warm season turf competition. Fertilize at about one pound of nitrogen per 1,000 square feet per month. This would equate to 6.25 pounds for a 16-4-8 or 10 pounds of a 10-10-10. Cricket manure is also a great fertilizer to use.

Keep in mind that if you decide to overseed your lawn, the areas in question should not be treated with pre-emergence herbicides within 60 to 110 days before planting in the fall, depending on the herbicide applied and how much it has rained. The herbicide cannot distinguish between weed seed and ryegrass seed.

Spring Transition

When spring comes, it will be time to make the transition back to your permanent turfgrass. A good transition requires knowing and making use of normal climatic conditions. Most warm season grasses resume growth when soil temperature approaches 60 degrees, usually during March. To discourage the ryegrass, stop fertilizer in March and don’t let the permanent grass suffer from lack of water at this time.

Maintaining a mowing height that prevents the ryegrass from shading out the warm season grass is critical to a smooth transition. Lowering the mowing height as the soil warms will stress the ryegrass and aid in warming the soil. Ryegrass normally dies out in late spring, but if cool weather persists, it can hang on longer than normal. When temperatures are high enough, apply a soluble nitrogen fertilizer to encourage warm season growth and cool season decline.

To keep the ryegrass looking its best through Masters week, delay all of these transitional maintenance practices until after Masters is over. Naturally this will further delay the greenup and growing of your permanent grass.
The downside of overseeding has been mentioned as it relates to the permanent grass, but to many people who want a year-round green lawn, it is still worth it. Are there any benefits to the permanent grass? There can be. There are a couple of good things that come from ryegrass. One is you are adding organic matter (green manure) back into the soil when it dies and your lawn benefits from the expanding root systems left by the ryegrass. Think of it as mini way of aerating.

Having that beautiful green lawn year round can be a lot of work, but to many Augustans it is well worth the effort, especially when Masters rolls around in April and the focus is on green. v

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