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May 20, 2013

Augusta Magazine / October 2011 / It’s Time To Winterize Your Lawn

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Proper lawn maintenance is as important in the fall as it is in spring and summer, even if it’s only a matter of knowing what not to do. To fertilize or not to fertilize? How much water should be applied if at all? How high should the grass be cut? This is important information to have in order for your lawn to winter well and be healthy for spring greenup.

Fertilization
Despite ads you may see on TV, feeding your lawn in the fall is not the thing to do. Such commercials are geared for parts of the country where cool season grasses are common, not for Augusta, where warm season grasses are typically grown.

The latest you should fertilize warm season grasses is September 15. After that, your grass starts to grow more slowly and it will not utilize the fertilizer well. Applying a high nitrogen fertilizer after mid-September will also make it less cold hardy and more susceptible to damage from turf diseases such as take-all patch and large patch.

Mowing Height
Another change for your fall maintenance list is to raise your mowing height.  The rule of thumb for Bermuda, zoysia and St. Augustine is to raise the height just a little (maybe one notch). This is particularly beneficial to Bermuda because raising the mowing height around the first of September will help keep its dark green color. And cutting your grass higher helps insulate the crown from possible cold injury. The exception to this rule is centipede, which is more likely to suffer winter damage if it’s cut higher. Also keep in mind that if you are planning to to overseed with annual or perennial winter rye for color, cutting the existing grass lower will make it easier to get the seed down to the soil.

Watering
Fall watering is perhaps the most  misunderstood maintenance regimen for homeowners. Many people continue to run their irrigation systems three days a week in the fall just as they do in the summer when common sense should dictate that a lawn doesn’t need as much water in the cooler, shorter fall days as it does in the long hot days of July and August. By failing to adjust the irrigation schedule you are not only wasting water and money, but also harming your lawn and other landscape plants. The only type of grass that needs  water on a regular basis during fall and winter is overseeded ryegrass or newly laid sod—if it has not rooted down well.

Though it is a rare occurence, if we experience two to three weeks without rain during fall, give your grass a light watering of around 15 to 20 minutes, which will be enough to wet the stolons. The goal is not the deep soaking you are trying to achieve in summer. By following these steps you will keep your lawn healthy during its dormant stage by decreasing the possibility of dead spots due to winterkill next spring. And a healthy lawn will green up faster in the spring.

Weed Control
The time of emergence of winter weeds varies, but on average, they start popping up during the last week of September through early October. An even better predictor is when night temperatures consistently drop between 55 and 60 degrees. This is also the time to apply pre-emergence herbicides.  

Keep in mind that pre-emergence herbicides only prevent annual not perennial weeds. Perennial weeds come back vegetatively while annual weeds come back strictly from seed. Therefore, if weeds appear in your lawn despite the fact you’ve applied pre-emergence, they are perennial weeds and will require multiple applications of post-emergence weed killers, spot applications of Roundup or else physical removal by hand.

Apply granular pre-emergence herbicides with a drop or rotary spreader. Divide the amount needed into two equal parts and apply in two directions at right angles to each other to insure a uniform distribution and help to prevent skips and excessive overlap.

Pre-emergence herbicides should only be applied on well-established lawns that have been in place for at least one year. If your yard has been recently sodded, pre-emergent may be applied if sod has been down for more than two months and is well rooted. Do not apply a pre-emergent if you are planning to overseed your lawn with ryegrass. Herbicides cannot distinguish between weed seed and ryegrass seed.  Be sure not to use a Weed-N-Feed product at this time of year, which contains fertilizer with pre-emergent, as late applications of fertilizer can damage your grass.

The herbicide needs water within a week of application. If it does not rain, water it into the soil. Any longer than that and it will begin to lose its effectiveness.

Pre-emergence herbicides are sold under a number of trade names with the most common being benefin (Balan, Crabgrass Preventer, etc.), pendimethalin (Halts, Lesco Pre-M Plus), and dithiopyr (Dimension, StaGreen Crab Ex, Crabgrass Preventer, Vigoro Crabgrass Preventer). All of these are virtually the same so you have a lot from which to choose.

Most if not all pre-emergence herbicides are 0-0-7, which means they contain 7 percent potassium, which helps prevent turf diseases and promote winter hardiness. Almost all Augusta lawns are deficient in potassium. If you have been using the same pre-emergent every year, change to a new one. Research shows that weeds can build up a resistance when the same herbicide is used over time. Always select a treatment that is labeled for your specific turfgrass, since they vary tolerance, and always read the label before applying.

If you have applied a late summer Weed-N-Feed in early August, you can wait about three months before you need to apply the pre-emergent. As for perennial weeds, it may be more effective to dig them up versus spraying. Hard to kill weeds like wild garlic (onion) take multiple applications of either Image or a combination 2,4-D product (Weed-B-Gon, Weedstop, Weed Killer for Southern Lawns) or Atrazine.
 
Take a Soil Sample
Fall is the best time of the year to take a soil sample, which is recommended every two to five years—every two to three years for sandy soils, as nutrients leach more quickly, and every three to five years with clay soils.

Knowing the pH and nutrient levels of your soil is important to insure a healthy lawn and critical in preventing disease. Proper nutrient levels will arm your grass with the ability to fight off diseases and make it more winter hardy. Soil tests can be done at any extension office for $8 per sample.

 

A healthy lawn is a source of pride and beauty. By following these basic management guidelines, your grass should stay healthy and happy through the fall and winter, and be ready to shine next spring, just in time for the Masters.