Do you like having a green lawn throughout the year? Do you like to mow, irrigate, and fertilize during the winter? Is it appropriate to overseed your lawn for the winter? These are just a few questions that you need to ask yourself before you overseed your turf. Warm season grasses such as Bermuda and zoysias go dormant during the winter months and can be over seeded with a cool season grass variety to maintain green color and adequate quality. This DOES NOT include St. Augustine grass which stays green-and-growing all South Texas "winter" long-unless we have a hard freeze below 20 degrees F. To gather some insight on this topic, I used some of the information from Drs. Jim McAfee and Roger Havlak, Texas A&M AgriLife Extension Service Turfgrass Specialists. The following is what they have to say about overseeding.

The best time to overseed the home lawn is mid to late October and early November, but more accurately after the first frost. Annual ryegrass is the fastest germinating variety and probably the cheapest. It looks very similar to perennial ryegrass with a dark green color and shiny leaves. Annual ryegrass grows quickly and requires frequent mowing (around 2 to 2.5 inch height) especially during late fall and early spring. Their water use rates are moderate and fertility requirements are low - maybe one to two pounds of nitrogen over the winter months. For a dense stand of rye grass, overseed at a rate of about 10-12 pounds of seed per thousand (33 feet by 33 feet) square feet. And keep the lawn irrigated for several weeks to ensure germination.

There are a couple of new annual ryegrasses from Lloyd Nelson at the Overton station. One is Excella and the other is Pantera. While these are annual types, they look and grow more like the perennial types. Texas A&M recommends the Pantera ( better color ) for homeowners anytime. The annual types will die out faster in the spring and therefore don't create as much a problem for the turfgrass growing in the lawn.

How to Overseed?

I would recommend aerifying the lawn 30 days prior to overseeding if possible. For some homeowners, this is not possible or too hard to do. Right before you overseed, scalp the lawn (NEVER scalp St. Augustine!) down as low as your mower will go. This will help get the seed down in contact with the soil, which is very important. Fertilize overseeded sites with a complete fertilizer such as 15-5-10 at 6 pounds 1,000 square feet. Apply fertilizer immediately after seeding so as not to "burn" the young seedlings. After seedlings emerge, light applications of nitrogen will help produce a dense, healthy stand of grass. As soon as the seed is planted, start watering. Water lightly a couple of times per day until the seed start to germinate and grow - this is not like when planting bermuda grass seed that you should water two or three times daily until the seed sprouts. If you water rye seed too much, it will rot.

Overseeding-Should You Do It?

Overseeding is defined as seeding onto an existing turf, usually with a temporary cool-season turfgrass (i.e. annual or perennial ryegrass), to provide green active grass growth during dormancy of the warm season turfgrass (i.e. bermudagrass). It is used extensively on sports fields and golf courses, and to some extent, on commercial sites and home lawns. Sports field managers and golf course superintendents overseed their turfgrasses primarily to offset the excessive traffic during winter play as well as to have a green, quality turf. But there are negative effects to overseeding. 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 overseeded grass at the expense of the re-growth of the warm season grass. Improved turf-type annual ryegrasses typically have a better spring transition than do the over seeded perennial ryegrasses. In years that favor continued persistence of the overseeding, there can be significant damage to the bermudagrass turf. Another big negative with overseeding is if the existing turfgrass should be "scalped down" to provide a seedbed to favor a quick fall transition to the overseeding turfgrass. This scalping, along with the fall competition from the cool season grass prevents the warm season turfgrass from being able to store the necessary carbohydrates in the fall months. This means the turfgrass is going into winter dormancy in a weaker condition, with less stored reserves to recover well the following spring. If you have a great deal of traffic during the winter period at your site, then overseeding may be appropriate.

What About Overseeding Damaged Turf?

Overseeding this fall might lead to warm-season turf with some very serious problems next year because of the summer we have had this year. A healthy warm season turf being over seeded is severely weakened as it is from the competition of the aggressive cool-season turfgrass being planted into it. Over seeded warm-season turfs are weak and sickly looking in the spring when they transition back to the dominant turf - imagine what you will likely have if you are overseeding an already thin turf this fall. Next year will be the easiest transition year you have ever had - know why? There won't be a transition for a lot of us because there won't be a warm season grass remaining! Instead of overseeding, you should raise the turf cutting height and make sure to apply a Winterizer fertilizer. Allow it to fully prepare for the upcoming winter by naturally hardening off through the day/night heating/cooling patterns of this time of year . You should also consider replacing large areas of damaged turf with Floratam St. Augustine (plantanswers.com/grass.htm) until late November. Turfgrass producers such as Milbergers are selling a 50-yard pallet of Floratam for $160. A 50-yard pallet covers 450 square feet with 150 pieces of sod which are 24 inches by 16 inches in size. A half-pallet or 25 yard pallet (225 square feet) of Floratam is available for $110. Milbergers will also take orders for smaller amounts to help people with less damage. But remember, ONLY Floratam should be used to replace the damaged St. Augustine caused by this summer's problems. See: plantanswers.com/brown_spots.htm. For those with small areas, take advantage of FLORATAM FRIDAY ST. AUGUSTINE GRASS at Milberger’s Nursery (milbergernursery.com/now-on-sale) where you can by pieces of Floratam every Friday -- Weather permitting. A 16 inch x 24 inch piece costs Only $1.29!

Expect a lot of winter weeds in an area with a thin turf cover. The thin turf that has received some rainfall during the last couple of weeks is sure to be invaded by a bumper crop of winter weeds. If you are not over-seeding, apply a fall pre-emergence herbicide AS SOON AS POSSIBLE. What is being used: these are the most common choices - prodiamine, pendimethalin, Balan plus oryzalin (Amaze) and dithiopyro (Dimension). All of these are excellent PRE materials, each with their own strengths and weaknesses.
Be very careful with late season cultivation events on warm season grasses after the summer we have had. The weaker your warm-season turf is, the more likely the damage this winter.

What About Instead of Overseeding Trying "Interseeding" of Thinning Turf?

The biggest problem encountered by homeowners, an especially pet owners, in this area is thinning turf in shady, high-traffic-by-pets areas usually planted with St. Augustine grass because of its shade tolerance. Throughout this column, it has been stated over and over NOT to overseed St. Augustine- but what about Interseeding of Pantera rye with St. Augustine. The term overseeding means to create a thick turf of rye on top of an established bermuda or zoysia turf. What I am proposing is that you folks with a sparse stand of St. Augustine in shady, pet-trampled areas, cut the overseeding rate by one-half (use 5 - 6 pounds per 1000) in an interseeding program. The benefits of interseeding are thicker turf and more organic matter added to the soil from the expanding rye root system. Cereal rye (Elbon) has been used for years in home gardens as the best nematode control and source of large quantities of "green manure" furnished by the decomposing rootsystem of the rye in the spring. See:
aggie-horticulture.tamu.edu/PLANTanswers/earthkind/ekgarden26.html If you want to try this use Pantera rye. Pantera rye is being sold in 50 pound bags for $90 (25 pound bags for $50) at local nurseries such as Milberger's Landscape Nursery. A 50-pound bag will cover 5000 square feet (one pound per 100 square feet) and is a lot cheaper and easier than resodding. HOWEVER, if you are trying to solve thinning turf in shady, high-traffic-by-pets areas you will be more satisfied sodding with Zoysia or St. Augustine grass because of its shade and traffic tolerance. If possible, aerify the area as recommended for the overseeding above. Fertilize periodically as well to maximize rye grass growth. You may have to mow more often than overseeding because the rye will not be growing densely and decreasing the growth rate because of competition.

Overseeding Bermuda Lawns With Bluebonnets

How would you like to grow weeds in your lawn this winter? Most folks recognize the reality of the situation -- they will have winter-weedy lawns whether they want them or not. To avoid winter-weedy lawns, pre-emergence turf herbicides must be applied before the winter weeds begin to germinate -- which is SOON.

Pre-emergence turf herbicides are not created equally. Each has its own desirable characteristics in weed species successfully controlled, safety to desirable turfgrasses and ornamentals, soil longevity, and cost-effectiveness. The most commonly available pre-emergence turf herbicides are listed above.

All pre-emergence turf herbicides are relatively safe on Bermuda grass at recommended rates used according to label instructions. Newly sprigged or sodded areas experience root damage and inhibition following pre-emergence turf herbicide applications. Thus, recommendations are to apply pre-emergence turf herbicides at one-half the recommended rate for newly seeded Bermuda grass.

If overseeding bermuda grass with annual rye grass or bluebonnets is considered, the areas to be over seeded SHOULD NOT be treated with pre-emergence turf herbicides within 60 to 110 days before planting in the fall, depending on the herbicide applied. Pre-emergence turf herbicides are not equal in their clearance for use around ornamentals and ground covers. Herbicide labels should be inspected for tolerance of ornamental species.

All pre-emergence turf herbicides should be watered into the root zone soil where weed seeds are located and to minimize loss from volatilization and photo-decomposition.

BUT, who wants to kill those winter weeds which give our lawns that "scattered green" look during the dead-look of winter? If folks could carefully choose the winter weed they grow, objections certainly would be minimized. If the winter weed stayed small and rather inconspicuous until February, surely no one would object. If the winter weed chosen would bloom next spring, that would even be better. If the winter weed was designated as the state flower of Texas, the weed infested lawn could be justified for the sake of patriotism. So everyone should overseed their bermuda grass lawns with the most beautiful winter weed that exists -- the bluebonnet.

Overseeding a bermuda grass lawn with bluebonnets is easy and certainly much more rewarding than letting non-patriotic weeds persist. You can pay for herbicide to control weeds or buy seed with which to grow a weed (bluebonnet) that can out-grow and out-bloom most other winter weeds. This bluebonnet weed can also provide an additional benefit other than beautiful spring bloom -- it has the ability to take nitrogen out of the air and put it into soil for use by lawn grasses in the summer.

To accomplish this patriotic weed planting of the lawn, you must first have a bermuda grass or zoysia lawn growing in an area which receives 8-10 hours of direct sun daily -- St. Augustine lawns DO NOT qualify. St. Augustine lawns do not go dormant soon enough in the fall and they begin to regrow too soon in the spring. Generally bermuda and zoysia lawns begin dormancy in October and do not begin green-up in the spring until late April or after the full bloom cycle of bluebonnets is completed. Both the green-up of bermuda and the bloom cycle of bluebonnets are moisture and temperature controlled so the two should never significantly overlap. Also, good-growing bermuda lawns can only exist in sunny locations and bluebonnets only thrive and bloom profusely in sunny locations.

The overseeding procedure involves:

(1) Aerate the bermuda turf area no later than November 10 with a soil plug-removing (rather than poking type) aerator (available at rental stores) This is a good cultural practice for compacted bermuda lawns anyway.

(2) Immediately after plugging the lawn area, sow ONLY scarified bluebonnet seed (bluebonnet colors such as blue and Alamo Fire ('Texas Maroon') at the rate of one pound (17,000 seed) per 1000 square feet and rake the area with a lawn broom to evenly distribute the seed and to make sure some seed fall into the holes punched by the plugging machine. Not all seed has to be in the plugged holes since the turf grass surface will be "roughed" enough from the aerifying process to provide enough soil-seed contact to enable seed germination. Wildseed Farms at Fredericksburg (www.wildseedfarms.com) is a major source of the scarified bluebonnet seed.

(3) After sowing the scarified seed (scarified seed is necessary to insure immediate and rapid germination and establishment before cold temperatures occur because of the late seeding date), thoroughly water the area. Watering during the winter SHOULD ONLY OCCUR if monthly rainfall is not received. Fall fertilization can be applied as usual.

(4) Competing grassy winter weeds can be controlled by spot-treating the grassy areas with fusilade-like herbicides such as Grass-B-Gon (NOT WEED-BE-GON or BRUSH-B-GON!!), Ornamec, Hi-Yield Grass Killer, Fertilome Over-the-Top, Sethoxydim, and Fwazifop . This herbicide can be sprayed onto bluebonnets and will kill surrounding grass AND NOT DAMAGE THE BLUEBONNETS which are not grass. If, however, other broadleaf bluebonnet-like weeds such as henbit or clover begin to over-shadow the state flower, you may have to intervene with a bit of weed pulling exercise -- there is no herbicide which will kill other broadleaf weeds and not kill broad-leaved bluebonnets.

(5)AND LAST BUT CERTAINLY NOT LEAST, before you even plant the first bluebonnet seed with which to create a beautiful, patriotic weedy lawn, be reconciled to the fact that YOU MUST REMOVE (shred and mow) the large bluebonnet plants IMMEDIATELY after they bloom next April or you can and will damage the bermuda grass turf. You MUST realize that this is a new and sophisticated technique of beautifying a dull, brown bermuda grass lawn -- NOT a technique of insuring a bluebonnet-weedy, lawn-pasture for eternity by allowing plants to remain dying and ugly until seed are mature in June. Overseeding will occur every fall so that designs and colors can be altered and bermuda grass turf will not be damaged (summer green-up of grass will be delayed). This will also alleviate the necessity of neighborhood partitions to force you to clean up your "weed" infested lawn!

For more information about overseeding lawns with perennial rye (Pantera or XLT),
search our database of previously answered questions for overseeding.