Weekly Express-News Article

By Calvin R. Finch, PhD, SAWS Water Resources Director, and Horticulturist

Saturday, August 2, 2008

“Lawn Care in August”

It is six or seven weeks too early to fertilize the lawn for the fall, but there are other important tasks that can be completed in August.

If your lawn was plagued by winter weeds last year, now is the time to apply a pre-emergent herbicide to prevent germination of weeds such as bedstraw, henbit, thistle dandelions, annual bluegrass, wild carrot, and rescue grass.  Read the labels of the available pre-emergent herbicides and select the right one for the weeds that are your worst problem.  Quite often it is reasonable to apply one herbicide for grassy weeds and one for broad leaf weeds.

Follow the instructions closely, because to work well most pre-emergent herbicides must form an unbroken barrier of the active ingredient across the soil surface.  As long as the weather is warm the herbicide has a good chance to prevent weed germination.  Most years that means it can be applied up to mid September.

Now that we received some rain August may also be a good month to treat fire ants.  The baits such as Amdro seem to be the most effective long term control, but the ants must be actively foraging to find and carry the baits back to the mound.  The baits can be spread very thinly and still work well.  For mounds that show up by your patio, gardens or other areas of activity apply acephate fire ant killer directly to the mound.  The baits may take two weeks, but the acephate will kill in a few hours.  Ants that walk through it carry into the mounds on their feet.

August is still a good month to seed or sod a new lawn.  There is enough warm weather for Bermuda or buffalo grass germination and enough warm days left before cold weather arrives to have the sod root.

It is a very good investment to prepare your lawn site before planting.  Research conducted by Texas A&M and San Antonio Water System makes it clear that more than four inches of soil is required if you are going to have a lawn that can survive our periods of drought without breaking the budget for lawn irrigation.  Consider a total of six inches of soil.  Supplement your native soil with the addition of commercial landscape soil.  Landscape mixes include compost, sand and soil.  Incorporate the added soil into your native soil for best results.  Distinct layers of different types of soil are not as suitable for water efficiency and root growth.

Till in the added landscape soil and rake it smooth to remove rocks and lumps.  Apply two pounds of winterizer lawn fertilizer per 1000 square feet to the soil and apply enough irrigation water to penetrate through the entire six inches of soil mix.  In most cases that will be about an inch of water.

Spread the seed over the moist level seed bed with a drop or cyclone spreader at a rate of two to four pounds of Bermuda grass seed per 1000 square feet.  Check the buffalo grass seed package for rates on buffalo grass.

Water is the key to successful lawn seeding.  Irrigate every morning and every evening for the first week, once per week everyday in the second week, and every other day in the third week.  After three weeks the seed should be growing aggressively enough that the root system has penetrated the soil enough to take advantage of most of the soil reservoir.  The lawn watering just after seeding can be very shallow, because the soil reservoir is wet and the roots have not penetrated very deeply.  As the third week establishment period progresses, apply irrigation less frequently, but more deeply.  After the third week, in most cases once per week watering is sufficient.

Sod is treated in a similar manner.  Use the same watering regime.  Another key part of successful sod establishment is rolling the sod.  Your sod supplier or neighborhood rental vendor will rent you a roller that you fill with water.  Run it over the sod after it is laid.  The roller presses the sod into the prepared level soil bed to insure sod to soil contract.

My favorite grass for the shade is zoysia grass.  It makes a thick attractive lawn and zoysia can go dormant during a drought if water is short.  When it begins raining again, the grass greens up quickly.  Among the best zoysia varieties are El Toro and Jamur.  They are wide bladed.

In the sun the best choice seems to be Bermuda grass.  Bermuda can be seeded or applied as sod.  Bermuda has the ability to go dormant just like zoysia grass.  Consider common Sahara or Cheyenne Bermuda seed and 419 hybrid Bermuda sod.  Golf courses use Bermuda grass for the fairways and greens.

St. Augustine grass does not go dormant in a drought like zoysia or Bermuda, but there is one variety, Floratam, that performed as a well as zoysia grass in local drought tests.  Floratam St. Augustine has more shade tolerance than zoysia grass.

For more information on lawn grass varieties visit www.plantanswers.com.