How much you have to water your Coastal Bend lawn and how often depends on how much help you get from Mother Nature and what kind of soil you are working with.
With clay soils it is best to water grass deeply once a week. The reason is simple - it allows the roots to grow deeper in search of water. The result is a stronger stand of turf grass.
If your yard is on the Live Oak Peninsula or Mustang Island you probably are working with sand, silty sand or sand with a clay layer underneath it. At times you will need to water more than once a week to keep grass going. A time tested rule is that it is time to water when you walk across grass and you leave a trail of footprints.
Planting groups of plants with similar water needs in the same area, known as hydrozoning, lets you use water more efficiently. Drip hoses are very effective in flower beds.
The Aransas/San Patricio Master Gardeners strongly recommend watering grass very early in the morning. That is when the wind is most likely to be calm and before higher temperatures and lower humidity will cause water to evaporate before it gets into the ground.
During cooler months of the fall and winter it is a good idea to check the soil moisture every week. If the soil is dry, water your grass, even if it does not appear to be actively growing. Consistent soil moisture is important to keep the roots hydrated so they can continue to grow and give you a better stand of grass in the spring. It is important not to over water. This can cause fungal root rot disease during cooler months. A local expert recommends watering landscaping and potted plants just before a cold front. Windy days suck moisture out of plants through rapid transpiration. This puts plants under stress.
ONE INCH PER WEEK - The typical yard needs about 1 inch of water per week in warmer weather. You can get a feel for how long it takes for your sprinklers to get that kind of coverage by placing standard size tuna cans in various spots in the yard and running the sprinkler for 30 minutes. The tuna cans are about 1 inch deep and give a fairly accurate reading of how much water is being delivered to a particular part of the lawn. Measure the water in each can and calculate the average depth of water in all the cans. Then use a spade to see how far down the moisture goes. If the soil is wet three inches down after 30 minutes of watering, you know you need to run the sprinkler for an hour to wet the soil to a depth of 6 inches.
For most suburban lawns a pair of 100 foot hoses will reach every corner of the lot. Try to use sprinklers that deliver large drops of water rather than a fine mist. More water will get to the ground. Your watering will be more efficient when the wind speed is below 10 mph.
Install a rain gauge and check it regularly. Subtract rainfall from the amount of water you apply to avoid over watering.
Water turf grass areas differently than shrub borders and flower beds. Some established shrubs and trees will need little irrigation except during extended dry periods.
Automatic sprinkler systems can be a tremendous convenience and allow you to manage irrigation more accurately than moving hoses and sprinklers. Experts suggest that it is generally better to have a professional irrigation company install sprinkler systems to avoid poor design. Ideally you should coordinate the landscape design itself, selection of plants and the irrigation system to maximize your water-saving scheme. The Master Gardeners suggest that a rain sensor be installed in the system so it will not run in the rain. Water utilities have found that people with sprinkler systems tend to water more than they would with water hoses. [MORE WATER SAVING TIPS]