Correct watering is crucial for promoting deep root growth and general good health of your lawn; some other benefits that come from good watering practices are the reduction of pests and the decreased chance of thatch and grass diseases.
You can, of course, water in any season of the year but the main thing here is to water only when the lawn needs it. Over watering and shallow watering can cause many problems that will affect the entire well-being of your lawn, some of these problems include a short and weak root system, increased thatch and less resistance to weather extremes and wear. You will know that your lawn needs to be watered when it shows signs of drought stress; the most visible evidence of drought stress are a bluish-green color to the lawn and when the grass is walked on the footprints remain or disappear slowly. These are good signs that it is time to water.
If you are still doubtful you can buy a soil probe or simply use a thin metal rod approx 3 feet in length; a long screw driver will also do the job. Gently insert the rod into the ground and it will be stopped by the dry soil. As a general rule if the probe stops within 4 inches then it is time to water and if it reaches deeper then 8 inches you have over watered. Many factors can affect what time of the day and how much your water; some of these are the grass type, humidity, rain, wind, temperature, soil type and slope. This makes it hard to give an exact solution for each lawn; however some general rules will help you to get it right. There is an optimum time that all lawns should be watered, and that is between 5 and 7 am. This is because it is cooler, causing less evaporation and winds are less likely to blow your lawn dry.
If you have an automated system, night time watering is also an efficient option, as the temperature and humidity are also favorable, however, it is important to time the finish of the watering cycle just after sunrise. If none of these alternatives is possible for you and you must water in the afternoon make sure that you finish watering 30 minutes to 1 hour before sunset, as water droplets left on leaves can easily lead to disease. Watering at this time will not harm your grass, although it is the less efficient.
Water deeply but infrequently, this means wetting your soil all the way down just to blow the bottom of the grasses root system, which is usually between 6 to 8 inches. You can test this with a soil probe or by digging up a small patch of lawn. In sandy soils ½ inch of water is needed and will typically soak down to the desired depth in 30 minutes, loam soils need an inch of water, and this will take 2 hours to absorb whereas clay soils require approximately 1 inch to 1and1/2 inches of water and may take up to 5 hours for absorption to the root level.
If you are using a hose (hose reels or expandable hoses are a really good choice) or a sprinkler you can measure the amount of water used by placing four equally sized cups between the start and the finish of the waters stream. Take note of how much time it needs to fill the cups to the desired amount for your lawn e.g. 20 minutes for ½ an inch of water for sand based soil. This will more accurately help you to identify how long you need to water and if your sprinkler is dispersing water evenly. After fertilizing, your lawn grows faster and will require more water, monitor the soil moisture more closely after these periods and try to keep the ground damp. Try to fertilize sensibly and only when needed as this will reduce the amount of water required. Shady areas of your lawn need less water than sunny areas due to the difference in evaporation and it is a good idea to monitor and water them accordingly. This may involve doing soil probe tests on different parts of your lawn.
If you have a large slope on your lawn, runoff can cause problems, particularly in the top of the slope. Take your time with slopes and water them slowly to allow the water to sink in, this is especially important in clay soils that absorb water at a slower rate. There are many forms of irrigation that can be used to save you time and effort and cater for any budget; they range from the good old garden sprinkler to the high-end underground irrigation systems and everything in between. There are also new devices, such as moisture sensor and rainout devices that can help to automate your system so that your lawn receives the optimal amount of water. There are specific sprinklers that work best in oddly shaped lawns and restricted areas to help avoid wasting water.
When considering your irrigation options, it is wise to take a layout of your lawn as well as your soil and grass type to an irrigation specialist to ensure you get the right system for your needs. If using a sprinkler don’t forget to use a cup for measuring the amount of water used and move the sprinkler to ensure you get an even covering. Remember that no matter what kind of watering system you use, whether it is a garden hose or a high-tech irrigation system, you should only apply enough water to wet down to just below the root system. It is also better for your water bill, the environment, and your lawn if you only water at the first signs of draught stress.
Another great way to save on your bills is just to mow your lawn at its tallest recommended height, which allows the grass to keep more moisture.