Watering Efficiently

Water Sprinkler System on in the grassIn Needham, the volume of water used on a summer day can be more than double the volume used on an average winter day. Lawn watering is almost exclusively the cause of this increase in water demand. Given that the summer is the time the Charles River is naturally the most stressed, becoming more efficient in our lawn watering practices can provide a significant benefit to the health of the river. In general, turf grasses need about 3/4 inch to 1 inch of water per week to maintain green color and active growth. The following tips will help you maintain a healthy lawn and garden while conserving water!

  • Water as infrequently as possible.
    Thoroughly water when you do water so moisture soaks down to the roots. Exceptions to this general rule would be for newly seeded lawns where the surface needs to stay moist, newly sodded lawns that have not yet rooted into the soil, or when summer patch disease is a problem. Otherwise, avoid frequent waterings that promote shallower root systems and weeds (e.g., crabgrass).
  • Water early in the day if possible.
    Given a choice, water early in the day when lawns are normally wet from dew. Avoid midday watering due to excessive evaporation, and at night due to potential increased chances of some diseases gaining a foothold. The exception to this guide is when you are in extremely hot weather and nighttime temperatures don't go below 68 degrees. Then it is better to water in the late afternoon or early evening, providing you don't have watering-time restrictions. Early or late in the day reduces the amount of evaporation that takes place during the very hot day, allowing more water to reach the root zone.
  • Spread the water uniformly across the lawn. 
    Sprinklers vary in distribution patterns, and require spray overlap for uniform coverage. Placing coffee cans or similar straight-sided containers on the lawn can help measure water application rates. Avoid flooding areas, or missing other spots. On heavy clay soils and slopes, watch for excessive runoff; it may be necessary to apply the water in several applications to allow for adequate penetration.
  • Avoid overwatering
    Use a rain gauge to measure how much water you're applying. Overwatering does more than deplete the water supply, it also makes plants prone to pests and adds to stormwater runoff, which pollutes our water systems. By choosing and operating a watering system correctly, you can reduce water bills, insect and disease problems, and maintenance requirements. For example, the more you water your lawn, the faster it grows and the more it needs to be mowed.
  • Hold off watering after fertilization and hold off fertilizing if heavy rains are expected.
    To reduce the possibility of having fertilizer wash into our water system, don't water heavily soon after fertilizing. Use light waterings to give the fertilizer the opportunity to be absorbed by the soil. Also, if heavy rains are in the forecast, hold off fertilizing until the heavy rains have passed.
  • Monitor rainfall
    Nothing looks more wasteful than running your sprinkler while it's raining. If your sprinkler system is on a timer, purchase and install a rain sensor and soil moisture sensor that automatically turns off the irrigation system. If possible, also avoid watering if rain is expected later in the day or during the next day. Your grass should be fine, even it looks stressed.
  • Do not cut lawns so short
    Two inches is too short. The cut should be 3 to 3.5 inches. Make sure your mower blade is sharp so it makes a clean cut.
  • Good soil preparation
    Good soil is essential to having a healthy lawn. Use 4 to 6 inches of good quality topsoil and add compost to provide nutrients and improve the soil texture.
  • Estimate how much water you'll need based on your soil type
    In general, 1 inch of water will penetrate sandy soils to 12 inches, loamy soils to 6 to eight inches, and clay soils 4 to 4 inches. Using these estimates isn't quite as accurate as digging, but it's pretty close, especially if you have a good knowledge of your soil composition. To figure out how long you need to keep your sprinkler or sprinkler system on, calibrate your sprinklers.

Here's a simple test to determine how much water your sprinkler system applies to your yard:

Place 5 or 6 flat-bottomed containers (such as coffee mugs, tin cans, cake pans, etc.) on your lawn. Distribute them as evenly over your lawn as possible, keeping them at least 2 feet from the sprinkler heads. Turn on the sprinkler system so that the containers begin filling with water. After 15 minutes, turn off the system. Use a ruler or tape measurer to determine the depth of water in each container. The measurements will probably be between 1/8 to 7/8 of an inch.