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Watering Tips

The Best Time of Day to Water

When is the best time of day to water? This is one of the three most asked questions we here from our customers, along with how much or how often to water.

The single best time of day to water is early morning. More specifically, pre-dawn, just before the sun comes up. Between 4 a.m. and 6 a.m. Here's why.

In school we all learned about photosynthesis. The definition of photosynthesis is the process by which green plants and certain other organisms transform light energy into chemical energy needed for life. The key words here are photo and light. Photosynthesis can't take place when light is not present. The plants will just sit in water they can't consume. The same goes for fertilizer. Plants can't utilize any fertilizer when it is dark.

Important Reasons To Water In The Early Morning

  • Pre-dawn watering allows the water to leach down to the root zone just in time for the sun to come up when the plants can use it.
  • Evaporation is minimal in the pre-dawn time period.
  • Wind is at it's lowest in the early morning. Wind can cause your sprinkler system to be very inefficient. The wind distorts the spray pattern reducing coverage. It also carries a percentage of the water away from the intended target, into the atmosphere or onto undesirable surfaces, such as walkway and driveways, hence you end up wasting water.
  • Water pressure. A lot of professionals claim that water pressure is highest at this time of morning. While this may be true, in Dallas Texas, the water pressure does not fluctuate enough for this to be a factor.
  • Early morning watering gives the plants the most hours of sunlight to use the available water and nutrients in the soil.
  • To better understand why early morning watering is best, understanding why not to water at any other time will make the point perfectly clear. Let's look at the downside of watering at any other time.

Evening & Nighttime Watering (The worst time to water)

  • Night watering is inefficient. A certain amount of the water that goes into the soil during the dark hours will leach past the root zone by the time the sun comes up and can never be used by the plants. This is a waste of water.
  • Disease and fungus thrive in dark, wet environments. It is not good for plant and lawn leaves to be wet all night. Your plants will be under attack in this situation. Mushrooms in lawns are caused by night watering. Watering in the morning allows plants to quickly dry off keeping them safe from disease and fungus.
  • Mold also thrives in damp, wet environments. Overspray onto the outside of the walls of your home, if left wet all night, can cause mold to grow onto the interior of the walls and even onto the drywall inside the house. This can be a particularly dangerous health condition as well as costly to correct.
  • Algae forms when surfaces are wet at night. Overspray from your sprinklers onto concrete and stone walks and driveways, garden walls, stucco walls, painted walls, and other hardscaping will cause algae to grow when wet all night. Watering every day can also cause this problem. Also, unwanted moss grows in gardens and lawns when watering occurs at night.
  • Dry rot is caused by wood surfaces being wet for long periods of time. Sprinkler overspray onto wood surfaces need to dry out between waterings or dry rot will occur. Allowing wood surfaces to thoroughly dry out between waterings will reduce if not altogether eliminate dry rot from sprinkler overspray.
  • Rust on wrought iron fences, gates, etc. will grow at an accelerated rate if they become wet from sprinklers at night. Watering in the morning means they will dry off as quickly as possible thereby reducing or eliminating the growth of rust.

As you can see, watering in the evening or nighttime has so many negatives there is no reason for doing it. The only advantage claimed by the night watering proponents is the evaporation factor. However, evaporation in the early morning, pre-dawn hours is so negligible; it completely outweighs the detrimental effects it has on your lawns, plants, and over sprayed surfaces.

Late Afternoon Watering

Late afternoon is not a good time of day to water. Here's why.

  • Watering in the late afternoon and early evening will limit the number of hours the plants can conduct photosynthesis.
  • Leaching
  • Plants that are still wet when darkness comes will be more susceptible to disease and fungus as stated above.
  • Hardscaping, wood, wrought iron, walls, etc. that remain wet when darkness comes will have the unwanted effects as listed above.
  • Wind is usually at it's highest in the late afternoon and early evening hours and will cause the problems stated above.

Midday Watering

Midday watering is not recommended for the following reasons:

  • Evaporation is the highest in the middle of the day. You will have to increase the duration of watering considerably just to make up for the evaporation. This is a waste of water, a waste of water that will show up on your water bill.
  • Wind. Although not a high as in the afternoon, might be a factor in the middle of the day. Not good for reasons stated above.
  • Damage to lawns and plants. Watering in the midday is not harmful to lawns and plants. Lawns will not burn. The one exception would be in extremely hot temperatures over 90 degrees.

Mid-morning Watering

If you can't water in the early morning, the next best time to water using your sprinkler system would be in the mid-morning hours. From about 7 a.m. to 10 a.m. The temperature is still relatively low and therefore evaporation is low. Winds are unusually calm at this time of day. The plants have plenty of time to dry off and soak up the sun and nutrients. Surfaces that receive overspray from the sprinklers have plenty of time to dry off. Some of the reasons homeowners will elect to water during this time frame is that the newspaper gets wet, and the homes plumbing or the sprinklers themselves make enough noise to wake-up residents, usually just before their alarms go off. Another reason to not water between the hours of 4 a.m. to 6 a.m. is that if the sprinklers are running at the same time as residents are taking showers, there may not be enough water pressure to run both the sprinklers and showers at the same time.