The answer is “before temperatures generally dip below freezing at night.” The biggest problem that can strike an irrigation system in the winter is water leftover in the pipes and valves from the summer freezing.
You should shut off your irrigation system just before temperatures in your region begin to dip below freezing at night. Don't shut off your irrigation system too early. Often homeowners shut their systems down as soon as the fall season arrives because they believe that their lawn requires less water.
Timing for winterizing your sprinkler system comes down to the weather. It's best to aim for the middle of fall between October 1st and Thanksgiving. You want to have it winterized before the first hard freeze of the season.
Sprinklers should be set to run for about 30 to 35 minutes at a time twice a week. Your goal is at least 1″ of water a week for your lawn.
But life happens and sooner or later the running sprinkler is forgotten – even overnight! Not only does this waste water, it's also tough on the water bill – and can cause irreparable lawn and plant damage. In fact, over-watering can cause just as many problems as under-watering.
A common rule that is followed for obstructions within 18 inches of the sprinkler deflector is the “three times rule”. This requires sprinklers to be positioned away from obstructions a minimum or three times the maximum dimension of the obstruction.
On the other hand, watering longer but less frequently, “deep watering,” produces deep roots that mean lawns can better survive periods of drought. The ideal watering schedule is once or twice per week, for about 25 to 30 minutes each time.
Avoid watering grass on a hot afternoon when it's 95 degrees or higher. The best time to water grass is at dawn or in the early evening. Water deeply three times a week instead of a little water daily. Test whether your sprinkler system is watering your lawn evenly.
Water Wisely
Most lawns need to be watered no more than three days a week in the spring as well as in the summer and two days a week in the fall. This watering schedule is recommended under normal water supply conditions.
If your sprinkler output is 1½ inches per week, your sprinklers should run for only ⅓ hour or 20 minutes that week (½ divided by 1½). On a twice-weekly watering schedule, run your sprinklers 10 minutes each time.
Luckily, you can avoid frozen and burst irrigation pipes. To keep your investment functional, make it an annual habit to winterize your irrigation system. Simply drain the system and shut it down when you're done watering for the year.
Running the sprinkler system when it is 32 degrees Fahrenheit or below is cause for concern. Let's take a look below at the best ways to protect your sprinkler system in the winter months.
However, if the temperatures do dip down into the 20's, or temperatures remain below 32 degrees for an extended period of time, your irrigation system can be damaged.
During the periods of prolonged winter drought, if the air temperature is above freezing and the soil isn't frozen, you should water every two or three weeks for 15 to 20 minutes – just enough to provide moisture to the crown and roots of the plants and counteract the drying effects of winter winds.
Between irrigation and natural rainfall, your grass should receive between 1 and 1.5 inches of water each week during the summer. Water deeply every other day for the best results.
It's important to water deeply and infrequently to encourage deep root growth and drought tolerance. Most grasses require about 1-2 inches of water per week, which can be achieved through one or two deep watering sessions. Overwatering can lead to shallow root growth, disease, and pest problems.
Watering in the morning (before 10 a.m.) is the best time for your lawn; it's cooler and winds tend to be calmer so water can soak into the soil and be absorbed by the grass roots before it can evaporate.
Typically, most lawn irrigation periods during the summer should last between 25–30 minutes each. This amount of time depends on a lot of different factors though. As previously stated, each irrigation system or sprinkler can deliver different amounts of water and it's important to hit that 1 inch per week requirement.
In times of extreme heat, it is vital to water your lawn for about 30 to 45 minutes daily. Once the temperatures drop below ninety, you can cut back to watering three to four times a week, until that blissful thunderstorm comes and quenches your lawn's thirst!
Most lawn experts recommend watering your grass until the soil or ground temperature reaches the 40-degree Fahrenheit mark.
Can You Water Grass After Mowing? Yes, you can water grass after mowing, however it is healthy to water it but only if it requires it. Watering will help the mowed blades perk up and survive being cut better. Take care not to water a lawn overwatered or from noon till late into the night.