How Long Do You Water Grass Seed With The Sprinklers?

How Long to Water Grass Seed With Sprinkler Heads

Seeding a new lawn, or overseeding your current one, is much more intricate than simply throwing some seed down on the bare soil and hoping for lush, green turf in a couple of months.

Unlike sod or grass plugs, grass seed needs a little more attention and dedicated care. You want to give it every chance to succeed. One of the key aspects of success is watering it correctly.

I bet you are thinking to yourself, why is watering correctly important, anyway?

Water is absolutely essential for seed germination and early seedling growth.

  • Seeds are genetically predisposed to wait until conditions are right to germinate. If there isn’t enough water, they stay dormant.
  • Soil moisture softens the seed coat and activates enzymes that trigger growth.
  • The primary root, also known as the radicle, needs moist soil to penetrate the soil surface.
  • The seedling struggles to take in water until the roots develop, making it essential to have an abundance.

However, too much water can wash the seed out of the area sown. And too much water can also trigger damping off.

When it comes to new seed, it’s easy to make a mistake and either water it too little or even too much. Both of which can be detrimental. After the time and investment you put into sowing seed, you want to find the “just right” watering amount to get the beautiful, lush lawn of your dreams.

Determining the right amount of water needed isn’t a one size fits all situation. The amount varies depending on some specific factors.

  • Type of seed being grown: Different grass varieties have various moisture needs. The seeds for drought-tolerant kinds may need less to germinate than those with higher water needs.
  • Local climate: Cooler areas or areas with high humidity will need less water because they’ll lose less to evaporation. Hot, arid regions will need more.
  • Rainfall amounts: Areas with regular precipitation naturally keep the soil moist, so it isn’t necessary to supplement with as much water. Areas without frequent rain will need more water from the sprinklers.

All of this comes together in a way that makes the question, “how long to water grass seed with sprinkler heads,” one that doesn’t have an easy answer. The short answer is you need to keep the soil consistently moist without being waterlogged.

The standard recommendation for new grass seed is to water it three times a day — morning, afternoon, and evening — for the first three weeks. Each watering event should last for ten minutes to sufficiently wet the soil.

Because of the varying factors mentioned above, this recommendation is only a guideline and should be adjusted based on your situation. Start by watering three times a day for ten minutes, but keep a close eye on the soil and seed for the first few days. Watch how quickly the area dries out and look for water pooling on the soil surface and then adjust the frequency and watering duration to establish a correct watering schedule.

When To Stop Watering New Grass Seed

When Is The Best Time To Water Your Seed?

Watering your seed is important; there are a lot of factors involved in doing it properly. However, one thing I’ve seen a lot of people struggling with is the timing.

Days are usually divided into morning, afternoon, evening, and night. So, when of these four times is the ideal for watering your seeds and seedlings?

  • Grass Seed needs water as often as possible to stay moist but not water logged. If you live in a humid environment then you probably don’t need to water for very long of more often then morning, afternoon, and evening. If you live in a hot dry climate then you may need to water two to three extra times per day to keep your seed from drying out. It’s not uncommon for seeds sown in dry climates to require a light sprinkle six times per day. Depending on the volume of water your sprinkler system puts out you may need to water for ten minutes or just a single minute.
  • New Grass Seedlings usually need water twice a day. These are grass plants that have tap roots or radicles that already extend into the soil and won’t dry out as easily. For seedlings I recommend that watering is done once in the early morning and once again in the late afternoon or evening because the temperatures are cooler these times of day and the water should resist quick evaporation.
  • Established Grass usually needs more water to support bigger grass plant systems buy less frequent water to avoid fungus, disease, and shallow root systems. Mature grass plants are generally watered only once every 3-7 days depending on the volume of water hitting the soil surface, the ambient daytime temperature, and the relative humidity. Best time to water is in the morning on the coolest day of the week so that evaporative loss is minimized and so that day time sunlight can dry grass blades off before fungal threats become to great.

► See this article for more info on overwatering grass seed.

Different Sprinklers Require Different Amounts Of Time

Another aspect of seed germination has to do with the amount of water your sprinklers put out and how fine of a spray hits the ground. With a garden hose nozzle you can put a lot of water into a very small localized area quickly so it’s easy to water grass seed for only 20-30 seconds before the ground and seed is sufficiently moist.

If on the other hand you are sprinkling a seed-bed with a large oscillating sprinkler that covers a lot of area with each pass you may find that it takes 20-minutes or more to fully moisten the ground and the seed on it.

For pop-up rotary sprinklers or above ground gear drive sprinklers the head itself dictates how much water comes out; some put out a large volume of water and some put out a small volume so it’s always important to do a sprinkler test to see how long it takes for your sprinklers to put out an inch of water.

Seed doesn’t need more than a moistening of water a few times a day so if your sprinklers take an hour to drop an inch of water on the ground then you probably don’t need to run them for more than five minutes to fully water your grass seed. If your sprinkler takes four hours to put out an inch of water then a 20-min sprinkler session is probably best to ensure even coverage.

Here Are More Factors To Consider:

  • Amount Of Rainfall: The amount of rainfall your area receives after sowing the seeds is an important factor. In case of enough or excessive rains, you don’t have to water it at all. However, in case of almost no rain, you might need to water it 3-5 times a day as noted above.
  • Humid vs Dry Climate: Another factor that duration and frequency of irrigation depends upon is your climate. If you live in a humid environment then you can usually sprinkle your seed less frequently and for shorter amounts of time. Drier climates are the opposite because evaporation is faster.

How Many Days or Weeks Should You Water Grass Seed With Sprinkler Heads?

Most cool season grass types will germinate in less than three weeks and many varieties will germinate in less than ten days in ideal weather conditions. For this reason it’s best to water your seed bed like nothing has germinated for three full weeks before switching back to less frequent and deeper watering sessions.

Let the water run for about 10 minutes every watering session three to five times per day unless you are sure you have full germination. While this might seem a little excess, it is generally essential to keep the upper layer of the soil moist enough to help the plant grow freely.

Some exceptions to this would be the seeding of Perennial Rye which rarely takes longer than two weeks to fully germinate unless soil temps are particularly cold. Soil temps under 45 degrees may not ever germinate for instance.

After 2-3 weeks most seed will have germinated with the exception of some very slow to germinate varieties like Centipede for instance or other warm season grass varieties which were sown in soil with temps that were lower than 65 degrees.

Also, take special care not to over-water or underwater, these are really simple to do. In fact, a lot of people who complain about the problems seem to actually make this mistake. Calculating the amount of water properly is actually situation dependent, and if you keep these factors in mind, it should not be too hard. Just be regular with the watering, and water in proper amounts, and it would not cause any problem.

See my full grass growing guide here for more helpful tips – no opt-in needed.

Also, you may find it even more useful to see this post where I explain the time to maturity by grass type or this post where I explain when it becomes too late to plant seed in the fall.

Don’t Let Your Seed Wash Away!

Grass seed, especially newly sown seed on bare dirt or seed sown on a hillside, can easily erode and wash away. It is very important to keep an eye out for signs of seed movement and erosion because seed that is moving won’t be able to root down.

One of the best ways is to check soil erosion caused typically by over-watering. When seeding on a hillside it’s even more important to water more frequently and with less water…using a misting sprinkler on a frequent timer may be the best solution for these areas.

If you are overseeding and there is already a good amount of grass in the area you are seeding then this won’t likely be a big problem. However, if you’re trying to new grass to an area with no existing vegetation then you might want to be extra cautious to ensure that all your hard work is not washed away with your seed.

You can learn more about growing grass on a hill here.

Finally once your seed starts germinating then this is the perfect time to throw down a light application of starter fertilizer. If you want to put down the best fertilizer possible for your new lawn then make sure to see this post where I’ve reviewed a few of the best lawn starter fertilizers on the market. They beat cheap synthetics every time.