How Long to Water New Grass Seed With a Sprinkler?

When you plant new grass seed, it’s a process of patience and taking the right steps at the right time. Balance is the name of the game, especially when it comes to water content in the soil.

When using a sprinkler, following a watering schedule will keep the ground moist enough to start the germination process and grow your seeds to a green, healthy lawn.

Water And The Seed Germination Process

Water initiates a seed’s germination process by soaking the outer casing of the seed in the right amount that allows the embryo to absorb water and begin to sprout.

It’s vital for seeds to get just enough water, not too little or too much. You can over water newly planted grass seed and drown them or wash away your fertilizer or soil, while the seeds will die in too dry of conditions.

Water and the soil’s nutrients provide the seeds with the building blocks of roots and blades of grass. Making sure the soil profile and moisture content is ready to accept seeds will help your new lawn grow to healthy, dense coverage.

Preparing The Soil For Seeds

Preparing The Soil For Seeds

The soil should be prepared a few days in advance of sowing grass seed to make sure the seeds receive enough water, air, light, and nutrients. There are a few key things you can focus on to be sure the soil is ready:

  • Aeration – Whether you’re overseeding your existing lawn or replanting on bare soil, the topsoil should be well-aerated for the seeds to have the best growing environment. Soil with lots of space for oxygen and water will also give the roots room to stretch and establish a firm hold in the ground.
  • Nutrient profile – Planting seeds is a good opportunity to apply fertilizer to the yard, and if you’re tilling, to mix it into the topsoil. Perform a soil test before adding fertilizers, but if your lawn is well-kept, the grass should be regularly using up the soil’s nitrogen, phosphorus, and potassium and will need replenishment.
  • Drainage – Compacted soil doesn’t absorb water, and it doesn’t drain well when it does receive some. Well-aerated soil is more porous and can drain water faster, ensuring that seeds don’t drown and that roots reach deep. Depending on your yard’s soil type, you can also add sand or compost to the topsoil to help it drain better and build the soil’s structure.

Checking Soil Moisture Content

Making sure the soil is wet deep enough is a key factor in the success of your seeds’ growth period. You can use a soil probe, a ruler, or a screwdriver to stick into the ground as an easy way to make sure the soil is moist enough up to 8 inches deep.

Topsoil should be moist but not wet. After you sow the seeds, covering them with mulch or hay will help prevent evaporation, holding in water in to keep the soil moist. Putting down netting can help keep mulch and straw from blowing away and help keep birds from getting to your seeds at the same time.


Using a sprinkler is one of the best ways to irrigate your lawn, whether you’re planting seeds or just watering the grass. Using timers and smart devices makes it even easier to be sure the lawn is getting the water it needs.

Other than keeping to a watering schedule, making sure the sprinkler applies water equally across the yard is one of the most important things to pay attention to when using one. The type of sprinkler you use makes a difference in how water is spread:

  • Hose-end: oscillating lawn sprinklers and tripods are usually connected to your house, and if your lawn is large enough, you’ll have to move these around to be sure all areas are getting enough water.
  • Pulsating: spike lawn sprinklers may be connected to a hose or an in-ground irrigation system, and these shoot water out. Some models can shoot water over 50 feet, able to cover a larger area than other types.
  • In-ground: an in-ground irrigation system is laid under the soil and will have to be moved if you’re tilling the yard. When you plant new grass or overseed your lawn, in-ground systems will apply water evenly with multiple spouts covering their own area, usually in a full 360-degree spray. These are connected to a system control panel with a timer.

Water Requirements for Grass

A mature lawn needs about 1 inch of water per week, including from rainfall. The amount of use you get out of your sprinkler will be based on the weather your area experiences at the time of planting.

That 1 inch of water per week will keep the top 6 to 8 inches of soil moist enough for your mature lawn. When you grow seeds, however, the soil surface needs to be kept consistently moist for the critical growth period of the grass roots and first sprouted blades.

How Often To Water Grass Seeds

Your grass seeds need frequent watering to grow into lush lawns. The rule of thumb for watering grass seeds is to do it ten minutes at a time, twice a day during germination: once in the morning and once in the evening at the coolest parts of the day, so the water won’t evaporate. 7 am and 7 pm, or thereabout, should keep your soil at a consistent moisture.

Once the seeds have sprouted, watering once a day in the morning will be enough to get your grass to mature coverage.

Using a rain gauge will help you measure how much water your seeds and soil are getting over a day and per week since the requirements will change during the different phases of planting and growing new grass:

  • Before planting grass seeds – 2 to 3 days before planting grass seeds, water 6 to 8 inches deep every day so the seeds won’t be planted in dry soil.
  • Right after planting – You should water grass seed right away so that the husk can soak and the embryo can receive the hydration to begin the germination process. Get the soil moist about 4 inches deep.
  • During germination – You should water the lawn every day after seeding for up to 6 weeks: twice a day for the first 3 weeks and once a day for the last 3. While the seeds are growing, they should receive 3 to 4 inches of water per week, or about half an inch a day.