How Often to Water Grass Seed

new planted grass seeds in soil

Proper seed irrigation makes the difference between thick grass and a patchy lawn. Here’s how often to water grass seed to grow a stunning, envy-worthy turf: Water grass seed two to four times daily until germination in five- to 10-minute sessions. Apply ⅛ to ¼ inches of water daily and adjust the watering frequency depending on the soil type, weather, and sprinkler flow rate. 

Watering often and lightly is ideal for keeping the topsoil constantly damp and preventing the seeds from drying. It’s not difficult, but quite a few details can confuse a beginner lawn owner. Read our quick guide about grass seed watering and learn how to give your newly seeded lawn the best chances to grow healthy, thick, and green.

When to start watering grass seed

gardener watering the soil with new seeds
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Experienced homeowners know planting new grass from seed takes planning and care. Here’s how to start with the right foot.

Water before you seed

A pro trick to improving seed germination rate is to water the soil before you put the seed in. The plan is to dampen the top 6 to 8 inches and store moisture for the seeds and sprouts to benefit from later. To achieve this:

  • Soak the seed bed generously a few days before you spread the turf seed 
  • Water again the day before seeding. 

Don’t overdo it. You don’t need to see puddles covering the lawn. Just apply about 1 inch of water as you would do when properly irrigating established grass

Watering the soil beforehand prevents desiccation and supports germination and deep rooting. It also improves nutrient absorption, making the starter fertilizer more effective and reducing the risk of fertilizer burn.

How do you check soil moisture 6 to 8 inches deep? Use the screwdriver test:

  • Push a screwdriver with one hand into the soil. 
  • Stop when you encounter significant resistance. 
  • Pull the screwdriver out and measure how deep it penetrated the soil. 
  • If it’s less than 6 inches, apply more water.
  • Repeat the test around the lawn to ensure it’s evenly watered.

While preparing the soil for seeding:

  • Get rid of debris and weeds and remove the thatch layer to give your grass seed a clean bed with good water absorption. 
  • Aerate to loosen the deep layers of soil. Core aeration helps water get into the soil more easily and supports deep root growth.
  • Apply a layer of topsoil 2 inches thick. Choose one rich in organic matter and minerals. It improves seed-to-soil contact, has great water-holding capacity, and comes with valuable nutrients.

Spread the grass seed across the yard with a broadcast spreader following the recommended seeding rate. Our guide, How to Plant Grass Seed, has all the details about seeding a lawn DIY. If you’re considering hiring a professional, find out what costs to expect from our Cost to Seed a Lawn article.

Pro tip: Cover the planted area with a thin layer of mulch (straw is an excellent choice). This will limit water evaporation and prevent birds from eating the seeds.

Water right after you seed

The next step is to water the seeded area. At this stage, the aim is to keep the top 1 to 1.5 inches of soil moist because that’s where the seeds lay. If that layer dries, grass seeds also dry out, and germination stops. 

Set the sprinklers to run for 5 to 10 minutes. Go for a soft flow (mist nozzles are the best choice) to avoid disturbing the seeds from their place or creating runoff. If you water manually, use a garden hose with a nozzle and do your best to water the lawn evenly.

Irrigation frequency and the right amount of water

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To ensure germination, you must keep the seeds moist. Underwatering can dry out grass seeds and sprouts, and overwatering is also an issue. Too much water can wash away seeds and lead to uneven grass growth and bare spots.

How often and how much to water 

The average amount of water grass seeds require is about ⅛ to ¼ inches per day. Water two to four times a day, and keep the sprinklers running for 5 to 10 minutes each time.

What happens if you miss a day of watering grass seeds? Each day matters at this stage, and missing a day or two of watering can dry seeds already in the germination process and kill the sprouts. That being said, you have better chances to get away with it if you live in a mild, wet climate.

Factors to consider when watering grass seed

Soil type, weather conditions, sun exposure, and lawn sprinklers can change how often you water a newly seeded lawn. 

  • Soil type: Clay soil has thin particles and holds more water. It requires less frequent irrigation. Sandy soil, on the other hand, is like a sieve. Water runs below the grass seed zone fast, so you need to irrigate the lawn more often.
  • Sun and wind: The soil dries out faster during hot, sunny days. Water at least two times a day to keep the seeds moist. Wind also supports water evaporation. If you’re dealing with temperatures in the 90s and strong wind, water three or four times a day.
  • Precipitations: Rainfall helps keep the seeds damp and put off irrigation, but be mindful of how much water it provides. Heavy rain means you can skip watering the grass seeds today. With a light shower, the soil will be dry by noon, and you’ll need to supply additional moisture.
  • Sun exposure: In shady areas, soil moisture evaporates slower, so you can water about two times a day. Soil exposed to direct sunlight loses water faster and needs additional irrigation to replace the lost moisture. Water three or four times a day to preserve topsoil moisture.
  • Irrigation system: Sprinkler flow rates can vary from 4 gpm (gallons per minute) to over 11 gpm, depending on water pressure and sprinkler type. Your lawn sprinkler’s flow rate determines how long you’ll keep the irrigation system running. 

The simplest way to decide how often to water grass seed is to check the soil. If the top 1 to 1.5 inches are dry, apply another round of water. Puddles on the lawn or soggy soil are sure signs there’s more than enough water, and you should postpone irrigation.

Grass seed watering by installation type

Overseeding an existing lawn: Established grass needs less frequent, deep watering, while newly spread grass seed requires frequent and shallow irrigation. To keep the entire lawn happy:

  • Water twice daily (early morning and mid-day) for the first two weeks after planting grass seed, with ⅛ to ¼ inches of water per day. 
  • Give your lawn a deep watering once a week to preserve deep roots.

Reseeding bare spots on an established lawn: Keep the regular watering schedule for the entire lawn area and water the seeded patches two or three times a day with a garden hose or a watering can. Spread water uniformly and avoid overwatering.

Seeding a new lawn: Set the sprinkler system to irrigate two to four times a day, depending on the weather, for 5 to 10 minutes each time. Keep this irrigation schedule for the first two to three weeks until the grass is up. 

The best time of day to water grass seed

Water grass seed in the morning between 6 a.m. and 10 a.m. Morning applications ensure proper water absorption into the soil. They also prevent moisture from lingering on newly sprouted leaves (high risk of fungal diseases) since sunlight dries the drops by lunch.

Schedule another watering session from late afternoon to early evening. If the soil gets dry during the day, add one or two more watering sessions to keep the top inches of soil moist throughout the day.

How long to water grass seed

A person watering the lawn
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Water new grass seed two to four times daily until most of it sprouts. This typically takes 10 to 14 days. Keep in mind that turf seeds don’t germinate all at once, even if you planted a single grass species. Grass sprouts in patches, here and there, depending on sun exposure and how deep the seeds are in the ground. With a seed mixture, you’ll have even more diversity.

So, how long you water grass seed depends on what type of grass you sow. Ryegrass germinates fully in about 10 days; Kentucky bluegrass can take up to a month. We’ve included a table with the most common turf types and their germination time to help you plan lawn care during this stage:

Type of turfGermination time
Annual ryegrass5 – 10 days
Bermudagrass (Seeded)10 – 30 days
Buffalograss14 – 30 days
Centipedegrass14 – 21 days
Colonial bentgrass10 – 14 days
Creeping bentgrass10 – 14 days
Fine fescue7 – 14 days
Kentucky bluegrass14 – 30 days
Perennial ryegrass5 – 10 days
St. Augustinegrass10 – 30 days
Tall fescue7 – 12 days
Zoysia14 – 21 days

Watering the grass after sprouting

It typically takes two to three weeks for a seeded lawn to green up. Around weeks 3 and 4, you’ll enjoy a green lawn with short grass seedlings covering the soil. You no longer need to keep the seed moist but feed the plants and help them develop their roots. It’s time to reduce watering:

  • Water once or a day for about a week, applying ¼ inches a day
  • Slowly aim toward watering the new lawn every other day with ¼ to ½ inches of water applied each time.

During weeks 5 and 6, transition the new grass to a less frequent watering schedule to promote deeper roots. Try to irrigate once or twice a week, but add an extra watering session if the weather is hot and dry. At this early stage in grass development, plants have shallow roots and are vulnerable to high temperatures and drought. 

Most turfgrass types are typically established six to eight weeks after planting new seeds. Continue watering the grass once or twice weekly with 1 to 1.5 inches of water. Irrigate deeply and less often, aiming to moisten the ground 6 to 8 inches deep to promote deep root growth. 

Don’t overwater. Too much moisture is harmful to your lawn, causing:

  • Shallow roots
  • Fungal diseases
  • Pest infestations
  • Weeds thriving
  • Lack of oxygen in the soil
  • Soil erosion

Pro tip: Mow the lawn for the first time when the grass is at least half an inch taller than the recommended height. Taller grass grows deeper roots and is more resilient to drought.

Tips for watering grass

Here are a few professional tips to water your lawn properly and keep it green and healthy.

  • Before planting new turf from seed, check your sprinkler system. Adjust sprinkler heads, ensure nozzles are not clogged, repair or replace broken sprinklers, and ensure even water application across the lawn. 
  • Choose a mist or an oscillating sprinkler. They are better suited for watering seeded areas.
  • Pay extra attention to lawn areas around trees. While they provide shade that limits evaporation, trees also consume a lot of water. During hot, dry spells, you must frequently water areas near trees to supply enough water for trees and grass.
  • Avoid watering the lawn in the evening. Water left on the blades at night exposes the turf to nasty fungal infections.
  • Water warm-season grasses regularly during spring and summer when they’re thriving. Reduce watering in the fall when summer grasses prepare for winter dormancy.

FAQ about watering grass seed

Why does grass seed need water to germinate?

During imbibition, the first stage of the germination process, the seed coat absorbs water and softness, making it easier to crack and let the embryo sprout when the time comes. The seed embryo uses the water to start cellular division and metabolic processes, developing into a new grass plant.

Why is my grass seed not germinating?

Your grass seed not germinating can be caused by:

  • Extreme temperatures (cool-season grass seeds germinate when the soil temperature ranges between 50 degrees and 60 degrees Fahrenheit; warm-season grass needs a soil temperature of 60 degrees to 75 degrees Fahrenheit)
  • Bad seed. Look for a brand that guarantees a germination rate of over 80%. You can also check the germination rate at home to know what to expect after seeding.
  • Not enough or too much water in the soil
  • Inadequate sun exposure 
  • Poor soil quality
  • Pests

What helps grass seed germinate faster?

Grass seeds germinate faster if they benefit from good seed-to-soil contact and proper, continuous soil moisture. 

Hire a Lawn Care Pro!

Don’t’ have time to seed your lawn or are unsure where to start such a project? Hire a pro. Find a local lawn care company with LawnStarter to plant the lawn and relax, watching the turfgrass grow healthy and green. 

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Sinziana Spiridon

Sinziana Spiridon is an outdoorsy blog writer with a green thumb and a passion for organic gardening. When not writing about weeds, pests, soil, and growing plants, she's tending to her veggie garden and the lovely turf strip in her front yard.