How to Pre-Germinate Grass Seed

Would you like to grow grass faster and with better results? Learn how to pre-germinate grass seed. It’s a simple method that requires you to soak the seeds for two to six days in a bucket with lukewarm water. 

This step-by-step guide discusses this germination-boosting technique in detail. We’ve got all the practical tips and tricks to help you pre-germinate grass seeds successfully, including what can go wrong and when to use it for the most rewarding results.

What is seed pre-germination?

Pre-germination is soaking the seed until the first root breaks the seed coat and pops out. 

It is also called partial seed germination because the rest of the germination process – after the root peaks out of the seed – happens when the seeds are already in the soil. 

Where pre-germination fits in the germination process

Here’s what happens inside the grass seed during pre-germination: As the turfgrass seeds imbibe water, their enzymes react and trigger germination. 

The energy stored in the seed during dormancy becomes available for the grass embryo, which starts growing a new plant. It sprouts its first root and pre-germination ends – this is the time to put the grass seeds into the ground.

After the pre-germinated seed lands in the soil, a leaf sheath, called coleoptile, springs out. It’s a shield to protect the first green leaf that sprouts next from the seed. The leaf grows and turns green – the grass can now make photosynthesis and feed itself. 

By this time, homeowners can enjoy vibrant green shoots on their lawns.

How to pre-germinate grass seed step-by-step

Step 1: Plan the pre-germination 

Pick the best time to pre-germinate the seed. Depending on the seed variety, turfgrass takes two to six days to pre-germinate. Once pre-germinated, seeds must go into the soil as soon as possible. 

So, before starting pre-germination, check the forecast for suitable seeding weather (mild weather, without storms, heavy rain, or wind). When you find a good spell, count back the days you need for pre-germination (e.g., 2-3 for ryegrass), and that’s your starting point. 

Prepare the seeding bed. While the seed is pre-germinating, you’ll have time to prepare the soil and ensure favorable growing conditions for your newly planted grass. Plan these tasks for the next few days:

• Remove weeds and debris. 
• Dethatch the lawn to ensure seed-to-soil contact. 
• Core aerate to loosen compacted soil. 
• Mow the lawn and collect the grass clippings (if overseeding an existing lawn).
• Spread a layer of topdressing rich in organic matter to ensure a fertile seed bed.

Determine how much grass seed you need. Measure the area you plan to seed. Check the seed package for the recommended seeding rate. Then, calculate the amount of seeds you need for your project. 

Example: Suppose you’re planting a 2000-square-foot lawn with KBG seeds. Following the University of Massachusetts recommended seeding rate of 1 to 2 lbs. per 1,000 square feet, you’ll need 2 to 4 pounds to seed the area. 

Gather your pre-germination materials. Pre-germinating grass seeds at home is easy. You only need:

• A porous material to hold the new grass seeds: a paint strainer, cheesecloth, or a burlap sack. If your seeds come in a plastic-woven bag, you can use that.
• A soaking container: a bucket, a pot without holes, or a tub.
• Room temperature water.
• Your favorite grass seeds. 
• A heavy object (e.g., a rock or a brick) should be placed on the seed bag to submerge it.

Note: Planting grass seed on a large area might require multiple buckets and strainers. Typically, you can pre-germinate about 5 pounds of seeds in a 5-gallon bucket.

Step 2: Put the grass seeds in the bag

Transfer the proper amount of seeds from the package to the seed bag of your choice. 

Tie the materials in a knot or use a rubber band to close the bag. 

Note: If you only have a few seeds to pre-germinate, put them in a moist towel in a zip-lock bag. Check the bag daily and sow the grass seeds when the root sprouts.

Step 3: Submerge the grass seeds in water

Put the seed bag into the bucket and fill it with lukewarm water. How much water do you need to soak the seeds? Add 2 to 3 parts water to 1 part seed. The bag should be fully submerged underwater at all times. 

Usually, grass seeds get wet quickly, and the bag drops to the bottom of the bucket. But sometimes, it just floats. If that happens, place a rock or any other heavy object on it to keep it submerged.

Note: Alternatively, you can put the grass seed in water without a strainer. In this case, though, draining and changing the water is a bit more difficult. 

Step 4: Place the bucket in a suitable place

Store the pre-germination container in a space that can permanently provide a warm environment, such as a garage, greenhouse, or kitchen. Dr. John C. Stier from the Department of Agriculture at the University of Wisconsin-Madison recommends keeping the bucket “uncovered at room temperature (60 to 70 degrees Fahrenheit).” 

What about light? Does turfgrass seed need sunlight to germinate? Most grass seeds don’t require direct light exposure to germinate. Mary Beth Bennett, West Virginia University Extension Service Agent, explains, “Sunlight supports germination by warming the soil.” 

Step 5: Change the water 

Remove the seed bag from the bucket and throw away the colored water. Don’t worry if there’s still a bit left on the bottom. It will dilute with the fresh water. Add room temperature water, never the cold tap water you get directly from the sink. 

The golden rule is to change the water every 12 hours. You can stretch it to once every 24 hours, but no more than that. Why is this important?

As the grass seed imbibes water, the seed coat releases germination inhibitors. In nature, these inhibitors reduce competition around the young grass plant. In a bucket full of water, they accumulate and can stop the grass seed germination process.

Changing the water also adds more oxygen. The grass seed needs it to germinate.

Alternative method: Leave the bag in the bucket only for the first 24 hours, then take it out and dunk it in fresh lukewarm water every 12 hours. Store the seeds in an empty bucket in between soakings.

Pro tip: Don’t dump the dirty water on your lawn. The inhibitors might prevent your grass from growing properly.

Step 6: Soak the seeds until they pop up

How long should you soak the seeds before planting? Generally, it takes two to six days for soaked grass seeds to shoot the first root, but the number of days depends on the grass seed species: 

• Perennial ryegrass is a fast-growing grass, requiring only two to three days of soaking. 
• Kentucky bluegrass is notorious for taking a long time to germinate. You might need to soak KBG seeds for five or six days.
• Fescues are in the middle, needing three to four days of pre-germination.

How do you know your soaked seeds are ready for planting? At a close (very close) look, you’ll notice:

• There is a little white fuzz on one end of the seed. Those are minuscule root hairs. 
• A small white shoot emerges from the grass seed – the first root.

When this happens, stop the pre-germination process and get the grass into the ground as soon as possible. Why the hurry? As grass seeds grow their little roots, they become a mass of root-entwined seeds you can’t even pull apart properly, let alone spread on the lawn. 

Step 7: Spread the pre-germinated seeds on the lawn

Pre-germinated seeds are wet. So, how do you spread soaked grass seeds without clumping up? First, hang the bag to drain the grass seeds. Don’t dry them completely; just leave them hanging for a few hours to release the excess water.

Then, mix the seeds with a solid carrier. You can use corn cob particles, granular humic acid, or sand.

To prepare the mix:

• Put the grass seeds into a wheel barrel.
• Let them dry out a bit, but not completely.
• Start adding the carrier and mixing it with the grass seed.
• Stop when the mix is dry enough to be dispersed properly with a spreader. 

You also can use a low-nitrogen, slow-release starter fertilizer or organic fertilizer.  Look for a product with clear instructions for a seed carrier mix. For example, Milorganite is recommended in a 4:1 ratio by weight (4 pounds of Milorganite to 1 pound of dry seeds). 

You’ll need to adjust the seeding rate to fit the mix you’re spreading. Weigh the mix of seeds and carrier and divide the amount by the initial quantity of dry seeds. Multiply this result with the recommended seeding rate for your turf species. 

Here’s an example:

• You bought 4 lbs. of dry KBG seeds to spread on your 2,000-square-foot lawn. The recommended seeding rate is 2 lbs. per 1,000 square feet. 
• After pre-germination and mixing with the carrier, you’ve got 10 lbs. of seed mix. 
• You divide 10 lbs. of seed mix by 4 lbs. of dry seeds and get 2.5.
• Multiply 2.5 with the initial rate of 2 lbs. per 1,000 square feet and get your final spreading rate of 5 lbs. per 1,000 square feet. 

Add half the mix to a broadcast or drop-seeder and spread it across the lawn, going back and forth steadily. Add the second half and walk the spreader perpendicular to the first direction. The application is the same as spreading granular lawn fertilizer or regular turfgrass seed.

Alternative method: Pre-germinated grass is a perfect fit for hydroseeding, which involves spreading the grass on your lawn as a mix with water and fertilizer.

Step 8: Water the grass

How do you water pre-germinated grass seed? Once the seeds are spread, water the area two to four times daily for 5 to 10 minutes each time. Provide your newly planted grass ⅛ to ¼ inches of water per day or 3 to 4 inches per week (including rainfall).

The watering method is the same as when using dry seeds, but the time window changes. You’ll need to keep this intensive irrigation schedule for a few days to a week instead of two weeks.

Once most grass seeds have sprouted leaves, gradually reduce watering until you irrigate the lawn once to twice a week with 1 to 1.5 inches of water. Depending on the weather and soil type, this can take between 3 and 4 weeks.

Seed pre-germination benefits

When you pre-germinate grass seeds before spreading them over the lawn, you take control of the most unpredictable and risky stage in your lawn’s life: successful seed germination. This comes with valuable benefits:

• Higher germination rate. Turf seeds receive all the moisture they need and perfect germination temperature. Only damaged or dried seeds won’t sprout this time, giving you the best germination rate you can expect.
• Faster germination. Properly soaking the seeds before planting reduces the germination time. For example, for KBG seed varieties, the lawn can start greening 10 days after planting instead of 14 to 30 without pre-germination. 
• Lower water usage. During pre-germination, you only use 5 to 10 gallons of water daily to keep 4 to 5 pounds of grass seed moist. If the seeds were in the soil, on a lawn of about 2,000 square feet, you would irrigate with ⅛ to ¼ inches of water per day, using roughly 150 to 300 gallons daily. 
• Fewer seeds are washed away or blown by the wind. Pre-germinated grass grows roots days earlier than non-germinated seeds, fixing into the soil and preventing the seed from being washed away.

When to pre-germinate grass seeds

You can use this method any time you seed or overseed your lawn. But the most effective is used when:

• Seeding cool-season grasses. Pre-germination helps you avoid the low temperatures of early spring, which can prevent grass seed germination and allow for earlier seeding.
• Seeding slow-germinating grasses like Kentucky bluegrass or Buffalograss. 

The best time to plant turfgrass is from late summer to early fall for cool-season grasses, with early spring as a second choice. If you plan to seed warm-season grasses, late spring to early summer is the best time to do it.

Other ways to grow grass seed fast

Pregermination is not the only technique you can use to grow grass fast. You also can speed up grass seed germination and grass growth by using:

Grass seed priming

Priming grass seeds is similar to pre-germination, except it’s done in less water and stopped before the first root emerges. In this case, you want to kick off the seed’s metabolic processes without starting germination — similar to how athletes warm up before a race. 

Professionals use a salt and water solution or a mix with polyethylene glycol to limit seed imbibition and keep germination from happening too soon.

Dormant seeding

Dormant seeding is planting your grass seeds in late fall to early winter. They’ll lay dormant during the cold season and sprout when the weather provides favorable sprouting conditions, such as warmer soil and proper moisture. 

Cornell College of Agriculture and Life Sciences says, “Dormant seedings can germinate two to three weeks earlier in the spring than conventional spring seeding.” This gives grass seedlings a precious advantage over summer annual weeds and a start with less resource competition. It also ensures healthier, thicker turf in frequently wet and poorly drained soils. 

Heating the soil

Believe it or not, you can try heating the soil to speed grass germination. No, we’re not talking about installing an in-ground heating system but about covering the soil with germination sheets to keep heat and moisture in.

You can use any plastic tarp or geotextile blankets to create a greenhouse effect and heat the ground by a few degrees. The soil temperature must be 50 to 60 degrees Fahrenheit for cool-season grasses to germinate, while cool-season turf species require 65 to 75 degrees Fahrenheit.

If you try this method, remember it is a bit riskier than the other seed-boosting strategies, and here’s why:

• If you don’t monitor the temperature carefully, the tarp can overheat the soil, killing the seeds and sprouts. 
• The moisture gathered under the tarp can trigger a fungal infection.
• Keeping the tarp on too long can prevent seedlings from accessing sunlight, limiting growth or damaging the plants.

Slice seeding

Slice seeding is a grass seeding method often used to renovate damaged lawns. It uses a slice seeder machine that pushes the seeds directly into the soil. 

Inserting seeds into the ground ensures better seed-to-soil contact and easier access to moisture and nutrients. With better germination conditions than traditional seeding, slice seeding provides faster germination and better sprouting rates.

FAQ on pre-germinating grass seed

What is the fastest-growing grass seed?

Ryegrass is the fastest-growing grass seed type, just taking five to 10 days to germinate. If you want to mix it with a slow-growing turf type like KBG, pre-germinate the slow-growing grass seed to give equal shots for both species on your lawn.

How effective is pre-germination?

Pre-germination reduces the total germination time toward the minimum necessary for your grass species. For example, perennial ryegrass needs five to 10 days to germinate. When soaked properly, the entire process is often finished in five to six days (including pre-germination), instead of eight to 10. Results depend on the weather, soil quality, and after-seeding care.

Can grass seeds germinate on top of the soil?

Yes, grass seeds can germinate on top of soil. However, germination rates can be lower if seeds are not raked into the topsoil or covered with straw mulch. Seeds that lay on the ground uncovered are more exposed to heat, dryness, runoff, wind, and birds. 

Try professional lawn seeding!

Pre-germination sounds complicated? Lawn care professionals can take the entire lawn seeding job off your shoulders. Use the Lawn Love website, find a lawn care company near you, and enjoy a ravishing green lawn without the hassle of seeding it yourself.

Main Photo Credit: VSPYCC | Flickr | CC BY 2.0