How do you know if grass seed is still good?

Knowing if grass seed is still good to plant is important for having a lush, green lawn. Old or spoiled grass seed simply won’t grow. This article will provide tips on how to test if your grass seed is still viable so your planting efforts aren’t in vain.

Check the Expiration Date

The first thing to look for when checking if grass seed is still good is the expiration date. Grass seeds typically last around 2-4 years when stored properly. However, the germination rate starts dropping after the first year. So seed that is 3-4 years old may grow, but have a lower germination rate than fresher seed.

An expiration date is usually stamped or printed on the seed packaging. If there’s no date, you can look up the expiration time for that seed type online to get a rough idea of its age. Any seed that is past its expiration date is risky to use and likely won’t grow well, if at all.

Inspect the Packaging

In addition to the expiration date, inspecting the actual seed packaging can provide clues about the seed’s viability. Here’s what to look for:

  • Packets or bags that are torn or damaged could mean the seed got wet or exposed to air, humidity and heat which can cause it to expire quicker.
  • Bags that are puffed up or bulging may indicate moisture got inside and spoiled the seed.
  • Check for any visible mold, mildew or clumping which are signs the seed has been exposed to moisture and gone bad.

If the packaging appears damaged, puffed up or shows any signs of moisture, don’t bother planting that grass seed as germination is unlikely.

Examining the Actual Grass Seeds

Opening up the seed packet or bag and examining the actual grass seed inside provides the best clues about viability.

Here’s what to look for when inspecting grass seeds:

  • Color – Viable grass seed should be fairly uniform in color. If some seeds appear off-color or yellowed, that can indicate spoilage.
  • Softness – Healthy grass seed feels hard. Take a few seeds and pinch them between your fingers. Soft, mushy seeds mean the seed has expired and won’t sprout.
  • Clumping – Grass seeds should flow freely when poured. Clumped or stuck together seeds suggest moisture was introduced and ruined the seeds.
  • Odor – Fresh grass seed has an earthy, grain-like smell. Rancid, rotten or musty odors mean the seed has gone bad.

Any of these signs indicate the grass seed has spoiled and won’t germinate successfully. Toss these out and get fresh seed.

Try a Germination Test

For the most definitive test of grass seed viability, perform a germination test. This involves planting a sample of seeds and seeing how many sprout.

Follow these steps:

  1. Take a paper towel and dampen it with water.
  2. Spread out 10-20 seeds evenly on half of the towel.
  3. Fold the empty half of the towel over the seeds.
  4. Place the towel in a plastic zip-top bag, seal it, and put it somewhere warm.
  5. Check daily and keep the towel moist – don’t let it dry out.
  6. After 5-10 days, count how many seeds have sprouted. Calculate the percentage.

If less than 80% of the seeds have sprouted, the germination rate is too low and that grass seed is past its prime.

Buy New Seed Each Season

To avoid having to test old grass seed, it’s smart to simply buy fresh, new seed each planting season. Only buy enough that will be used in one season.

Store leftover seeds in a cool, dry place in an airtight container. Never leave seeds sitting in a hot shed or garage between seasons.

Buying new seed every spring ensures you start with the highest quality, most viable seeds with the best chance of establishing a lush lawn.

Look for Signs of Quality Seed

When purchasing new grass seed, look for signs you’re getting fresh, high-quality seed:

  • Reputable brand name
  • Seed packaged for the current year
  • Harvest date on packaging
  • Certified seed blend
  • No signs of damaged packaging
  • Purchase from a trusted garden center

Higher quality seed costs a bit more but is worth it to ensure your lawn gets off to the right start. Check packaging dates and only purchase current season seed.

Proper Seed Storage

Storing grass seed properly is key to keeping it viable as long as possible. Follow these tips for ideal seed storage:

  • Keep seed in a dark, cool, dry location ideally between 40-75°F.
  • Avoid direct sunlight, heat, humidity and moisture.
  • Use original packaging or tight-sealing containers like Tupperware.
  • Don’t store seeds in the garage or shed where temperatures fluctuate.
  • Refrigeration can extend seed life if stored in airtight containers.
  • Throw out any clumped, musty or expired seed.

Following proper storage methods can help grass seed last up to 4 years, avoiding waste and the need to test old seeds.

Indicators Seed Has Gone Bad

Here are the top signs that indicate your grass seed has expired and won’t sprout:

  • Expired use by date
  • Damaged, puffed up or torn packaging
  • Visible mold, mildew or clumping
  • Rancid, musty or rotten smell
  • Off-color or yellowed appearance
  • Seeds feel soft and mushy
  • Germination test shows low sprouting rate

If your grass seed exhibits any of these, don’t bother planting it. You’ll end up wasting time, effort and money on seed that won’t grow. Follow the tips in this article to ensure your grass seed is viable and ready for planting.

Frequently Asked Questions

What is the shelf life of grass seed?

Under proper dry, cool storage conditions, grass seed typically lasts 2-4 years before the germination rate starts dropping. The expiration date is usually stamped on the packaging but seed can go bad quicker if stored improperly in heat or humidity.

Can old grass seed be re-used?

It’s risky to use grass seed that is more than 1-2 years old, even if stored properly. The germination rate declines over time so old seed can result in spotty, sparse grass growth. It’s best to start each growing season with fresh, new grass seed.

How do you revitalize old grass seeds?

There is no reliable way to revitalize expired or old grass seeds. Methods like soaking in water, fertilizer or nutrient solutions typically do not improve germination rates enough. It’s a myth that old seeds can be revived. The best policy is to discard old seed and buy new.

What can damage grass seed viability?

Moisture, heat and humidity are the main culprits. Exposing grass seeds to water, high temperatures or humid conditions can quickly damage viability leading to mold, mildew and spoilage. Direct sunlight can also be harmful over time. Proper cool, dry storage extends shelf life.

How do I prepare for planting grass seed?

Key steps when preparing to plant grass seed include loosening the top layer of soil, removing debris, leveling the area, applying starter fertilizer if needed and timing planting just before rain or watering. Using fresh, quality seed suited for the climate and conditions is also vital for seeding success.


Checking your grass seed’s expiration date, inspecting the packaging and doing a germination test are foolproof ways to determine if seed is still viable. Dry, cool storage can help properly stored grass seed remain lively for 2-4 years. But it’s always a safer bet to start each growing season with new seed for the best lawn results. Following the tips in this article will give you green grass, not wasted time and effort.

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