How Long Does Grass Seed Last In The Bag

How Long Does Grass Seed Last In The Bag

You clean out your lawn and garden supplies and notice a forgotten open bag of grass seed in the back. You hate to throw away a bag of grass seed if it can still be used. Can you still use it? Does grass seed expire or go bad? Keep reading to find out!

How long can grass seed be stored?

Grass seed can be stored for up to five or six years if stored properly. However, it will generally lose about 10% of its viability for every year in storage. Therefore, if the seed has been in storage for five years, it should have about a 50% germination rate.

This 10% rule is a general rule of thumb. This number could change depending on the variety of seed and how it is stored. If at all possible, use fresh grass seed when reseeding your lawn for the best results.

According to a study by Oregon State University, creeping bentgrass seeds have the most longevity. The seeds should be 50% viable even after the five-year mark. Kentucky bluegrass, tall fescue, and perennial ryegrass will be 50% viable after 3-5 years of storage.

Does grass seed go bad in the bag?

As mentioned, grass seed will become less viable over time. However, if grass seed is stored in a damp area, chances are it has mold or fungus. Always visually examine any leftover seed before using it. If you spot mold or fungus, discard the bag, and purchase a new bag of fresh seed!

How do you know if grass seed is still good?

You can be an at-home scientist with this simple experiment. Perform a germination test to see if the grass seed is still viable. Place 10-12 seeds in a small plastic bag with a damp paper towel. Seal the bag, then keep an eye on the seeds.

The grass seeds should sprout within 10 days. If only half the seeds sprout, then you know that your grass seed will probably be about 50% viable. Plant twice the recommended amount of grass seed when you reseed your lawn.

Does grass seed have an expiration date?

Just like everything else, your bag of grass should come with an expiration date. Most locally purchased grass seed will have a date printed on the bag. The grass seed expiration date indicates when the seed is most viable. It is not dangerous to use the grass seed after the expiration date; it just may not grow as well.

What’s the best way to store grass seed?

Most of us keep grass seed in our garage or shed. Unfortunately, those are not ideal conditions to store seed for longevity. The longevity of grass seed depends on the temperature and humidity of the storage environment.

The perfect temperature to store grass seed is 33-60 degrees Fahrenheit. You don’t want your seed to freeze, but you also don’t want it to get too warm. If the grass seed is stored in temperatures of 100 degrees Fahrenheit or higher, it could severely affect the grass’s viability.

Humidity is also an important factor when it comes to seed storage. Grass seed needs to have between 10 and 20 percent internal moisture level to remain viable. If the storage environment is too humid, the internal moisture level can rise above 20 percent. This can cause mold, fungus, or the grass could start to sprout prematurely in the bag. Overall, the seeds will be less viable if the level of humidity is too high.

To store seeds, seal them in resealable bags. Label them with the variety of seed and the date stored. Keep them in a cool, dark area, away from sunlight and moisture. If you’re concerned about humidity, place an open container of baking soda near the seeds to absorb moisture.


It is best to use grass seed as soon as possible. Although, with proper storage, you should be able to use that partial bag of grass seed for a few years with good results!