Sumo Gardener

Do Grass Seeds Go Bad Or Expire? | How To Properly Store Them

The question does grass seed go bad is a common one.

Unopened grass seed bags can last quite a long time, between three and five years, under the right conditions.

Properly stored opened bags of grass seed can last 18 months, if in the proper storage area.

However, you should remember that your grass seed germination rates will decrease every year that you store grass seed. 

Read on below to find out how to store correctly for a longer shelf life.

When you stumble upon three bags of unopened grass seed, you are sure to wonder does grass seed go bad? Gardeners tend to be hoarders at times.  

We find great deals on items, purchase them, and forget that they are on a shelf in our shed. It would feel wasteful to have these full bags and not be able to use them.

However, no one wants to waste their time sowing grass seed, only to realize it was bad.

Do Grass Seeds Go Bad or Expire?

Most homeowners have some grass seed stored. If you just seeded your lawn, you might want some on hand for bare patches.

You can use your own hands to spread the seeds or it is best to buy a lawn spreader. It is important to remember that grass seed has a limited shelf life.

All seeds are living organisms that interact with the air and moisture that can change the seed.

Depending on the exposure, some seeds may not germinate. The way you store the seeds will make the most difference.

How Long Does Grass Seed Last in Storage?

You can grow grass seeds in U.S. hardiness zones three through nine. It will virtually grow anywhere under the right circumstances.

The seeds are relatively hardy and can survive up to five years in the correct storage conditions. Certain varieties will only last for three years in storage.

Make sure that you look at the type and hardiness for storage. If you want a durable, storage friendly variety, select one such as perennial rye-grass.

Seeds are relatively hardy and can survive up to five years in the correct storage conditions


The proper conditions and environment are dark, cool, and an area free of humidity. Preferably, the space would be air conditioned to avoid excessive heat.

Another important factor is air flow, even if the bags are closed. The storage area should have proper air flow that circulates the bags.

It decreases moisture buildup on the bag. Keep your seeds separate from each other, ideally on other shelves.

They can create heat when near each other.It is important to remember that the longer you store the grass seeds, the germination chances reduce.

If you use grass seeds that have been stored for two years, you will need to sow the ground more heavily.

What To Avoid When Storing Grass Seeds?

Moisture is the main reason why your seeds won’t last indefinitely. When seeds were created and developed, they get moisture from the air.

However, they are harvested in dry conditions, so there is very little moisture during the storage process.

Once you open a bag, they are naturally exposed to the moisture in the air. Any additional moisture will increase the risk of fungal and rot issues, which decreases the viability of the seeds.

Also, any damaged, cracked or broken seeds will decrease in viability when exposed to moisture. Even tiny cracks let moisture into the seeds, starting the process of rotting and introduction of pathogens.

Where To Store Your Grass Seeds

The Right Location To Store Your Grass Seeds


We may find grass seed bags in our sheds, but they aren’t the ideal storage area. You want to avoid any place that the seeds may freeze. 

Unless your garage or shed is heated, you don’t want to keep the bags there.

You may want to consider your basement or cellar, as long as they are dry. Another easy area is your refrigerator if you have space, so long as it is kept between 40 and 50 degrees Fahrenheit.

How Long Do Unopened Grass Seed Bags Last?

If you find unopened bags of grass seed in your garage, you may be in luck. The seeds were sealed in the package and weren’t able to absorb any moisture from the surrounding air.

Ideally, the internal moisture level would be 13 percent. While inside of the bag, the seeds transfer air throughout the bag with no new moisture introduced.

The humidity levels aren’t high, allowing the seeds the chance to stay viable for years. Bagged seeds can still gain moisture from the outside air.

Most bags are made of porous materials. However, it happens slowly. Which allows the grass seeds to last long

How To Store Leftover Grass Seed

You may not use an entire bag of grass seed, especially if you are just filling bare patches in your yard. It is important to store the remaining seeds properly so that you can use them whenever you need to.

You need to use the right type of packaging. Something breathable, like a cloth sack or burlap bag, are perfect.

These will allow for maximum air flow without increasing the growth of mold.

Placing a container of baking soda inside of the bag can decrease the moisture introduced. Then, select the perfect area to store the seeds.

How To Store Leftover Grass Seed


About the Author Ann Katelyn

I'm Ann Katelyn, Creator and Chief Author of Sumo Gardener. Since I was a child I've always been fascinated with plants and gardens, and as an adult this has developed into my most loved hobby. I have dedicated most of my life to gardening and started Sumo Gardener as a way to express my knowledge about gardening with the hope of helping other people's gardens thrive.

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