How Long Can Grass Seed Be Stored? A Complete Guide!

BackyardBooster.com is reader-supported. When you buy through links on our site, we may earn an affiliate commission at no added cost to you. Learn more.

Got some leftover grass seed? Make sure it doesn’t go to waste. How long can grass seed be stored? If you store it properly, you can use it to patch your lawn for years to come.

Getting your lawn to look great isn’t easy, and continuously buying grass seed can be expensive.

Storing grass seed is an easy way to ensure you have grass seed whenever you want to reseed a patch of bare lawn. You can also store leftover seeds to use in the next season.

Does my grass seed expire? Does my grass seed stay good forever? Unfortunately, no. But there are a few things you can do to prolong the life of your grass seed. 

The usefulness of grass seed is highly dependent on how it is stored. Therefore, it’s crucial to provide grass seed ideal conditions during storage.

This article describes the lifespan of grass seed, their storage method, maintenance, and everything else you need to know about storing grass seed for long periods.

How Long Can Grass Seed Be Stored?

In general, fresh grass seed can be stored for three to five years. However, the shelf life of grass seed depends on the plant’s health that produced them, the type of seed, and the storage conditions.

The unused seed typically remains fully viable for up to one year after the test date mentioned on its original packaging.

However, grass seed may go bad earlier if it is not stored properly.

The germination rate of grass seed decreases by 10% to 20% per year even if you keep the seed in the ideal storage conditions. For instance, if the new seed’s grass seed germination rate was 90% when you stored it, it will drop to around 80% in two years. It will keep decreasing with each additional year.

Shelf life also depends on the grass seed type.

Kentucky bluegrass, tall fescue, and perennial ryegrass seeds expire earlier than the creeping bentgrass seeds. 50% of these seeds will germinate after 3 to 5 years of their storage.

On the other hand, 50% of creeping bentgrass seeds will germinate after five or even more years.

How To Store Grass Seed Properly?

Properly storing grass seed is key to maintaining their viability. Many people lose viability of their grass seeds by up to 50% because they store them in poor conditions and do not maintain them throughout the storage period.

Let’s find out how to properly store grass seed.

Dry Grass Seeds

If you have not opened the bags of grass seed and they are intact, then it is best to keep them in the same plastic bag and store them as it is in a place that is free of rodents, mice, etc.

On the other hand, if the grass seeds are freshly picked, it is essential to dry them before placing them in a sealed container.

Excess moisture and high temperature are considered the biggest enemies of the stored seeds. Regulating moisture and temperature is the best way to keep your seeds in good shape.

There are several methods you can use to dry the grass seeds. No matter which method you use, make sure you do not apply excessive heat to dry them.

The best method to dry the fresh seed is to allow them dry naturally.

You can spread seeds on a paper towel, tray, plate, or any other similar utensil and place them in a safe area for a few days.

You can speed up the drying process by turning on the fan. The increased airflow will remove the moisture faster. As a result, your grass seeds will be dried in 2 to 3 days maximum.

Store In A Suitable Place

Now comes another important part. Storing the seeds carefully can keep the seeds viable for years.

First, select the bag or container in which you are interested in placing them.

Use a breathable bag like a burlap bag or a cloth sack. They allow air circulation, keep the seeds fresh, and prevent mold development.

Now you need to decide the storage area. Keep three words in mind while determining the grass seeds’ storage area: dry, cool, dark.

The place should be dry so that the seeds do not absorb moisture and develop mold.

It should also be a cool place, so the seeds do not overheat. Freezing temperatures or very hot temperatures can kill the seed embryo. Therefore, you’ll avoid places like a freezing garage or a hot shed.

A dry, dark place like a basement or cellar is a good storage area and will provide the best results.

The area should be safe from pests, rodents, and mice. If they can get access to the seed storage bag, they will not think twice before destroying the bag.

TIP: You can store the seeds in a refrigerator as well. If using a refrigerator, place a commercial desiccant or baking soda with your bag of grass seed to keep them protected from moisture.

Some additional tips for storage to ensure your seeds remain viable:

• Write seed-related details on the storage bag, so you do not have trouble the next time you are looking for a particular grass seed type.
  
• Write the expiration date provided on the original packaging, the date you stored them, the weight of the seeds, and the type of seeds.
  

Which Factors Affect the Viability of Stored Grass Seeds?

Now that you have stored the seeds properly, it is important to maintain their viability to use them in the future. Keep in mind the following tips for maintaining your grass seed’s viability over the years.

Moisture Content of the Seed

Moisture present inside the seed plays several roles. For example, high moisture levels can increase the rate of metabolism (reactions occurring inside a cell), the rate of respiration, and the chances of mold development.

All these things contribute to the weakness of the seed and the death of its embryo. That is why managing moisture is very crucial for the health of grass seeds.

Do not store freshly picked seeds as it is. Make sure to dry the seeds as it significantly reduces their moisture levels.

Dry them until their moisture level drops below 13%. If the relative humidity of the air present around the seeds is high (particularly in winter and fall), the seeds will absorb moisture from the air, and their moisture content will increase.

Under such conditions, you’ll need to move them to an area with low relative humidity or make sure they avoid contact with the air. See Relative Humidity.

Storage Temperature

Storage temperature and humidity levels are somewhat linked. And both contribute to how long grass seed can be stored.

Experts recommend that the sum of relative humidity and temperature of the surroundings should not be more than 100.

For instance, if the relative humidity is 50% and the temperature is also 50 degrees Fahrenheit, the sum would be 100, which would be an acceptable storage condition for the old grass seed. However, this rule is meant to be a general guideline and not a definitive cutoff.

The seed’s storage temperature should not be more than 60 degrees Fahrenheit or below 32 degrees Fahrenheit. Storing the seed at a temperature higher or lower than the temperature mentioned above can kill the seed embryos more or less.

You should keep a thermometer in the storage area to make sure the seeds stay at the desired temperature. See below for a great tool that monitors both the temperature and humidity.

Relative Humidity

Grass seeds can absorb moisture from their environment and release it back due to the airflow.

Seeds stored in the sealed container maintain their moisture content throughout the storage. This is because there will be very little air space around them, which means that the relative humidity will be nearly equal to the seeds’ moisture content.

On the other hand, seeds stored in breathable bags will bring equilibrium between their moisture content and the humidity of their surroundings. Therefore, the moisture content will vary according to the moisture in the air.

You should store grass seeds in a dry place or an area with a relative humidity of no more than 60%. Keep a hygrometer (our favorite) in the storage area to measure the humidity of the storage area from time to time.

Storage Duration

Seed germination rate decreases over the years. Older seed tends not to perform as well.

The longer you store them, the fewer seeds will germinate when sown. Seed embryos tend to die off over time no matter the storage condition, but you can help prolong their life.

Seed embryos are sensitive parts that need specific conditions to survive. For example, any fluctuation in the moisture or temperature can cause the seeds to die.

The health of all embryos of even the same bag differs from each other. A seed obtained from a healthy plant grown in very favorable conditions tends to perform better than the seed whose parent plant was grown in poor conditions.

Storage Insects and Fungi Protection

Storage fungi and insects can ruin the crops and seeds completely.

The most common storage fungi species belong to the genera Aspergillus and Penicillium. They can grow at seed moisture levels of even 6%.

The best practice people use to keep their grass seeds protected from fungi and insects is keeping the moisture levels low and placing the storage bags in an area free of insects.

Make sure you do not have anything that would attract insects nearby.

Tips for Preserving Grass Seeds for Next Season

Below are the expert tips you should follow to increase the longevity of your stored grass seeds.

• Dry the seeds naturally.
  
  
• Spread them in a safe place.
  
  
• Avoid direct sunlight because it can damage the sensitive embryo.
  
  
• Indicate the storage date and seed type on the storage bag or container. This way, you will not have any trouble telling which container has which kind of seeds or how long you have been storing them.
  
  
• If the seeds are stored in the refrigerator, do not open the storage container immediately after removing it from the fridge. Opening the container immediately after removing it from the refrigerator can cause the moisture to condense on the seeds. Keep the closed container aside for a few minutes and let its temperature drop to room temperature.

How Do You Know If Grass Seed Is Still Good?

It helps to check the viability of old seeds before using them in your new lawn or bare spots on your lawn. If you’re using seeds that have gone bad, you’ll be setting up your lawn for failure. The two popular methods of checking seed viability are described below.

Perform A Water Test

The water test is straightforward and easy. Take a water container and put your old grass seeds in the water. Give seeds 15 minutes to sit in the container. Seeds that sink are good to go. On the other hand, seeds that float are dead and will not sprout when sown.

Perform A Germination Test

A germination test takes a little longer but can give you more accurate results.

1. Take a paper towel and wet it until damp.
   
   
2.  Take ten old grass seeds from the storage bag.
   
   
3. Place them carefully on the damp paper towel.
   
   
4. Now fold the paper towel and place it inside a plastic bag.
   
   
5. Keep this bag in a warm and safe area and give seeds a few days to grow and germinate.
   
   
6. Keep checking the dampness of the paper towel. If you think it has dried out, then wet the paper towel again.

If more than 50% of the seeds germinate, it means your storage bag has a good number of viable grass seeds. But if the number is less than 50%, then it means there are fewer viable seeds left in the storage bag.

If you have a good germination rate, you’ll see your seeds sprout when you plant them. If you have expired grass seed, you can throw it out.

Conclusion

You can store grass seeds for years and keep them viable if you provide them healthy storage conditions. Cool, dry, and dark places are preferably better for storing grass seeds.

If using freshly-picked grass seeds, be sure to dry the seeds thoroughly to reduce their moisture content. It will reduce their metabolism rate and the chances of the development of mold infections.

Get out there and plant your grass seed! And now that you know how long grass seed can be stored, make sure you store your leftover seed properly!

Find out if your potting soil can go bad!

Frequently Asked Questions (FAQs)

Does grass seed go bad when frozen?

Yes, grass seeds can go bad when they are frozen. At freezing temperatures, the moisture that seed cells need to survive gets crystallized, which results in cell death and eventually the end of the seed’s life. Avoid storing grass seeds below 32 degrees Fahrenheit.

Can I store grass seed in the garage?

You can store grass seeds in the garage as long as it has relative humidity below 60% and temperature between 32 and 60 degrees Fahrenheit. Garages are usually colder during the winters. For this reason, it is better not to store leftover grass seeds in garages if the temperature is unregulated.

How long does grass seed take to germinate?

Grass seeds generally take 7 to 30 days to germinate. The speed of germination depends on several factors like air temperature, soil temperature, soil content, seed condition, seed type, etc. Planting new grass seed takes a lot of understanding and care.