Does Grass Seed Go Bad? – How to Properly Store Them?

This post may contains affiliate links. If you click and buy we may make a commission, at no additional charge to you. Please see our disclosure policy for more details.

You may have purchased some extra grass seed and left it in the shed. These grass seeds, whether planted or dormant, are yet alive. When exposed to the open air, they react with the environment. Even well-packed seeds that stay in the bag can undergo cellular changes.

Some old seeds may germinate, some may die upon germination, and the rest won’t germinate at all. There are a bunch of factors that affect the potency of grass seeds. The temperature and humidity in the room, type of storage container, seed type, etc. will impact their shelf life.

How Many Years Can Grass Seeds Last?

properly store grass seed

The majority of grass seeds can last for five years, although certain seed types will fail to sprout after three years. Be warned; the germination rate can begin to get affected after two years of storage.

Typically, each year that your grass seeds spend in the bag, they lose approximately 20% of their initial germination rate. In short, the fresher the seeds, the more convenient and healthy a germination process.

Ryegrass seeds can stay potent for up to 5 years, whereas other varieties such as Bermuda grass and fescue grass lose their potency a couple of years sooner.

How to Properly Store Grass Seeds?

properly storing grass seeds

Properly storing grass seeds primarily requires the place of storage to be cool and dry. Freezing temperatures and areas exposed to heat will kill the growth cells in your seeds faster than otherwise.

The precautions you account for when storing grass seeds will contribute to whether or not they are viable in the long-term. Try and keep track of the following factors:


taking care of grass seed

Based on the species of seeds, the seed’s moisture content can vary. 15 to 20 percent is considered an optimal moisture level for most seeds. It is your job to ensure that they don’t lose this moisture. A couple of weeks of exposure to humidity can extract the moisture and kill the seeds.

On the other hand, if additional moisture gets to your seeds, they are good as dead in a year. The fact that this only happens when the storage atmosphere is humid should tell you a lot. If the seeds are protected from humidity, they are also protected from losing or absorbing excess moisture.

As long as there is plenty of dry air, there is no chance of moisture leading to rotting and fungal attacks within your seeds.


grass seed go bad

A moderately cool temperature condition will do a great deal in preserving the potency of grass seeds. Anything between 50 to 60 degrees Fahrenheit is the ideal temperature for stored seeds. In case your seeds are exposed to temperatures over 100 degrees Fahrenheit, they would ultimately die out within a month or two.

Being a gardener, you would prefer to store grass seeds in the shed. Make sure to keep a constant check of the temperature in your shed. Whenever it’s too hot or too cold, you must make the required storage adjustments.

In case you decide to store grass seeds in the refrigerator for the lack of a better place, be sure to add a desiccant. Desiccants will contribute to eliminating the extra moisture and keeping the area dry.

Similarly, when you store your seeds in such closed areas, you must cut open the bag and place an open container of baking soda or some kind of desiccant.


if your grass seed go bad

Don’t just keep them in your garage or garden shed. Consider keeping them in an indoor closet or your basement. As long as the location is dry and free of moisture, grass seeds can be stored for longer.

Most importantly, make sure rodents, and insects cannot access your seed bag location. Irrespective of your seed type and age, these little creatures will make a delicious meal of it, especially in the winter season. Keeping these seed bags off the floor can help avoid rodents.

An ideal situation would be a storage area that is cool, free of humidity, dark, and also has an air conditioner. This evades the problem of excessive heat collection.

Type of Storage

if your grass seed goes bad

You can either store your seeds in a sealed package type container or a sack/bag.

A sealed package type is the preferred option as moisture cannot leave or enter the package. The moisture amongst the seeds, even if released, will have no place to circulate except for in the bag itself. As long as the container is airtight and not of a porous material, the problem of humidity does not exist.

Seeds stored in a sack/bag tend to allow outside air to enter and let the inside air leave. Firstly this leads to the seed moisture content being free to circulate out of the bag due to the typical porous design.

Secondly, in case there is any wetness and leakage in the storage area, although the bag may be airtight, humidity sticks to the bag’s outer layers. This slowly gets to the seeds and disrupts their moisture content, eventually leaving them dead.

Consider using sealed bags for grass seeds in case you have leftovers (small amounts). This will make sure your seeds are sprout-worthy for a more extended period.

Can I identify Expired Grass Seeds?

if your grass seed bad

There is no thumb rule to identify expired grass seeds. Look for the tested date/expiry date of the seed bag, and this should give you an approximate idea of whether your seeds will grow or not.

Although if the majority of these subtle elements are visible, then the odds are the seeds are expired:

  • Any bump or clumps. Even the slightest of them can indicate expired seeds. Look thoroughly.
  • Any kind of discoloration on the seeds is unhealthy. It could also be an indicator of fungus forming inside the seed bag altogether.
  • Any sort of unusual smell from the seeds could also indicate expired grass seeds.
  • Seeds that are cracked open or face structural damage have lost their moisture content and would not germinate.

How Should I Store Leftover Grass Seeds?

bad grass seed

Large amounts of leftover grass seeds should be kept in a cloth bag. As cloth bags provide breathability, there is continuous airflow, and mold cannot form. Also, place a container of baking soda inside this bag for absorbing the moisture coming in through the pores.

If you have small amounts of leftover seeds, then a sealed package could be an effective and convenient option.

After doing either of the above, you must take an extra precautionary measure by placing this container in an area that portrays the exact conditions as the container itself.

Consider doing a germination test before you decide to use these leftover seeds finally. Place 8-12 seeds in a wet paper towel and wrap them up. Place this in a sealed bag for a week and then count the sprouted seeds after.

The ratio of sprouted seeds to whole seeds will give you an idea as to the percentage of potent seeds.

Things to Avoid

grass seed going bad
  • Avoiding the label on your bag can be a stupid choice. Consider saving the expiry/testing date on the label in the form of a note. Otherwise, when you decide to plant those leftover seeds finally, you may be wasting time watering, nurturing, and feeding them fertilizers – only to find out they have been dead for a while.
  • Storage solutions that do not offer any kind of airflow. Airflow is a priority when you have already opened your bag once in the past and are now saving up leftovers. It helps to capture and churn out existing moisture that may have built-up on the seeds.
  • Never place these grass seed sacks in the middle of other bags or gardening equipment. It can build heat and lead to a humid atmosphere.
  • Don’t settle for cheap grass seeds and of low-quality. Look for information such as – less than 0.5% weeds, no more than 2% other crops, less than 2% filler material, no noxious weeds, etc. These grass seeds are purer and can last in storage for longer.
  • Avoid buying bags closer to their expiry date. Look for the freshest stock. This usually helps as not everyone lands up using all their grass seeds.


In short, the longer your seeds are stored, the lower the chances they will germinate. It would also be wise to check your seeds from time to time. You can then change the location if needed.

Don’t want to go through the hassle of grass seeds, grass seed planting, and then maintenance? Check out these grass-free garden ideas; they can save your money and give your backyard a unique look. 

On the other hand, if you are hellbent on a grassy lawn, these lawnmowers could save you plenty of work and effort in the future.

Did you enjoy the article? Also, check some related articles.

Leave a Comment