Does Grass Seed Go Bad: How Long Does Grass Seed Last?

You may have noticed a bald spot in your lawn or simply just want to create more lawn area, and in the back of your mind, you still remember having some grass seeds left over from the last time you seeded your lawn. The question we have here is, does grass seeds go bad, will these grass seeds still germinate and grow?

We have to keep in mind that grass seeds are living organisms that interact with the environment around them and that also have a limited shelf life. Depending on external factors and environmental and storage conditions, yes grass seeds do go bad is the answer to your question!

Although do not be discouraged as there are ways to expand their shelf life and those seeds you have been saving might just have been in favorable enough conditions to still grow healthy and lush. Just because the seeds are a bit “Off” also does not mean they will not grow at all they may just need a little more love and care!

Even the most looked after lawn, that is mowed, reeled, and fertilized regularly, needs good quality seeds.

Does Grass Seed Go Bad?

The short answer is: yes. Eventually, depending on conditions and storage environment and methods, all grass seeds go bad. But let’s have a further look at how and why grass seeds deteriorate over time. The expiration date on the package is for guidance only and seeds may be fertile even after the date.

Take into consideration that seeds are alive and need the appropriate surroundings to live in even if they are dormant. The germination rate of grass seeds decreases with age and an old seed bag might have disappointing results.

Factors That Affect Seed Viability

The quality of the grass seed also plays a role in its longevity along with the temperature, humidity, and storage container it is kept in. Some varieties of grass seeds last longer than others.

Keeping birds, insects and rodents away from your grass seeds is important to keep them safe.

Also, grass seeds need to be kept dry and in temperatures that are not too cold to cause freezing. Older seeds however do not want too much heat or humidity. As recommended by Oregon State University, seeds should be kept below 60 degrees F and at a relative humidity of 60% or less.

Ventilation is also important as most seeds can suffocate in a shed or area that is too densely stacked and not well ventilated.

Old grass seeds can still be used and may grow with extra care, fertilization and watering. You may need more seeds though as not every seed will germinate as with younger and fresher seeds.

Does Grass Seed Expire?

Grass seeds usually have an expiration date that is stamped on the packaging, which it should live up to if kept in the prescribed conditions. It is not guaranteed that the seeds will stay viable though.

There is no sure-fire method to know if grass seeds are expired or not and even the expiration date on the packaging is a guesstimate of how long they will last.

You can however look at the texture of the grass seeds if they are clumpy or not and also if there are any foul smells.

How Long Does Grass Seed Last?

We have found that according to most companies grass seeds are in their prime condition when they are less than one year old.

In fact, the question of how long can you store grass seed is not that simple. Although we have also noted that some grass seeds, such as rye grass have lived up to 5 years in the correct environment with proper storage, according to Scotts.

Most other grass seeds should be quite good for between two to three years on average. Once again all of this will depend on storage methods and conditions as well as the type of grass.

How Do You Know If Grass Seed is Still Good?

To determine the viability of grass seed, follow these steps:

Visual Inspection: Examine the grass seed closely for any discoloration or presence of fungi. If you notice any of these signs, the seed is no longer usable and should be discarded.

Smell Test: Give the grass seed a sniff. If it emits a musty or off odor, it’s time to dispose of the seeds.

Germination Test: Perform a germination test using a Styrofoam coffee cup and a paper towel. Place the paper towel in the cup, add about one inch of water, and sprinkle the grass seed on top of the damp paper towel. Put the cup in a warm, sunny location such as a window sill. Regularly check the seeds every few days and water if necessary. If the seeds sprout, they are still viable and can be used for planting.

Water Test: Take a bowl of water and place the grass seeds in it. Allow them to sit in the water for approximately 15 minutes. If the seeds sink to the bottom, they are still viable for germination. On the other hand, if they float, it is likely that they will not sprout and should not be used to plant grass seeds.

How Long Will Grass Seed Last in the Ground?

The lifespan of grass seed in the ground can vary depending on various factors, such as the type of grass, environmental conditions, and seed quality. In general, most grass seeds can remain viable (able to germinate) in the ground for around 2 to 3 years. However, some grass species have seeds that can stay viable for longer periods, while others may lose their viability more quickly.

Proper storage of grass seed is crucial to maintaining its viability. If kept in a cool, dry, and dark place, the seeds are more likely to retain their viability for a longer time. Conversely, if exposed to heat, moisture, or light, the seeds may lose viability more rapidly.

Keep in mind that as time goes by, the germination rate of the grass seed will decrease. So, while the seeds may still be viable after a few years, the percentage of seeds that will actually germinate successfully may be lower.

If you’re planning to use grass seed, it’s always best to check the expiration date on the seed package and follow the guidelines provided by the manufacturer to ensure the best germination results. If you have older grass seed, performing a germination test before sowing it extensively can help you determine its viability and adjust the seeding rate accordingly.

How to Store Grass Seed Correctly?

Moisture

Seeds should be kept dry and prevented from absorbing too much moisture that can cause fungal issues and decrease their viability. General humidity for storage should not exceed 60%. 

Containers

Containers should be suitable for the seed type and be kept well sealed to keep internal moisture levels and not introduce extra moisture from the outside.

Ventilation

Keep your grass seeds in a well ventilated area that is not densely stacked as grass seeds need constant airflow to stay fresh and to prevent mold. Grass seeds go bad quickly in enclosed, damp, clumpy storage places.

Temperature

Most grass seeds need temperatures that are not too hot and that will also not be cold enough to cause freezing. Make sure to keep grass seeds in a cool area that will keep their temperature reasonably constant. As a best practice, store your grass seeds below 60 °F (source). 

Storing Left-over Grass Seeds

You may not use an entire bag of seeds all at once, and here we recommend that you use the right type of packaging to store grass seeds that left over. 

A cloth sack or a burlap bag should do the trick as they both allow good airflow.

To limit moisture some say that placing a container with baking soda inside the bag can eliminate some of the extra moisture.

What to Do With Old Grass Seed?

If you possess expired grass seeds that is no longer viable, consider the following options:

• Composting: If you have a compost pile, adding the old grass seed to it is a suitable way to dispose of it.
• Throwing it away: Discard any grass seed that shows signs of discoloration, or fungi growth, or emits a musty or off smell, as it is no longer suitable for use.
• Over-seeding or small lawn repairs: If you have leftover seed from the previous season and wish to save it for over-seeding or minor lawn repairs in the spring, you can still use the old grass seed. However, be aware that the germination rate might be lower compared to fresh turfgrass seeds.
• Donating it: If the grass seed remains viable, consider donating it to a community garden or offering it to a neighbor in need.
• Proper storage: To prolong the shelf life of the old grass seed, store it appropriately in a cool and dry location.
• Perform a germination test: If you’re uncertain about the viability of the grass seed, conduct a germination test. Place the seeds on a wet paper towel or in a bowl of water and observe if they sprout.

Conclusion

As we can deduce the three enemies causing grass seed to go bad faster are moisture, air, and temperature. By keeping grass seeds reasonably dry, at a moderate and constant temperature with good ventilation, they should last quite long and therefore we can increase the shelf life of grass seed extensively.

Make sure to also keep your seeds in a sealed container and environment where pests such as rodents and insects cannot intrude. All grass seeds do go bad eventually, you can use the expiry date on the packaging as a guideline.

By following these guidelines we have given you should be able to keep your grass seeds fresh for a longer period as well as be able to calculate their shelf life correctly.

Also, pay attention to birds and pests when grass seeds are exposed. Fortunately, there are ways to keep birds away from eating grass seed.

There may come a point when using the best quality grass seeds is not enough and invasive species attack your precious lawn. Then, there is no other way but to look into ways to fight back either using chemicals or other, more gentle methods. Read more about weed control here. 

Getting rid of trees that may litter the lawn could be an option too, but pay attention to the increased risks.