Does Grass Seed Expire?

Although seeds can survive for many years in the correct storage conditions, some varieties can only last a few years in storage.

So before you use that old bag of grass seed, here is everything you need to know about storage, shelf life, and how you can check if the grass seed you have to ensure they are still suitable for use.

Table of Contents

Shelf Life

Grass seeds can expire but may still last up to 5 years if stored in a cool and dry space. But as a rule of thumb, it is best to use them within 2 to 3 years of purchase.

This is because, with each passing year, the germination rate will lessen by nearly 10 to 20 percent, depending on how it was stored.

Therefore, it is best to use grass seeds while they are still fresh or within the first two years of purchase.

Storage

An unopened bag of grass seeds, kept in an ideal storage condition,  can last up to 5 years. In comparison, an opened bag can last up to 18 months. 

According to the Seed Lab of Oregon State University, grass seeds that grow in hardiness zones 3 to 9 can last up to 5 years if kept in the best storage conditions. Common grass varieties, on the other hand, can last up to 3 years in storage.

Storing Unplanted Grass Seeds

  1. If you have an unopened bag of grass seeds, keep them in their original bag and store them in a rodent-proof container.
  2. For unplanted seeds, check the seeds if they are clean and dry, pot the grass seeds into a rodent-proof plastic container, and close it with a lid.
  3. Label the container with the date, brand, grass type, and seed testing date, which is the date the seed was tested for its germination rate. This information can be found in the original bag.
  4. Store the container in a dark, cool, and dry area, preferably in a dry basement with a temperature above freezing but below 60 to 70 degrees Fahrenheit and relative humidity below 60 percent.
  5. Check the stored seeds periodically for rodent damage and moisture.

Physical Signs of Expired Grass Seed

Sometimes, even if you do your best to store the grass seeds in a manner that will preserve them, they are still likely to expire over time. While usually, you’d want to check the expiry dates on the bag to see if they are still okay, the dates are not always accurate.

More often than not, these dates are just rough estimates, and the shelf life will still depend on the quality of the seeds and how well they were stored.

How do you know if grass seeds are still good?

Checking for these signs of expiration:

  • Signs of discoloration and fungi.
  • Clumpy and damp areas.

If you see any of these signs, it is recommended that buy a fresh seed packet.

But if you insist on using the seeds, then get ready for a patchy lawn due to the lower rate of seed germination.

3 Steps to Check if Grass Seeds are Still Good

Before buying a fresh batch of grass seeds, it is advisable to check if the old ones are still good to use.

Step 1: Damp it

Put a damp paper towel inside a cup and add a bit of water.

Step 2. Sprinkle It

Sprinkle the seeds carefully on the paper towel and put a plastic cover to create a greenhouse effect and trap in heat. Add water as needed to keep the paper towel moist, but avoid overdoing it.

Step 3: Wait for it

Put the cup in a dry and sunny spot and wait for 10 to 14 days or less to germinate.

If you notice no sprouting or germination after the 14-day period, then you should consider buying a new bag of grass seeds. 

Grass Seed Storage Tips

  • Always store grass seeds in a dark and cool location, meaning it should be away from direct sunlight and free of humidity, preferably in the basement with air-conditioning.
  • Ensure adequate airflow circulation even for unopened bags.
  • You can store grass seeds in a breathable bag with mesh or air vents to prevent insects from entering while allowing optimal airflow.
  • Burlaps are also ideal containers to prevent mold growth while still allowing air circulation.
  • Keep the bags separate from each other to minimize moisture buildup.
  • Put baking soda in a container and keep it inside the seed bag to reduce moisture and fungi buildup.
  • If you will not utilize the entire bag of grass seeds, then make sure you store the unused seeds properly in a mesh bag, burlap sack, or a rodent-free plastic container.
  • Remember that if you want to use old grass seeds that have been stored for more than 3 years, you have to sow more heavily for better results. 

Tips for Sowing Old Grass Seeds

Fresher seeds have a better chance of germination and sprouting than older grass seeds, however, if you want to use old grass seeds, here are some tips to remember:

  • Make sure you water the seeds twice a day and keep the top of the soil moist.
  • You have to keep an inch of the soil moist until germination starts.
  • After germination, water the soil only once a day.
  • When the grass is starting to grow to about 3 inches, you can begin to mow the lawn, as you would usually, and resume the watering schedule.
  • Ensure the seeds do not dry out, and try not to cover them with straw because they may contain unwanted weeds and seeds.
  • Cover the seeds with a layer of thin topsoil.

Reasons Why Grass Seeds Might Not Grow

Even after you follow all the steps and tips, you might still see that the grass is not growing as well as you expect it to. If you are a hundred percent sure that there is nothing wrong with the seeds, consider these other reasons that prevent grass from growing.

Cold Weather

Cold weather can hinder the growth process of grass seeds. So in order for them to grow, the soil temperature must be at least 55 degrees Fahrenheit, while the air temperature should be 60 degrees Fahrenheit or higher.

You should also take into consideration the season when you are planting the seeds. For instance, if you plant them too early in Spring, they will not germinate and by the time it gets warmer, several seeds are already damaged and might not sprout.

As a result, you’ll get patchy and sparse growth. So the ideal time to plant the seeds during Springtime is when it gets a bit more warmer.

Lack of Sunlight

The lack of sunlight can also be a problem when growing grass seeds. Sunlight is essential for any vegetation and all life forms to flourish, and most types of grass need at least 3 hours of daylight every day to germinate.

Areas that receive less than 3 hours will work best with grass covers that need low sunlight if ordinary grass refuses to grow.

You can also try to grow another grass type yourself to see which one thrives best in that area. 

Wet Weather

Water is also essential for growing plants and vegetation and also for seeds to germinate, however, too much water can be problematic too.

Seeds that get more water than needed can hinder their growth. Therefore, it is recommended that you plant the seeds only after the end of spring showers.

For best results, water the seeded regions in the right manner.

Frequently Asked Questions

Do expired seeds still grow?

Yes, expired seeds can still grow into healthy lawns as fresh grass seeds. However, you first need to check the germination success by following the three simple steps. First is to put the seeds in a damp paper towel, place it in a dry and sunny spot and wait for 14 days to germinate.

Can you freeze grass seeds?

You can freeze grass seeds, but for a short period of time only. Freezing grass seed will not affect its viability and will remain idle during freezing temperatures, however, you should only freeze them once or twice for a short period of time to not affect its quality.

When is it best to fertilize cool season grass?

During the late summer and early autumn, you should apply most of the liquid fertilizer to cool-season grasses. As a result, the turf recovers faster, shoots are more dense, and the turf is better prepared for winter without experiencing a growth surge.

Summary

Grass seeds do expire, but whether grass seeds go bad depends on the way you store them. 

To use grass seeds beyond their expiration date, keep them in a cool and dry storage space, but you should remember that the longer the seeds are stored, the lesser the germination rate.

Grass seeds that are stored in a sealed, rodent-free container and kept in the fridge usually lasts longer, but since this way of storing seeds isn’t practical for most, you can just keep them in your basement or the coolest and driest room in your house for up to five years.