How long does grass seed last

You’ve looked over your yard and noticed it’s looking a bit bare. It’s the perfect time to make use of the old bag of grass seed to plant in your lawn. But then you think ‘ what if my grass seed has expired?’

If you’re now thinking ‘does grass seed expire?’, this article will help you find out if you could continue to use the old bag of seeds.

A small pile of grass seeds
A small portion of grass seeds

Can grass seed expire?

Let’s get the urgent question answered first. Yes, grass seeds can expire. All grass seed packages have expiration dates printed on them. They are also likely to degrade as time passes. It is usually best to dispose of grass seed that remains unutilized past its expiration date.

As the grass gets older, there’s less of a chance of seeds that can be planted successfully and develop. This means that you will have to use more seeds than you would normally for sufficient germination and adequate coverage.

Sometimes, even after hours of feeding, irrigating, or taking care of old grass seeds, they may result in no grass.

The shelf life of grass seed

Another question that is important to answer is ‘how quickly does grass seed expire?’

If stored properly, grass seed can be kept for as long as five to six years. It will lose approximately 10% of its viability every year if it is stored in an unopened bag. 

This means that 10% fewer seeds will germinate when they are planted and you’ll need more seeds as compared to the case of fresh seeds. If the seed has been stored for more than five years, its germination rate should be around 50%.

The 10% rule is an average rule of thumb. This number can change depending on what type of seed is used and how it was stored. For the best results, use fresh grass seed whenever you reseed your lawn.

How to shop for grass seed?

The type of grass that you buy, the brand that you buy from, and the storage conditions of grass seeds at the store also affect their shelf life. So here are a couple of tips on how to buy the best seed.

Which grass seed type should you buy?

A study from Oregon State University found that creeping bentgrass seeds have the longest life expectancy. Even after five years, the seeds should remain viable at 50%. After 3-5 years of storage, Kentucky bluegrass, tall Fescue, and Perennial Ryegrass should be at least 50% viable.

Fescue grass seed is another popular grass seed type that can last for up to three years. Keep in mind that the chances of germinating while in storage are lower so it is important to spread more grass seed over a larger area to ensure that some of it doesn’t sprout.

How to choose the right brand of grass seed?

It is smart to choose a trusted brand for your grass seed.

Cracked or broken seeds can accumulate moisture, which causes them to fail to germinate. The high-quality seed will contain fewer damaged seeds, which means that you can have more chances of having a lush green lawn.

High-quality seed can be expensive. However, it is not as difficult to get a good start with grass seed.

Many name-brand grass seeds contain fillers and mulches that aid in germinating the seed. We would recommend buying 100% seed unless you have a very small lawn.

What are other factors to consider when buying grass seed?

Since seed storage is very important you should ensure that the bag you buy at the store is not opened.

The smallest amount of moisture buildup can cause pathogens to infiltrate the inside of a bag and make the grass seed go bad. It won’t germinate, no matter how many times you water it.

Also, look at how the bags are placed on the shelves. To allow airflow around them, make sure they are placed upright.

Airflow is limited by stacking seeds on top of each other. The grass seeds could absorb moisture if they are kept like this for too long, which reduces their germination rate.

You can check the back of most bags of grass seed for a date. Always purchase the freshest grass seed.

Best way to store grass seed

How you store grass seeds has a huge impact on their shelf-life and that’s what the condition of your grass seed depends on most. Proper storage is a great way to not let your grass seed go bad.

Although many people would recommend an outdoor garage or shed for the storage of seeds, these locations aren’t recommended because of the extreme heat and humidity.

In order to properly store grass seed, it is recommended to put the sealed bag with grass seed in the coolest place you can find, such as the cellar or basement, insofar as they’re totally dry and temperatures remain between 40 and 55 degrees Fahrenheit.

Storage of grass seeds
Bags of grass seeds

Useful Grass Seed Storage Tips

The storage area must be dark and cool far from direct sunlight, and devoid of humidity. It is best to store it in a room that is air-conditioned.

In the ideal scenario, steps should be taken to make sure that the air temperature remains less than 60 degrees Fahrenheit, and that the relative humidity must not be less than 60 percent.

Even if the bag is not opened, make sure that there is adequate air circulation in the bag.

It’s a good method to store the seeds in mesh bags with air vents. In this way, air can get into the bags, which is beneficial for seeds. Also, the mesh stops insects from entering and protects the seeds from them.

To reduce moisture and fungi, place a baking soda container inside your grass seed bag.

As you can see, the principle is that you keep seeds warm. 

If you decide to store the seeds in storage space, you must be certain to keep rodents and insects out of the seeds. They could cause damage to the entire batch of seeds.

Why didn’t my grass seed grow?

Let’s suppose you have done everything right. You purchased quality seed, made sure that the bag’s date is up-to-date, and didn’t use grass seed from an improperly stored or opened bag.

Even if you have followed all the steps correctly you may still find that your grass isn’t growing as fast as you expected. This can be frustrating but it could just be a sign that something is wrong with your seeds. 

Cold Weather

Frost can hinder seed growth. For grass seed to germinate, soil temperature must reach at least 55° and temperature must remain at 60° or higher. 

You can’t plant your seed too early in spring. It will just sit on top of the soil and won’t sprout. Many seeds become damaged by the time the warm weather approaches and won’t germinate, making your new growth uneven and patchy.

 If it’s springtime and you feel it’s time for planting seeds, wait another 10 days. This will ensure that you don’t waste any grass seed.

Wet Weather

Germination occurs if there is enough water. However, too much can cause severe problems. 

To get the best results, you should plant grass seed after most of the spring rains have stopped. For best results, it’s better to make the soil moist by gently watering the seeded areas.

Not enough sunlight

To germinate, most grass varieties require at least 3 hours of sunlight per day. Low sunlight areas may be more suitable for grass growth if the area receives less than 3 hours of sunshine per day. 

Tips for Sowing Grass Seed

You must give grass seeds the best care to ensure they germinate. If you are determined to sow older seeds in order to see if they germinate, there are additional steps you can take.

Make sure to water your seeds at least twice a day and keep the soil moist. You should keep about an inch of soil moist to encourage germination. After that, water your soil once a day.

Once the grass grows to about three inches tall, you can mow the lawn as usual. You can resume your regular watering schedule after the lawn has been mowed.

It is important that your seeds do not dry out. Avoid covering them with straw, as it could contain unwanted weeds. We recommend that you cover them with a thin layer of topsoil. 

Sprouts of grass
Grass sprouts

How to check if grass seed is okay to plant?

Although you should always check the expiration date on the bag of grass seed to make sure the seeds are still good, the dates are not always exact. Sometimes expired grass seed can still be good enough to plant.

It is possible to detect the signs of grass seed going bad if there are not any visible signs.

If you are unsure whether to sow the old grass seed, here are some ways to find out if your grass seeds are okay.

Seed germination test

The seed germination test is a quick and easy method to determine the quality of grass seeds you’ve discarded because some will be good for a long time after expiration.

Step 1:

Take a paper towel and lightly wet it with water. Then put 5 to 6 seeds inside it.

Step 2:

Place the damp paper towel inside a plastic bag. The cover creates a greenhouse effect, trapping heat inside. To keep the paper towel moist, you can add water as necessary. But be careful not to add too much.

Step 3:

Then place it in a hot area. We suggest putting your towel over your radiator or clothes dryer.

Step 4:

The grass seeds should begin to sprout in the next 10 days. If only half of the seeds sprout, you can be sure that the seeds you plant will be viable for about 50% of the time. Plant twice the recommended amount of grass seeds each time you reseed your lawn.

Physical signs of grass seeds expiring

For the most part, when you look at seeds, you’ll see that there are rarely any obvious signs to indicate that they’ve expired.

However, sometimes it becomes apparent that you shouldn’t plant the seeds on your lawn. 

Take a look at your leftover seed, and examine them carefully to see if there are any indications of fungi or discoloration. Also, if the grass seeds are clumpy or damp, it means that you have not stored them properly.

If you spot any of them it is advised to get rid of the seeds and purchase a new bag of fresh seed. If you decide to continue using the grass seed, you’re likely to see patches of grass and less sprouting.

Grass growing on a lawn
A close-up of lawn grass


A great way to keep your seeds in good condition is to store grass seed properly.

If you have any leftover grass seed make sure to store it in a sealed container. Once sealed, place it in a dark, cool dry area with good airflow in the bag. If you do this, it will last for several years.

If you’re not sure whether your seed has gone bad or not, you can test it yourself by doing the seed germination test.

Make sure you follow the entire instruction on the bag since every type of grass has its own unique growth pattern.

Follow these suggestions, and we’re sure you’ll be thrilled with the chance of getting a beautiful lawn that will be the envy of your neighbors.

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