Does Grass Seed Expire or Go Bad?

When it comes time to create or renew a lush, thick carpet of grass in your backyard, there are multiple strategies for which to do it. One of the most common and oldest known methods is to spread grass seed, water it and feed it, and wait for it to grow.

You might have an old bag of grass seed in your shed or garage, left over or unused from the year or two before. This begs the question – does grass seed expire or go bad? That’s a question many homeowners have when they’re stocking up on this important gardening supply.

In this blog post we will explore the topic of whether grass seed goes bad or expires and provide some tips on how to get the most out of your lawn seeding efforts. Whether you have annual ryegrass, perennial ryegrass, Tall fescue, Fine fescue, Kentucky bluegrass, or Bermudagrass, knowing how and when to restock on your grass seed can save you money and headaches down the road.

Note that the lifespan of grass seed can vary depending on the type of seed, so always read the package labeling carefully! Read on to learn more about how to store grass seed and how long it lasts.

How long can you store grass seed?

The rule of thumb when it comes to storing grass seed is that it can be stored approximately 2 to 3 years and still be viable enough to use. However, grass seed that is less than 1 year old is still the best. This is because seed tends to lose about 10% or more of its efficacy per year.

Theoretically, this means that there should still be some viable seeds in bags up to ten years old, but this is most likely not the case. Firstly, grass seed that you buy and immediately plant will not germinate at 100% – typically its germination rate is about 80-90%. Also, after a few years it is simply cheaper to get a new bag of seed than to try and plant, water, and feed grass seed that won’t grow.

Different species of grass have different shelf lives, however, so you should always read the expiration label on the bag. For example, seeds for Rye Grass can stay viable for up to 5 years, whereas some common lawn grasses like Bermuda Grass and Fescue have comparatively short viability windows. A good rule is to not let it get more than 1 year older than the expiration date.

How will I know if my seed has expired?

Firstly, check the expiration date. Every bag of grass seed has one, and this will let you know whether or not your grass seed is past its usefulness. You can add about a year to this date and still get some use out of your grass seed, but this is only if it’s been stored in perfect conditions. Also, if your grass seed is past the expiry date, then you will need to over-seed your lawn, because the seed germination rate will be considerably lower and you don’t want a patchy or thin lawn.

However, there are no clear indicators that expired grass seed is not viable, but you should give it a look through anyways. Firstly, examine the seed carefully for any patches of fungus or discoloration. You can also take a whiff to determine whether your seed contains any strange or foul odors, and look for clumpy, moist regions.

If any of these factors are present, it is usually preferred to start with a new seed. If no, try sowing the seeds with the knowledge that they may or may not germinate, based on their age.

Is My Old Grass Seed Still Good?

One way to tell if your grass seed is still viable and able to be germinated is a DIY home test. Within a sealed plastic bag, place ten seeds on a moist paper towel, and then place the bag in a warm location for 10 days to see if any seeds germinate. The seed’s viability rate is determined by the amount of seeds that sprout after germination.

If fewer than five of the seeds sprout, the percentage survival is less than 50 percent. If your germination rate is 50 percent viable, you should plant double the recommended amount. Anything below this, it is probably more cost effective to buy a new bag.

How to store grass seed correctly?

Your grass seed will eventually not be viable, but there are ways you can slow down that process, and keep your grass seed healthy and able to sprout for longer.


It is best to store grass seed in a cool, dry location. The back of a garage or garden shed works well, as long as it is sealed and not damp. Moisture can also cause the seeds to sprout while still in the bag, which is also not what you want.

Moisture can come from many sources, like rainfall or watering your lawn, so the last thing you want is moldy seed! The drier, the better when it comes to grass seed.


One good idea for storing grass seed would be to place them inside a resealable bag and then place that bag inside an airtight container. This way, you can get multiple uses from the same plastic bag before moving onto a new one. Since it is susceptible to fungi growth and insects, you should prevent these factors by using airtight containers that are moisture proof.

If you want to plant the seed in the following season, bulk storage bags will suffice. The reason for this is that plastic bags, with perforations, allow trace amounts of humidity to enter over time, which inhibits germination.


Storage bags should be stored in a dry place with good ventilation to avoid moisture’s detrimental impact.


It’s also wise to avoid storing grass seed in direct sunlight or near heaters or other appliances since this may increase the risk of mold growth. Keep the temperature of the shed or garage mildly cool but not too cold; however, it is most important to at least keep the temperature from getting too warm.

Storing left-over grass seeds

If you’re keeping left-over seeds in a permeable container, like burlap, make sure there’s an opened box of baking soda nearby to keep moisture down. Make sure to date and label any remaining seeds as well, and be sure to always examine the seeds for signs of excessive dampness or mildew before using them.

Storage Conditions

Make sure your grass seed is stored in an area that animals or insects cannot get to it. Rodents and other vermin can be a problem since they consume the seed but not its husk, which may lead an uneducated eye to believe that the container is still full.

Why Didn’t My Grass Seed Grow?

There could be a situation where you plant lots of grass seed that you thought was viable and it didn’t grow. Why could that be?

Even if your grass seeds are completely healthy and able to sprout, there could be environmental conditions that cause them to not grow for whatever reason, like cold, wet, and dark weather.

Cold Weather

If the ground is too cold, the seeds will not germinate and therefore not sprout or grow. Also, the grass seed could possibly die if it is exposed to extreme cold temperatures.  

However, you should also avoid trying to seed your lawn when it’s very hot out. When extreme heat conditions are present, seeds may not germinate or grow because the ground temperature may be too high. This will also cause your grass seed to die.

For this reason, most people tend to aim for middle or end of spring, depending on the temperature, for a good time to plant grass seed. If you live in more tropical regions, or in the southern United States, the early springtime would be best.

Wet Weather

It is important for growing seeds and grass to get a fair amount of water. You should water your seed twice a day for the first few days after planting to keep the top inch of soil wet until it germinates, and water every day after the seeds germinate. Begin mowing when grass reaches approximately 3 inches in height, and after you’ve mowed your new grass once or twice, you may resume your usual watering schedule.

However, too much water could wash away the seeds before they have a chance to get planted and stuck into the soil. If you see multiple days of heavy rain on the forecast, don’t try to plant your grass seed during that time. It is always better to aim for a dry patch of days and water the seedlings yourself than to watch them wash away in the rain.

Lack of Sunlight

Grass, like all plants and living things, needs sunlight to grow. If it is too dark most of the time(again, another reason to not plant grass seed in the winter) or if it is overcast and no sun is forecasted for multiple days, do not plant your new grass seed during this time.

Final Thoughts

There you have it. Grass seed does expire, and it will go bad over time. The older the grass seed is, the lower its germination rate will be. This is why we recommend to use grass seed within one year of purchase, or within 2 to 3 years if it is stored in proper conditions.

Follow these tips to store and use your grass seed correctly, and increase your chances of a successful lawn. We hope you find this information helpful and informative, and wish you a happy seeding and growing season!

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Written by Linda Chan
Linda Chan is a passionate gardener and writer with a background in horticulture and landscape design. She has over 10 years of experience working in the lawn care industry and has a deep understanding of the science and art of keeping a lawn healthy and beautiful.