Does Grass Seed Go Bad?

Maybe you’ve had this experience. You go to the big box store and stare at several different kinds of grass seed. The more you look, the more confused you get. How do you know which type to buy when there’s no one to ask? When you do buy, you might buy too much grass seed, and now you are wondering if it’s going to last until next season. Does grass seed go bad? The answer is that it can … the shelf life of grass seed depends on many factors.

Here are some tips for choosing the perfect grass seed for your needs and storing the left-overs properly for next season.

I’ll also tell you how to make sure the grass seed you’re buying hasn’t gone bad.

Choosing the Right Grass Seed

Before we talk about how to store grass seed so it doesn’t go bad, let’s dive into a few of the most common questions homeowners have about buying grass seed.

Hopefully this information will help guide you toward making the right decision.

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What Type of Seed Should I Buy?

A lot of factors go into choosing the right grass seed.

First of all, you will need to consider the conditions of the area.

That’s a fancy way of saying: what is your lawn like?

For instance, do you live on a shady lot? Do you have heavy clay soil, or is your lawn mostly sand?

The conditions of your lawn will dictate what type of seed will thrive and perform best in your lawn. It may be a different type of grass than what your neighbor across the street has.

A good rule of thumb, however, is that buying an all-purpose grass seed that’s geared toward your region (cool season grassses if you’re in the northern half of the US, warm season grasses in the southern half).

Blends of seed offer a little bit of everything, and typically some of the grass types in the mix will do better in shady areas, others will thrive in full sun, and you’ll have good coverage across your entire lawn.

After seeding all of your space with the all-purpose seed, you can address problem areas later. 

Try These Guides

If you’d like to dig in more, I have guides for choosing grass for the following types of lawns:

• Grass for Shady Lawns
• Choosing Grass for Clay Soil
• Grass for Sandy Soil

Perennial Ryegrass and Kentucky Bluegrass are popular all-purpose choices. This popularity is partially because they are hardy in zones 3 – 9. They also have a longer shelf-life than some other grasses, so if you’re shopping at the box store you’re more likely to get seed that will germinate well.

These two types may not be right for all situations, but they are standard all-purpose grasses that grow just about anywhere.

What Brand Should I Choose?

Choosing a trusted brand when buying your grass seed is also smart.

Cracked and broken seeds accumulate moisture and ultimately fail to germinate. Quality grass seed will have fewer damaged seeds which means you get a lush, green lawn faster with less reseeding. 

Scotts, Jonathan Green, and Pennington are three quality brands consumers have grown to trust over the years, and you can buy seed from these brands online on Amazon (Amazon links: Scotts, Jonathan Green, Pennington), or locally at your hardware store or local big box retailer.

I use Jonathan Green seed which I buy directly from the manufacturer. I find this gets me the freshest, best-quality seed. This one is my go-to and I highly recommend it.

Grass seed is expensive, and the price you pay for quality seed is worth it because it doesn’t take as much to get a good start.

With that said, a lot of name-brand grass seeds are primarily fillers and mulch that help the grass seed germinate. Unless you’re doing a small section of lawn, I recommend getting grass seed that’s 100% seed.

There are other reliable brands, but if you’re shopping for grass seed for the first time, you will probably have good results with Scotts and Pennington, or fantastic results with Jonathan Green.

These three are consistently praised for producing quality turf, and Black Beauty Ultra from Jonathan Green is what I use in my lawn.

Other Factors to Consider When Buying Grass Seed?

Because moisture is detrimental to your seed’s productivity, make sure the bag you choose at the store has not been opened.

Also check the bag for tears before you take it home.

Even the slightest bit of moisture infiltrating the interior of a bag of grass seed can create pathogens that break down and rot the seed. This will make it go bad, and it won’t germinate no matter how much you water it. 

Also, look at the way the bags are stored on the shelf.

Make sure they are stacked upright with a little space between each to allow airflow to circulate around them.

Packages of seeds that are stacked on top of one another limit airflow. If they are stored this way too long, the seed inside could start to collect moisture, reducing germination rate.

Oh, and you can check the back of the bag. Most bags of grass seed have a date printed on it somewhere, so if you have a shelf full of seed you might find a few bags that have been sitting there for years, and a few that were bagged a month ago.

Always buy the freshest one.

The Shelf-Life of Grass Seed

As I just mentioned … when you are buying grass seed at the store, you need to check the date on the bag to make sure it isn’t a decade old.

But if you are wondering how long grass seed will last at home after opening your bag of seed, the answer depends upon how you store it.

Grass seed is a living organism that becomes activated by sunlight and moisture.

Sealing open bags of seed using a heavy-duty tape will allow you to store it for a few seasons without compromising the germination rate too severely.

If you have a heavy duty freezer bag to keep moisture out that’s great, but store that bag somewhere cool where heat, light, and critters can’t get to it.

How Quickly Does Grass Seed Go Bad?

On average, each year grass seed sits in an unopened bag,  it experiences a 10% reduction in germination rate.

This means 10% fewer seeds will sprout when planted, causing you to use more seed (and spend more money) than if the seed was fresh.

Because reduction in germination occurs in unopened bags, proper storage of opened bags is even more critical.

Even if you store your opened grass seed perfectly, you can still expect a reduction in germination rate from year to year.

How To Store Grass Seed

A quality, hardy seed can last for up to 3 – 5 years if stored in a dark, cool place free of humidity.

I recommend that you keep your seed in its original bag, and seal that bag shut with a heavy-duty tape.

Do not stack packages on top of one another and position bags to allow air flow around them, reducing the chance for moisture to accumulate.

Is My Old Grass Seed Still Good?

Before purchasing new seed, you can test the seeds you have by following these simple steps:

1. Put a damp paper towel in a cup.
2. Add about 1” of water in the bottom.
3. Sprinkle the grass seed on the paper towel.
4. Put a plastic bag over the top of the cup to create the green-house effect.
5. Add water when needed to keep the paper towel moist.
6. Put the cup in a dry, sunny spot.

The seeds should begin to germinate in 10 – 14 days (or less).

If they don’t, or if only a few sprout, you need to purchase some fresh seed.

Why Didn’t My Grass Seed Grow?

Let’s say you’ve done everything right:

• Purchased quality seed
• Made sure the date on the bag was recent
• Didn’t get an opened bag that was stored improperly
• Followed the planting directions

However, your seed failed to thrive. That’s frustrating, but there might not be anything wrong with your seed!

Here are some common reasons you didn’t get the lush new growth you were expecting.

Cold Weather

Cold weather will hinder seed growth. For grass seed to germinate, the soil temperature must be at least 55 degrees, and the air temperature should be consistently at 60 degrees or higher. If you plant your seed too early in the spring, it will sit on top of the soil and not germinate. By the time the weather warms up, many of the seeds are damaged and won’t sprout, leaving your new growth sparse and patchy. I always say that when you think it’s time to spread seed in the spring … wait 10 days to be sure you don’t waste your grass seed.

Wet Weather

While seed needs water to germinate, too much of a good thing will severely hinder growth. For best results, plant grass seed after the majority of the spring downpours have ended. Gently water the seeded areas the right way for best results.

Lack of Sunlight

Most varieties of grass require at least 3 hours of sunlight daily to germinate. Areas receiving less than this amount might be more conducive to low sunlight ground covers if grass refuses to grow. You could also try to lay sod yourself with a grass type that thrives in shade.

Does Grass Seed Go Bad? It Can, So Be Careful

The possibility of growing a beautiful, green lawn increases significantly when you pay attention to a few details.

Choosing a quality, all-purpose grass seed and spending a little more money is a smart decision since you will need less to produce the results you want. 

As for that leftover seed, make sure you seal the bag properly. Once sealed, store it in a cool, dark, and dry place with good airflow around the bag. Do this and it should be good for a couple of years.

Just keep in mind, it will lose some effectiveness each year, meaning with every year that passes, you’ll have to spread that seed a little heavier.

If you are not sure if your seed is still good, test it indoors using the method I outlined above. 

Finally, be sure to follow all directions on the bag because every variety of grass grows differently.

Keep all of these tips in mind and I like your chances of having a gorgeous, green lawn that is the envy of the neighborhood.