How Long Does Grass Seed Last?

Most likely, you won’t use the whole bag of grass seed unless you’re reseeding your whole yard. There will be some left over if you’re only reseeding a few spots. It’s not cheap to buy grass seed, and it usually comes in large amounts, so you’ll have plenty for later use. But does grass seed go bad?

If grass seed goes bad, how can you tell if it’s been turned, and how to store it so that it stays in good shape for as long as possible?

Key Takeaways

  • Grass seed has different shelf lives based on the type, quality, storage conditions, and dates when it expires. For the best results, you should use fresh grass seed.
  • Keeping grass seeds alive over time requires the right way to store them. People who own their own homes should keep grass seeds in cool, dry places that are out of direct sunlight and moisture.
  • Low germination rates can happen when grass seed is old or not viable, which can make it hard to establish a yard and hurt plant health. Before planting, germination tests can help you figure out if the seeds will grow or not.

How Long Does Grass Seed Last

Does Grass Seed Go Bad?

Of course grass seed goes bad, but not in the same way that a fruit or veggie does when it rots. Grass seed just stops growing as it gets older. The rate of sprouting per unit of seed goes down, so you need to spread out more seed to cover the area.

How Old Is Too Old?

Grass seed can last for two to three years if it is kept in a cool, dry place. However, it might not grow as well as new seed. As seeds get older, fewer of them will be able to sprout. This means you have to use more seeds than usual to cover the area properly.

You can test older seeds by putting a paper towel in a Styrofoam coffee cup and adding an inch of water. Then, sprinkle grass seed on top of the paper toweling and placing the cup in a warm, sunny window. Check on it every few days and water it if it needs it so it doesn’t dry out. To make a small greenhouse, put a plastic bag on top of the cup. After 10 to 14 days, the seed should start to grow in the cup.

Factors That Affect Grass Seed Longevity

If you don’t keep your seed in a scientifically verified seed bank, it will go bad over time. Some of the things that cause grass seed to go bad faster can be avoided, but some of them can’t.

Time is the most important thing that affects your grass seed. Grass seed usually lasts between two and three years before it starts to sprout less quickly. The grass seed’s useful life will be shortened by heat, light, moisture, and wind.

To make your grass seed last longer, don’t store it where it is warm, bright, wet, or open.

Signs Your Grass Seed Is Expired

If you need to re-seed an area with old grass seed but aren’t sure if it will still grow, try these tests:

  • Put some grass seeds in a glass or bowl of water and watch how many float. This is called the “float test.” Most likely, your seed is good if more than 80% of them float.
  • Do a germination test. This is the most accurate way for the normal gardener, but it takes a lot of time. Get 100 seeds and put them on a paper plate with wet soil on top of it. Place the plate somewhere sunny and wrap it in plastic wrap. Every day or two, use a spray bottle to keep the dirt wet. Count how many green sprouts you have after a week. If you get 80 or more, your grass is still alive. A paper towel and water on a window sill will do the same thing, but it will be less controllable. You have to count the seeds because the ones that didn’t grow will be hidden in the ground and you won’t be able to see them.
  • Checking out physically: Pay close attention to the seed. Does it look and feel light? Does it have a uniform color? Does it smell clean and not musty? Seeds that are still alive will look hard and whole, and they will weigh more than seeds that are no longer alive.

How To Correctly Store Grass Seed

The most important thing you can do to store grass seed correctly is to make sure the bag is properly sealed again. Use more than one chip clip or office clip. In the event that you have an extra fridge in the garage or basement, put the seeds in the veggie crisper drawer. (The fridge is a great place to keep seeds for a long time.) If you don’t have a fridge, an empty covered cooler or a resealable storage bag is the next best thing to keep grass seed in. This is especially true if you live in a cooler area.

The Shelf Life Of Grass Seed

To figure out how long grass seed will last, you need to know how viable the seeds are.

Understanding Seed Viability

The power of a seed to sprout and grow into a healthy plant is called its viability. An alive grass seed has all the important parts it needs to grow, like embryos, endosperms, and energy stores that are still whole.

How long grass seeds stay alive depends on things like the type of grass, how it is stored, and its general quality. For example, if the right steps are taken to store perennial ryegrass seeds, they may last longer than Kentucky bluegrass seeds.

Additionally, better grass seeds tend to stay alive longer than their inferior peers.

Why It’s Not A Good Idea To Use Old Seeds

If you try to grow a new lawn using old grass seed, you might not get good results. It’s not a good idea because the seed loses its viability over time, making it less likely to sprout. As a result, you may end up with bald spots and thin patches in your lawn.

Using old grass seed could also mean using lower-quality seeds that have been stored for too long without being inspected for the right environmental conditions.

Buying new grass seed will definitely give you better results because it has higher germination rates, which means it will grow as much as possible and give you the lush greens you want.


Is It Ok To Use Really Old Grass Seed?

You can use really old grass seed, but after two or three years, there will be a lot fewer seeds that will still grow. This means that you will still need to use more grass seed to cover a field, even if you store it in a cool, dry place.

How Long Will A Bag Of Unopened Grass Seed Last Before It Goes Bad?

Two to three years after being stored in a cool, dry place, grass seed that has not been opened will have a noticeable drop in the percentage of seeds that will grow.

How Long Will A Bag Of Opened Grass Seed Last Before It Goes Bad?

If you store grass seed in a cool, dry place and make sure the bag is properly sealed, it will last for two to three years before the number of seeds that grow will start to drop.