How Long Does Grass Seed Last?

Are you dreaming of a lusciously green lawn?

Scattering your lawn with grass seed at the right time is a great way to fill in patches and boost the overall greenery.

If you’ve bought grass seed out of season, there’s no need to panic. Storing it properly will help it last a long time. But if you’ve found a box of grass seed from ten years ago in your garden shed (that you bought with good intentions!), you may be wondering if it’s still okay to use.

Here’s everything you need to know about how long grass seed lasts, including does it expire, how to tell if it’s still good and tips on how to store it properly. 

Does Grass Seed Expire?

Grass seed is pretty resilient and can last for a long time. It won’t necessarily expire, but its germination rate will reduce the longer you have it for.

When you first buy your grass seed, you can expect an 80-90% germination rate of the seed. This means that at least 80% of your grass seed is likely to sprout once sowed. Every year, the germinate rate will gradually decrease. That’s why it’s better to sow your grass seed almost immediately after purchase. 

How Do I Know If My Grass Seed Is Still Good?

The best way to know if your grass is still good to use is to conduct a DIY germination test. 

Here’s what you need to do:

  1. Take a handful of seeds
  2. Place seeds in kitchen roll and spray with water
  3. Wrap seeds up and place in a clear container
  4. Leave on a sunny windowsill
  5. Spray the seeds with water when the paper towel gets dry

If, after two weeks, your seed hasn’t sprouted, it’s likely no good.

DIY Germination test

What Affects How Long Grass Seed Lasts?

The main thing that affects how long grass seed lasts is how well it’s been stored. In the proper conditions, grass seed can last up to five years. 

How Long Does Grass Seed Last in Storage?

Grass seed stored properly can last up to five years. However, with every year that passes, the viability of your grass seed will reduce by around 10%. 

For the best results, use your grass seed immediately or within the first three years of purchase.

How Do I Store Grass Seed Properly?

To help your grass seed last longer, storing it properly is important. For the best results, store your seed:

  • At room temperature – Anywhere around 15 degrees Celsius is ideal to avoid grass drying out.
  • Away from direct sunlight – Seeds left in the sunlight can quickly lose their viability, so it’s best to store them in a cupboard or somewhere dark, like the basement.
  • Somewhere dry – Grass seed left in humid conditions will absorb the moisture from the air, making it less likely to germinate.
  • In the original packaging – Keeping grass seed in its original packaging can help it retain its normal moisture levels.

Why Didn’t My Grass Seed Grow?

There are several reasons why your grass seed may not have sprouted the way you wanted it to. The most common reasons are:

  • Planted at the wrong time – Spring or Autumn is best.
  • Too hot/dry – Seeds without enough water can quickly die out.
  • Too wet – There’s a fine line between enough water and too much when it comes to grass seed (and grass in general!). Grass seed may not have survived if it was watered too much or the weather just wasn’t on your side. 
  • Too shady – Grass needs a lot of sunlight to survive. If the patch you tried to grow was too shady, it may not have stood a chance.
  • It wasn’t good to begin with – If the seed was too old or hadn’t been stored properly, it may have been doomed for failure from the get-go!

How Long Does Grass Seed Last Without Water Once it’s Been Sowed?

Without water, grass seed that’s just been sowed can last a few weeks, so there’s no need to panic if you’ve forgotten to water it.

However, grass seed that’s already sprouted will only last a few days without water. If the rain isn’t helping you out, it’s best to get out there with the hose as soon as you can.

How to Get the Best Results from Grass Seed

For the best results from your grass seed, make sure you:

  • Store it well
  • Use it within the first year of purchase
  • Sow at the right time
  • Look after it properly once sowed

If you do all these things, you should have a luscious lawn in no time!


Has your Grass Seed Already Expired?

We’ve all been there! 

If your grass seed didn’t pass the germination test, it may be best to chuck it out on the patio for the birds to enjoy. At least it won’t have completely gone to waste!

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