The Ins and Outs of Fertilizer Shelf Life: Does Fertilizer Go Bad?


Are you wanting to know whether you can use that old packet of fertilizer you just found on the back of the shelf?

The answer is probably yes!

Fertilizer has a pretty impressive shelf life but it does depend on the kind of fertilizer and how it has been stored.

Keep reading to find out everything you need to know about how long you can keep fertilizer happy for many years.

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Key Points

  • Fertilizer shelf life is all about correct storage. If stored correctly, it shouldn’t go bad.
  • Liquid fertilizer is sensitive to temperature change and ideally needs to be kept between 50 and 80˚ Most liquid fertilizers last around 10 years if stored correctly.
  • Granular fertilizer is sensitive to humidity but if stored in a cool, dry place, should last indefinitely.

Does Fertilizer Go Bad?

Yes.

Fertilizer does go bad eventually, but it actually takes a lot longer than you might think. Properly stored fertilizer can last many years before it needs to be disposed of and replaced.

person using fertilizer

It also depends on the kind of fertilizer you have. Liquid fertilizer typically doesn’t last as long as granular fertilizer.

Some fertilizers will have an expiry date on the packaging but this isn’t necessarily reliable. If the fertilizer has been exposed to temperature changes then it might already have degraded before its official expiry date.

But what exactly do we mean when we say bad?

Bad means different things depending on the kind of fertilizer. Granular fertilizer can last a really long time, indefinitely even (if stored correctly), but if it’s exposed to moisture then it could start to harbor mold and degrade.

Liquid fertilizer can experience some crystallization when exposed to fluctuating temperatures which can degrade the quality of the nutrients it contains. This could make it a weaker solution in terms of how helpful it is for your garden, or it could upset the balance of nutrients and actually do more harm than good.

How to Store Fertilizer Correctly

As you might have guessed already, how long your fertilizer lasts basically comes down to how you store it.

Maintaining a constant temperature is the most important factor.

Fertilizer doesn’t like really high temperatures, or for that matter, really low temperatures. In fact, it really shouldn’t freeze.  So you should choose the location in your house or garage that maintains the most constant temperature all year round, ideally between 50 and 80˚F.

Humidity is also important for granulated fertilizer.

Keep your granulated fertilizer in a sealed container somewhere where it won’t be exposed to dampness.

person in yellow gloves holding granual fertilizer

How Long Does fertilizer Last if Stored Correctly?

Assuming that the old bag you found in your garage hasn’t been exposed to extremes of temperatures or dampness, how long is it good for?

  • Granular fertilizer can be stored indefinitely. Crazy, right?
  • Liquid mineral fertilizer can be stored for up to 10 years.
  • Liquid organic fertilizer varies depending on the ingredients but is likely a little less than 10 years.
  • Any fertilizer that includes herbicides will last even less time. While the fertilizer itself might be ok, the herbicide component will lose strength.

What to do if Your Fertilizer Has Gone Bad?

Fertilizer needs to be disposed of carefully. It can’t just be tipped down the drain as it could be harmful to water supplies and the local environment.

Your best option for disposing of organic fertilizer is to add it to your compost pile. This will allow it to break down and be suitably diluted before it gets added to your garden. It may even boost the nutrient composition of your compost.

Don’t have a compost yet? It’s never too late! All you need to get started is a kitchen compost bin for collecting food waste and keeping your kitchen odor-free, and an outdoor compost heap or tumbler if you’re keen to minimize the labor involved.

If your fertilizer is composed of any synthetic ingredients or herbicides, it’s safest to dispose of it according to the instructions on the back of the packet.

If you’re looking to learn more about fertilizer use and the different types, I have a couple more articles that you might find helpful on how often to fertilize and the difference between granular and liquid fertilizer.

granual lawn fertilizer

Summary

As you can see, this is a good-news article! It’s very likely that packet of old fertilizer is perfectly fine to use. But you can always up your game and be careful about future storage to ensure that any more fertilizer you purchase will also not go bad.

I hope this was useful. Feel free to hit me up with any questions below if there is something I missed!

Andy Gibson

My name's Gibson. Andy Gibson. I like to think of myself as the Bond of the backyard, that is if yard work ever became sexy. I write about everything about indoor and outdoor gardening and the dread-it-but-still-need-to-do-it chores around the yard, like cleaning out the gutter guards.

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