So, you finally have some free time and you want to use it in the best possible way – by planting some new greenery around the house. There is just one thing – all the soil you have is pretty old since you bought it a few months ago and you’re not sure is it still useful.

Have you ever wondered does potting soil go bad or does potting soil expire? It does expire because peat moss (it’s primary ingredient) has a really short lifespan of up to two years.

Now, the answer alone is never enough. Let’s see why and how it goes bad, and also how to know if your potting soil is bad (+some tips on how to preserve it and make long(er)-lasting.

Does Potting Soil Go Bad or Expire?

Obviously, it does. This is why it is important we know what is the shelf life of the potting mix.

Make sure you check the expiration date on the bag before you use the soil. It usually lasts for a year or two.

Now, the answer to the question ‘how long does garden soil last’ may get you a little confused.

In general, we consider soil to be mostly dirt, so how can dirt expire, right?

Well, the soil is not just plain dirt but rather a mixture of a couple of different ingredients. Some of those ingredients might go bad. The ‘expiration date’ of those ingredients affects how long will soil last.

Soil Ingredients

soil ingredients

Now, let’s take a closer look at the ingredients that make up potting soil. 

When we observe the ingredients, it becomes easy to conclude how long is potting soil good for, and why.

Of course, the ingredient ratio (and the ingredients themselves) differ from brand to brand, but some of the components are indispensable

Vermiculite

Vermiculite is a high-absorbent mineral mined from different parts of the world such as Russia, Brazil, China, and South Africa. It doesn’t expire since it is a mineral.

Perlite

Perlite is a type of volcanic glass. It helps drainage and prevents waterlogging (just like vermiculite). Of course, it can’t expire either.

Pro-Tip: If you are making your soil mix at home, regular sand is a great substitution for perlite.

Pine Bark

Pine bark is one of the main ingredients in most potting soils on the market. Logically, it comes from real pine trees.
It provides insulation during cold weather and sustains soil humidity during hot weather. Pine bark shouldn’t expire since it is a natural ingredient.
Still, different brands often add pine bark extracts that sometimes can go bad.

Peat Moss

Peat moss is used for preserving water since it has been known to be able to keep large quantities of water. The problem is, it starts decomposing right away.
Does peat moss go bad? Yes, it does.
Peat moss is the answer to our question ‘how long does potting soil last’. It lasts just as much as the peat moss in it does.
When it starts decomposing too much, it will cause you trouble.

Can Potting Soil Go Bad

We’ve concluded that potting soil expires due to peat moss decomposing.

But, can potting soil go bad (to the point it becomes unusable), and harm your plants? Unfortunately, yes, it can, and now I will explain how and why.

Bad Potting Soil Prevents drainage

Low drainage is often a consequence of using expired potting soil.
Simply, since the peat moss decomposes quickly, at one point, it will decompose in a way that will prevent water from running.
This way, drainage is disabled, and you know what that means – your plant is in great danger of living in a waterlogged pot and eventually dying from overhydration.
Nonetheless, compressed soil will prevent oxygen circulation as well.

Salt accumulation

Just as water accumulates in the expired soil, so do plant food and fertilizers. This way, minerals, and salts accumulate. The consequence of amassing – the plant gets dried out.

How to Know Potting Soil is Bad

How to Know Potting Soil is Bad

1. Expiration date of Bad Potting Soil

Well, this one is pretty logical.
If you are wondering how long does potting soil lasts in the bag, just go ahead and check the expiration date. It has to be printed on the bag.
You might have to look for it a little, but this is the only way to make sure you’re not using expired potting soil.

2. Mold

Mold often appears in expired soil. If you notice it, stop asking yourself ‘can soil go bad’? It already did.
Mold appears in dark, shady, and humid conditions. This means you have stored it improperly. Still, this is nothing that a little bit of sunlight can’t solve.
Just put it out on the sun and let all the soil get completely dry. This is the only way to get rid of the mold.

3. Gnats

Fungus gnats live in soil and propagate in it.
Sometimes, if the soil isn’t sealed properly, they will invade the soil and start laying eggs in it. If this is the case, there is not much to do.
It is for the best to just toss away the soil.

4. Bad odor

If this happens to be the case, trust me, you won’t be in doubt.
The smell is horrible, like rotten eggs.  Of course, if your soil becomes stinky, the only way to go is to the dumpster.

How to Store It During the Winter

When you are not planning on using the soil for a long time, it is of huge importance to store the soil properly.

Use a fresh and clean container with a lid on it. The soil must be fully covered so you’d prevent gnats and other intruders from ruining it.

Let the soil get completely dry before you store it over the winter. This way, you prevent mold from appearing.

If you have a new, unopened bag of soil, you can simply put it in a container and wait until you’ll want to use it. Of course, an unopened bag has a lower risk of being contaminated.

How to Rejuvenate Bad Potting Soil

How to Rejuvenate Potting Soil

Does soil go bad – it sure does (I’ve explained why this happens). But, is there any way to rejuvenate the old soil?

Maybe it has expired, but it doesn’t have any of the other signs of expiration? Of course, you can use it in a way that might be acceptable.

1. Mix It

For example, you can mix a smaller ratio of the expired soil with some new soil and use it for low-maintenance plants that don’t require high-nutritional soil.
Add some new soil and blend it nicely, so you can’t differ the two soils anymore.

2. Add Nutrients

You can also add some slow-release fertilizer or liquid fertilizer and enrich the soil.
If you chose this way of rejuvenating, I recommend adding some fresh soil, just in case.
Blend it thoroughly.

3. Add Water

If your soil is too compact, maybe adding some water might help. But, be careful! You don’t want to add too much and make the soil soaking wet.

4. Add Perlite

We’ve already talked about the use of perlite – it prevents waterlogging.
You can add some extra perlite (or sand) to the mixture and slow down decomposing peat moss this way.
Just make sure you don’t add too much (except if you are making a mix for plants that can survive in low-nutrition soil, such as cacti or sempervivum).

In general, if you ask me how long does garden soil lasts, the answer is mostly – proportional to the care you give it (just as to your plants as well).

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How to Use Old or Bad Potting Soil

If you can’t help it and have to toss away the soil, there are still some ways it could be useful. For example, you can add it to the compost. It won’t do it any harm.

Nonetheless, the nutrients will be beneficial. You can also use it to fill up some holes around your yard or garden.

Of course, you can spread it around your garden, as well. There is no reason to dig it in, the rain will do it for you!

Needless to say, if gnats appear, or the soil has that disgusting odor we’ve talked about earlier, it is for the best to throw it away.

Conclusion

As you have seen, the answer to the question ‘can soil go bad’ is sometimes hard to answer. In general, yes, it can go bad.

On the other hand, there are multiple ways to react when it goes bad. If you can’t save the soil, it can still be used for some other purposes. The main thing is to take a closer look at the soil and see what can you create from it.

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