We all know how it goes; you buy a bag of potting soil, use half of it, and the rest gets pushed to the back of the shed to be forgotten. Then one day, you dig it out, and you have to wonder: Does potting soil go bad?
The quick answer is yes; potting soil will eventually go bad if it is kept for too long or stored incorrectly.
Obviously, you don’t want any gardening supplies to go bad before you use them; it’s inconvenient and a waste of money. Luckily, we are here to help make sure that never happens again.
In this article, we will explain what potting soil is and let you know what to look out for if it has gone off. We’ll also throw in a few tips to store your potting soil to keep it fresh for longer.
What is Potting Soil?
Before we answer the question of the day, we need to get to know potting soil a little bit better, starting with the ingredients and their function.
The ingredients that go into most potting soils are:
| Ingredient | What is it? | Purpose |
| Perlite | Volcanic material | Soil aeration, improves drainage |
| Pine Bark | Shredded organic material | Moisture and water retention |
| Vermiculite | Mineral | Adds nutrients, improves water retention |
| Peat Moss | Fibrous organic material | Fill of nutrients like nitrogen and phosphorus |
Basically, potting soil is a substrate used for growing many kinds of plants in a pot or container. It has a lightweight texture compared to regular soil, which is perfect for more delicate plants. The light structure creates an ecosystem within the pot that is simple to regulate.
Some potting soil is designed for specific plants like succulents or orchids, so they may have some unique ingredients in them to fit their particular needs.
Potting soil can be picked up from your local garden store for a relatively affordable price.
Does Potting Soil Go Bad?
The short answer is yes, potting soil can go bad, but there are a variety of ways this can happen.
When we say ‘go bad’ in most cases, you can still use the potting soil, but it will have lost its efficiency and require some extra additives to replenish it. This is because the organic matter, most commonly peat moss, starts to decompose and lose the nutritional value that it is supposed to give the plant. However, if the potting soil has been affected in another way, it could actively harm the plants you use it for.
So how can you tell that your putting soil has gone bad?
Signs that your potting soil has gone bad include:
Change in Texture
Over time, you will notice that the potting soil becomes denser and more compact. This is because the peat moss breaks down, which happens after one and two years, depending on storage.
If you squeeze some potting soil in your hand to form a ball and it has no problem staying together, then your potting soil is probably old. If this is the only issue, then there are ways that you can revive the soil that we will talk about below.
Strange Smell
We all know that potting mix doesn’t smell like roses, but it shouldn’t smell like bad eggs.
If you notice an odor when you open the bag, it indicates bacteria growth in your potting soil. The moist, dense environment is ideal for bacteria growth, especially when it’s warm. Unfortunately, this potting soil is not salvageable and should be discarded.
Mold is Growing
If your potting soil gets too warm in an enclosed space, then it will likely grow mold.
This is not suitable for use anymore if this does occur. We recommend cracking open the potting soil container slightly when the weather gets particularly warm to prevent moisture from getting trapped.
Insects are Present
Obviously, potting soil contains organic material, which can be very attractive to insects like fungus gnats.
Once they get into the bag, the insects will feed off the decomposing matter and rob it of all its nutrients. Using this soil would lead to nutrient deficient plants and root damage so we do not recommend it.
How To Store Potting Soil
The best way to make sure that your potting soil lasts a really long time is to store it right.
The trick is that you don’t want your potting soil to dry out, but you don’t want it to get overly moist either.
Our suggestion is to store the potting soil in its original bag in a sealable plastic container. Conversely, you could pour the potting soil straight into the container. This will keep excess moisture as well as bugs from getting in.
Whether your bags are opened or not, you should store your potting soil in a cool, dry place where it won’t get too hot and humid. The location you choose is dependent on the climate you are dealing with.
To prevent cross-contamination, we suggest cleaning the container with bleach and drying it out thoroughly before adding the potting soil. If you are really efficient, you can add the date to the lid of the container so you can keep track of how old your potting soil is.
If stored correctly, an opened bag of potting soil will last six to twelve months, while an unopened bag will last one to two years.
Frequently Asked Questions:
Is potting soil still good if it dries out?
If your potting soil has dried out or become compacted, there are some things you can do to revive it.
- Spread the soil out in an even layer
- Break up any large clumps
- Sprinkle liberally with water and allow it to soak in
- Leave it to dry out for a week
- Check the texture; you want it to be moist but not wet
Lastly, you can test the soil pH and use additives to raise or lower the soil pH to add the essential nutrients back into the soil.
This technique should not be used if the potting soil is moldy, smells bad, or has insects in it.
What should I do with potting soil in winter?
If you live in a very cold area, you could likely get frost affecting your potting soil.
The only thing you can do is store it according to our instructions and maybe move it to an area that won’t get as cold as a potting shed. We encourage you to bring it inside a garage or covered place if possible.
Does unopened potting soil go bad?
Unopened potting soil does not go bad, but it can become compacted over time. To improve its structure and drainage, mix in some perlite or sand before using. If your potting soil is too old and has lost its structure, it may be time to replace it.
Conclusion
Potting soil is an all-purpose growing medium that we all probably have in our garden supplies.
Potting soil will go bad after 6-12 months if opened, but there are a few precautions you can take to make sure you use it all up before that happens.
As we have detailed, storing your potting soil in a sealed plastic container is the best way to ensure that your potting soil stays fresh for as long as possible.
After this guide, you’ll never have to worry about your potting soil going bad ever again; you’re welcome!
