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Can Potting Soil Go Bad?
Can potting soil go bad? Does it go off? Do you need to change it? Or can you just keep reusing the same potting soil forever? If you’re looking to pot up a plant and you have an old bag of potting mix sitting around then it can be very tempting to use it. It’s better than the soil going to waste right? And it means you don’t have to go out and buy a new mix. Although you may be able to reuse the potting soil or use it if it hasn’t been used before, there is a possibility that your soil won’t be very beneficial to your plant anymore.
The longer a plant is in a potting mix, the more nutrients will be extracted from the soil to feed your plant. Meaning that old potting soil can be severely lacking in the nutrients your plant needs. Old soil can also build up excess salts which you don’t want in your mix. Old soil may also dry out completely and become hydrophobic meaning it’s unable to absorb water which can be a quick way to kill a plant. It’s also possible that individual elements within the mix can go off.
But it’s not just soil that’s in potting mix. There are other elements we often include that need to be considered when asking can potting soil go bad. One of the main components that gets added to potting mix is perlite. Perlite are small pieces of volcanic rock that are used to aerate soil and help with drainage. They are a great addition to potting soils that need loosening up to be made lighter for those plants that need a bit of extra drainage. Perlite shouldn’t go bad and it should be fine to be reused as the plant isn’t getting nutritional benefits from these tiny rocks.
The next common addition to potting mix is peat moss. Unfortunately peat moss does seem to have an expiry date. If kept properly, peat moss can last around two years before it needs to be replaced. Peat moss is a great way to help plants retain their moisture but when allowed to dry out it can become hydrophobic which can be devastating to the type of plants that are usually potted with peat moss. If you notice your peat moss drying out take it out of the mix and rehydrate it or replace the peat moss after two years.
So can potting soil go bad? It doesn’t go bad like off milk but it can go bad in that it can cause harm to your plant. How do you know when your soil has gone off? Let’s take a look at some of the common signs.
Is Your Soil Mouldy?
One of the easiest things you can do is take a look at your soil and see if it’s mouldy. Mould is quite easy to spot and often looks like white fluff on the surface on the soil. Sometimes you’ll be lucky and the mould is only on the top. If this is the case you can often scrape the mould off and use the soil underneath. If the soil is mouldy all the way through then it probably isn’t appropriate for your plants.
Is Your Soil Hydrophobic?
Look at your potting mix and feel it. Is it bone dry to the touch, can you pull the soil out of a pot with ease. If you water it does the water soak into the soil or does it repel and run down the sides of the potting mix? If your soil has become hydrophobic then it’s incredibly important that you rehydrate it before using it with a plant or your plant could die of dehydration. Find out about potting mix that won’t absorb water here.
Smell Your Potting Soil
The first obvious sign is a bad smell. If you’re not sure if your potting soil is good to go or not then try giving it a smell. If it smells foul or unlike soil then there’s a chance that plant matter or peat moss has rotted in the soil and it won’t be good for your plant. If your soil doesn’t smell good then get rid of it, it shouldn’t be getting used on your plants.
Does Your Potting Mix Have An Expiration Date?
This is a relatively easy one. Look at the back on your potting mix, does it have an expiration date? If it does and it’s gone past it then it might be time to replace your mix. If you’re using peat moss that’s older than two years old then it could be time to replace that peat moss.
Does Your Mix Have Pests?
If pests have gotten in your mix then it might be easier to get rid of the soil rather than trying to eliminate them. Of course you can try to rid your soil of pests but if you miss a few and they start breeding again it can be devastating for your plant. If you notice small insects in your soil or lots of flying ones around it then it could be time to get rid of your potting mix and replace it.
We hope we’ve managed to answer your question of can potting soil go bad. Although we don’t mean the soil it rotten, it can definitely get to a place where it is bad for your plants. So it’s very important to recognise this and learn how to work against it or prevent it from happening in the first place.
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