When it’s potting time, you may buy some bags of potting soil and not use all of them at once. Sometimes you have some of the used potting soil sitting around, and you don’t know if it is still good to use. So, does potting soil go bad?
Yes, potting soil can go bad.
An opened bag of potting soil will go bad after 6 to 12 months, while unopened potting soil will remain fresh for up to 2 years if stored in a cool and dry place. You can tell your potting soil has gone bad if it is compacted, has mold, insects, or produces a foul odor.
Problems with old potting soil
Potting soil can remain fresh for a long time when stored properly. However, it won’t be as potent as new potting soil.
Here are some issues with old potting soil:
- Degraded nutrients: The quality will continue to degrade when unused over a long time. You might want to test for nutrients before using old potting soil.
- Moisture loss: When potting soil stays too long without being used, it loses moisture and dries up.
- Damaged texture: Over time, soil particles clump together, making the soil lose its texture.
- Compaction: Moisture loss leads to compaction, making the soil less draining.
The longer the potting mix stays without being used, the more microorganisms break down the organic matter, making it less nutritious for potting plants.
How long does potting soil last
Unused potting soil can last about 6 months if stored properly before losing its quality. To increase its shelf life, store potting mix sealed in its original packaging and put it in a protective container such as a storage tote. This will make the soil last longer than when exposed.
Storing your potting soil and mix in a climate-controlled place will make it last longer. Extremely high or low temperatures can affect the quality of the soil, making it go bad quickly.
Signs your potting soil has gone bad
Although it is a good idea to reuse potting soil and potting mix, you have to be careful not to pot your plant in damaged soil. Expired potting soil may be infested with pests such as gnats and can be detrimental to your plants.
Here are signs that your potting soil has gone bad:
A rotten-egg smell is a sign that your potting mix has gone bad. It comes from anaerobic bacteria that thrive in compacted soil with less oxygen.
You can fix this bad odor by killing the bad bacteria in your spoiled potting soil. Spread the soil on a surface in the sun and allow it to dry. The sun will kill the bad bacteria.
Presence of pests
The presence of little insects crawling all over the soil could also mean the soil is rotting and may not be very usable. Fungus gnats are the most common pest because they infest rotting matter.
Fungus gnats may not harm mature plants but can really cause root damage to young plants.
Do you see dusty-looking mold on potting soil? It could be white, yellow, or green. If yes, then that’s a sign that your potting soil has gone bad.
A good solution is to place the soil in a well-ventilated area, preferably in the sun, to eliminate the mold.
Do not use potting soil that’s infested with mold because it can cause root rot in your plants. Soggy potting soil is vulnerable and highly likely to grow mold, so you should be careful handling it.
If the soil has gone bad and is not usable, throw it away. However, if the mold is not too much, treat the potting soil with an antifungal remedy to prevent root rot from affecting your plants.
How to reuse old potting soil
Before using old potting mix, inspect it to ensure it is not infested with pests and disease.
Put it in your compost
Instead of throwing away your potting soil, add it to your compost pit to add volume and organic matter. Simply spread it over the compost heap to add to the decomposing matter.
You’ll have recycled your potting soil after it expires. You may notice small perlite particles even after the compost decomposes, which shouldn’t worry you.
See also: Are tea bags biodegradable in compost?
Add to a worm bin
If you’re setting up your worm bin, you may need some materials, such as soil and wet newspaper to make the bin healthy and functional. Old potting soil can be useful in this case.
Throw it in your outdoor garden
That soil in your planters may be depleted and the nutrients broken down and used by your indoor plant, but it is not entirely useless. Add it to your outdoor garden when you think the nutrients are depleted.
It will help add volume and more organic matter to your garden soil.
Does used potting soil expire?
Used potting soil is less potent than fresh soil due to spent peat moss and nutrients. However, you can reuse it within 6 months of opening the bag; otherwise, you’ll need to rejuvenate the dirt before using it.
Do not throw the soil away. If you used your soil last season, you could add fertilizer and pot your plants with it in the new season.
Most potting mixes will go bad after 6 months to 2 years, depending on how you store them. The organic matter and nutrients in the soil break down over time, making it less fertile. Some bags of potting soil have an expiry date, but you can still add them to your compost instead of throwing them away.
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