Can Potting Soil Go Bad?
Unarguably, good quality soil is essential for a healthy plant. And potting soil has proper texture and nutrients for indoor plants to grow, breathe, and thrive.
You can also use potting soil for outdoor plants, though not a necessity as they already have direct sunlight, an open environment, and natural drainage. But, does potting soil go bad? Can your stored potting soil effectively support plants?
Potting soil goes bad after extended storage. But in reality, it doesn’t become totally unusable but loses the texture, moisture levels, and nutrients level over time as the organic components decompose. And the rate of decomposition is higher in improperly stored potting soil.
The soil becomes denser and dustier as the peat moss and pine bark rot. Hence, less aeration, lesser water and nutrients circulation, and lower ability to sustain healthy plant growth. To extend the shelf life, keep your potting soil in airtight bags and away from direct sunlight and a damp environment.
- Can I Use Garden Soil for Potted Plants?
- Can I Use Potting Soil in the Ground?
- Potting Soil vs. Garden Soil
What Makes Up Potting Soil?
Indoor plants need as much nutrients, aeration, and good drainage as outdoor plants. To give as much of these as possible, the potting soil contains some or all of the below materials:
- Vermiculate: It’s a type of phyllosilicate mineral rock mined in parts of South America, Russia, and South Africa. Vermiculate creates more air channels within the soil for better soil aeration and drainage.
- Perlite: It’s an obsidian-sourced volcanic glass material. And like vermiculate, it helps reduce soil compaction and hence better aeration and drainage. Perlite also forms an excellent medium for growing roots on plant cuttings.
- Pine Bark: As the name suggests, pine bark is from real pine trees. They can be flaky, thick or skinny structures depending on the tree species. It serves as mulch within the potting soil to help keep moisture for long.
- Peat Moss: Also called sphagnum, and is a type of plant of the Sphagnaceae family. Peat moss retains enormous amounts of water and boosts the cation exchange capacity and capillary of potting soil. Thus, the soil has more water and nutrients for the plant.
The above nutrients keep the soil lightweight, well drained, and high in nutrients to keep your edibles and ornamental plants well nourished.
How Long Can You Store Potting Soil?
Properly stored potting soil retains considerable quality for about 6 to 12 months. If kept with its packaging bag unopened and away from direct sunlight and dampness, the soil lasts for about 1 to 2 years.
However, as earlier noted, the organic materials within the soil deteriorate naturally over time, and even the best-kept potting soil loses quality with every passing day.
You may also find these tips for storing potting soil over winter helpful.
How to Know if Your Potting Soil is Bad
Whether you buy or make your potting soil, it’s common to have some extras post-planting time. Yes, the directions for use say you can store the extra potting soil for next season, but will it be as effective as freshly made potting soil?
Bad soil can’t support plant growth adequately. Though very unlikely unless stored for overly long periods, bad potting soil will have the following signs:
- Have a rotten egg smell from growing anaerobic bacteria.
- Have insects and pests such as fungus gnats that eat rotting matter.
- The presence of dusty looking, yellow, white, or green molds
- Becomes dense and compacted
- It has stayed past its expiry date
Can You Use Old Potting Soil?
Old potting soil does not necessarily mean the soil has gone bad. You only need to rejuvenate the old soil to renew it for usage, as long as it has no signs of bad smell, molds, or insects and pests infestation.
Add a handful of perlite to slow the decomposition and some compost to boost the nutrients and moisture-holding capabilities.
You can use old potting soil in the following ways:
- For Your Outdoor Garden: Old soil is quite valuable for your outdoor garden, and the direct sunlight and natural aeration eventually rid it of ominous quality signs. But you should spread it over the garden and let it mix with the garden soil slowly over time.
- Put it in the Compost Pit: Putting it in your compost pit helps to add organic matter and volume to your hole. Shoveling the old potting soil on the compost heap helps recycle the lousy soil.
- Add some to the worm bin: Worm castings are great resources for plant roots, and require wet newspapers and soil to set up. Why not add some of the old potting soil into your worm bin?
Does Potting Soil Go Bad? Final Thoughts
Potting soil can go bad if improperly stored. It will also lose its freshness, nutrient and moisture levels, and effectiveness over time. And how long it stays fresh depends on the storage environment. Even so, old potting soil is revamp-able and usable for other purposes like compost pits, worm pits, and outdoor gardens.