Most potting soils contain peat moss and other organic ingredients that decompose over time. This causes the soil to lose its aeration and water retention capacities, making it detrimental for any potted plant.
Adding old soil to your veggie patches or flowerbeds is one way to use it. But if you don't want to add it to plants directly, you can compost it instead. That said, old potting mixes can have low nutrition, excess salt, and various other issues you need to address before reusing them.
Potting soil has gone bad if it has a foul odor, mold growth, pest infestation, a compacted texture, or if it fails to retain moisture properly.
In the previous growing season, plants used nutrients in the potting soil that were added when it was manufactured. Nutrients also leach out from the soil as plants are irrigated. Gardeners who opt to reuse potting soil this season will need to improve the porosity and fertility of the soil before planting new plants.
Soil is resilient and it can be brought back to life, which is good news. The first step in this process is to amend the soil to provide nutrition and enhance the ability of the soil to retain moisture.
Revitalizing soil isn't a one-and-done deal where you test the soil, add in a bunch of organic material, and then forget all about it. It's a process where you'll need to regularly add in more organic material and nutrients over time, until it reaches a point where it's able to support a healthy ecosystem on its own.
Potting soil does not necessarily go bad if not used, but its quality can deteriorate over time. The shelf life of potting soil is typically one to two years when stored properly.
Compost heap - Here is the easiest option of all: Simply toss the old soil or unused half-bags of soil right on the compost bin. A good compost pile should be a balanced mix of green material, brown material and soil.
Old mix can, however, be sterilized for reuse. It will not be as fresh, but the sterilization process will ensure it is pest and disease free. In fact, I sometimes sterilize fresh seedling mix when I am starting prized seeds.
Worms aerate the soil, allowing better circulation. They also eat organic material, so a big worm population means your soil is rich in nutrients. Look for earthworm casts or burrows on the surface of damp soil.
The quick answer is yes. Old potting soil loses value over time as its ingredients, like peat moss, decompose. But don't worry, you can easily revive your old potting soil back to health.
Look at where live plant roots touch the soil, this is the area where most of the microorganisms in the soil live, because that is where the food is! If soil sticks to the roots of living plants that you dig up, it shows that those plants have sugar on their roots and organisms are coming there to eat the sugar.
Cracked Or Dry Soil
For example, soil erosion from wind or excess rainfall can cause a property to become dry and dusty, making it hard for plants, trees, or grass to survive. In addition, soil can become cracked or dry due to low rainfall or little to no regular irrigation.
Potting soil is sterile, which is good for indoor plants because it prohibits fungus. But outdoors, it won't retain any nutrients, in part because water leeches through it so quickly, taking what little nutrients there are with it. Grass will not thrive without rich nutrients in your garden soil.
Soil recycling is beneficial for the environment as it reduces energy consumption, greenhouse gas emissions, and the amount of waste sent to landfills. Recycling organic matter creates compost, rich in humus and humic acids, which serve as a natural pesticide.
If plants died from bacterial, fungal or viral disease, then you definitely do not want to reuse the soil, as soilborne pathogens can still be present and active. However, if the plants that grew in the soil before were healthy, it is generally OK to reuse the potting soil.
It's generally fine to reuse high-quality potting soil if whatever you were growing in it was healthy. But can you reuse potting soil that's been home to pests? If you noticed pests or diseases on your plants, it's best to sterilize the mix to avoid infecting next year's plants.
Miracle-Gro plant food isn't technically harmful to plants even after it has expired or gone past its shelf life. It still has nutrients and doesn't contain toxins that could harm your plants. This applies to all types of plant foods including liquids, granules, and water solubles.
That potting soil is worn out because the peat moss has decomposed. That peat moss can decompose even if you never take it out of the bag. If your potting soil has been sitting in your shed since last year in an opened bag and it's gotten wet, toss it. If it somehow stayed bone dry, it should be OK to use.
Add Organic Matter
Organic matter will loosen hard clay and bolster sandy soils, providing a better balance between moisture retention and water drainage. Examples of organic matter include manure, compost, shredded leaves, and grass clippings.
For an added nutrient punch, add approximately 1 tablespoon of time-released fertilizer per gallon of potting soil mix. Viola, the once spent potting soil is now ready to once again super charge plants providing them the nutrients needed for optimal growth!
The current high erosion rates throughout the world are of great concern because of the slow rate of topsoil renewal; it takes approximately 500 years for 2.5 cm layer of fertile topsoil to form under agricultural conditions.