So, your pot plants are gorgeous one day, and then they suddenly look like they are struggling the next day. You have given them the right amount of water and sunlight, so what is going on? They do not have bugs, fungus, or bacteria, so that just leaves… the soil.
But can your potting soil expire? And if so, how long does it stay nutritious?
Yes, potting soil does go bad, as its quality does degrade over time. It can spoil if it gets a fungal or bacterial infection. It can be good for 2 years if it gets appropriate care by adding nutrients.
Depending on the type of potting soil, most can last for about one to three years before it needs replacing. However, certain brands of potting soil have been known to last longer than that with proper care.
As part of good practice, when purchasing any kind of potting soil, it is important to check the expiration date printed on the packaging to make sure you are getting a fresh batch.
Additionally, adding beneficial microbes or fertilizer can help extend the life of potting soil.
I am going to tell you about the details of healthy potting soil, proper storing, and the ins and outs of extending its lifespan…
Check Your Soil Regularly
You can buy test kits to check the nutritional value of your soil. These are great, but in my mind, they are not critical. If you use your nose and eyes, you will see if your potting soil is usable.
Smell the soil. If it has a bad smell, like rotten eggs, it is well and truly expired. Having just dumped a pot of old soil out of a pot, I cannot even begin to describe the smell.
You will know it when you smell it… It’s a foul odor that you will definitely notice once you pop open those unopened bags.
If the soil is compact and forms compact lumps, it is past its value to the plants in it.
If it has bugs in it, it will have lost most of its nutritional value as the bugs will have eaten the important nutrients for breakfast, lunch, and supper. An insect infestation will lead to bad potting soil in a hurry.
If it is moldy, it is definitely NOT usable! Mold indicates the presence of fungal spores.
What’s Inside Potting Soil
Potting soil is a combination of perlite, coarse sand, bark, sphagnum (peat moss), vermiculite, and lime. All of which are essential for good nutrition, drainage, and aeration.
Some other ingredients that are often found in potting soil mixes include growing medium options like:
- Worm castings
- Coconut coir
- Guano
- Other organic matter like compost or manure
There are recipes to make your own potting soil based on where you are going to put your pot plants and what you are planting. If you make your own potting soil, you may find that it lasts a bit longer.
How to Store Potting Soil to Extend its Shelf Life
Store your unopened potting soil in its original bag in a dark, dry spot.
Your potting soil needs to be dry to last long. If you have any carry all containers that are opaque, place the potting soil, in its original packaging, in the carry all in a dark, dry area. Make sure the carry all is air and watertight.
You can also put your potting soil in a large storage container out of direct sunlight to repel pests, fungi, and moisture.
If you are storing soil from an open packet, spread it on a tarp in the sun to dry and then store it in a carry bag.
What Should I Look for When Buying Potting Soil?
Looking at the expiration date on the potting soil is important, but it’s not the only factor to pay attention to. Here’s what you need to consider when buying potting soil.
Texture
The texture of the potting soil you choose can have a big impact on how well your plants will grow.
For example, sandy soils drain quickly and are not great at retaining moisture; clay soils retain moisture but don’t allow much air circulation; and loam soils are a combination of sand, silt, and clay and provide the best balance of drainage and moisture retention.
Depending on what type of plant you’re growing, you may need to adjust the texture accordingly.
Nutrients
The nutrients present in potting soil are also important for keeping your plants healthy.
Most commercial potting soils contain some level of fertilizer and/or composted manure that provide essential nutrients like nitrogen, phosphorus, potassium, magnesium, and calcium.
If a particular nutrient is lacking in your soil, it can be added separately in the form of fertilizers or compost.
pH Balance
Another factor to consider when buying potting soil is pH balance—the acidity or alkalinity of the soil (measured on a scale from 0-14).
Different plants prefer different levels of pH balance; for example, most vegetables prefer slightly acidic (6-7) soils while roses prefer slightly alkaline (7-8) soils.
Certain types of potting mix will also be labeled as “neutral” if they have a neutral pH balance that works with many different types of plants.
Refresh Your Potting Soil to Reuse it
Want to use old potting soil? In most cases, potting soil can be reused if it has a healthy plant in it and is still nutrient rich. Dry it out properly if you are storing it over the winter and get a booster from your local nursery to mix in before use.
Make sure there are no insects (like fungus gnats) , fungus, or bacteria in the soil. Follow your nose! If it stinks, do not use it.
Transplanting Pot Plants into Fresh Potting Soil
If you see your pot plant is struggling, or you just need to repot it into a larger pot, remove it from the pot it is in by gently shaking the pot to loosen the plant to slide it out of the current pot.
Gently loosen the roots and shake out as much of the old potting soil as possible off of the roots before repotting your plant.
Extend the Lifespan of Your Potting Soil
If your potting soil is still dry, bug free, fungus free, and healthy, but your plants are not thriving, you can refresh the soil by the following methods.
Use Compost or Manure
Adding compost to your potting soil is a great way to give it an extra boost and keep it healthy.
The compost will add valuable nutrients to the soil, which will in turn help your plants grow stronger and more vibrant.
To get the most out of composting, be sure to use organic materials such as grass clippings, leaves, kitchen scraps, and other organic waste materials.
Manure is another great way to extend the life of your potting soil. It adds essential nutrients such as nitrogen, phosphorus, and potassium that help promote plant growth.
Be sure to use well-aged manure that has been properly composted before adding it to your potting soil or garden beds. This will ensure that any harmful bacteria have been eliminated before you introduce them into your garden environment.
Aerate With Perforated Containers
If your potting soil has become compacted over time, it may not be able to retain water or allow air flow effectively anymore.
To combat this issue, try using perforated containers or blocks in order to aerate your potting soil and restore its ability to retain moisture and allow air flow through it again.
What to do with Old Potting Soil
If your potting soil needs to be replaced, do not simply throw the old soil away.
Rather, add the soil to your compost heap, or use it as topsoil for your lawn, or – if it is bug- and fungus-free – top up other pot plants.
When you add an opened bag of potting soil that has passed its expiration date to the compost pile, you’ll be benefiting the compost by adding organic material that will break down quickly!
Tips
When potting your plants, lay out a plastic bag or tarp under the bag and where the pot is. Catch any soil that falls off your trowel. Potting soil is very dry and powdery, moving it always is messy. Scoop up the soil from the plastic to use.
Keep your pots elevated so that water can drain out properly. Lift them off the ground by standing the pots on bricks. Improper drainage can cause root rot and provide the ideal breeding ground for fungus, pathogens, bacteria, and bugs.
Do not over water your pot plants; plants do not need as much water as one would think. Too much water is not good for your plants.
Place your pot plants in the right spot. I cannot stress this enough. You can buy the best potting soil, but if your plants do not have the correct amount of light, they will not do well.
Mix in a small amount of compost or fertilizer as potting soil is actually soilless and therefore does not provide nutrients for the plant.
FAQ
Yes, there is a difference. Depending on the manufacturers, potting soil may have soil in it, potting mix has no soil in it making it safer for plants as it does not contain pathogens.
Potting soil should have pine bark, peat moss, vermiculite, or perlite in it. It should be very powdery to give good drainage.
You can use garden soil to pot plants; however, it is not an ideal choice. Potting soil provides drainage, aeration, nutrients, and moisture control for your potted plants. You will need to add nutrients and maintain the soil carefully and you will also have to have very good drainage.
Old potting soil is great topsoil for your lawn. You can also mix old potting soil with new soil – if it is still healthy – to make your soil go further.
So There You Have It…
Potting plants is a great way to brighten up your garden. People talk about functional gardens that are either for vegetables or for flowers.
The truth is, if you want to grow vegetables, or if you want your flowers to grow beautifully, you need pollinators! Bring in loads of beautiful colors to attract bees and butterflies.
Planting plants in pots is also very sensible way to garden if you have extreme weather. They can be taken indoors in winter – mine go into my greenhouse in winter – to protect them from frost or snow.
If you ensure your pot plants have good drainage, your potting soil can last 2 years or more. If you are investing in pots and in plants, remember that the quality of your soil is going to be the key to join the pot and plant together to give you beautiful flowers.
Di-Anne Devenish Seebregts was raised in an environment where daily life consisted of hiking, environmental conservation, growing fruit and vegetables, and raising poultry for meat and eggs.
She combined her passion for the writing word with her love of the pride that comes with not relying on others. She raised three children (who are now adults) to value the environment, and understand the value of being self-sufficient.