Does Potting Soil Go Bad?

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potting soil mix

Is it the end of the growing season in your neck of the woods? What should be done with containers that had plants growing in them all summer? Did you buy some bags of potting soil from the store, but never used them and stored them in your garage for a few years? If any of these ring a bell, you might be wondering:

Does potting soil go bad? For the most part, no it does not! As long as your potting soil does not have a foul smell, a bad insect problem, or a disease issue, it is perfectly fine to use to grow your plants successfully!

Even though potting soil may be old or used over and over, it can still be used again the next season! However, this probably does mean you will have to give it a good jump start to get it back to its top form!

Read on to learn about what makes a good potting soil and how to preserve and rejuvenate it each time it is used.

What are the Basic Contents of a Good Potting Soil?

Any good potting soil is lightweight and does not compact easily. The plant and the soil is going to be confined to a small space, so it’s really important that the roots can breathe in that soil.

Potting soil also must drain water very well, and the container must have adequate drainage holes to let that water out. It is important to be sure the plant’s roots don’t drown!

Since garden soil does not drain water well, it should not be used in pots or containers. Potting soil or seed starting mix can be purchased at a gardening store. While these pre-made mixes can be convenient to use, they could contain man-made nutrients that I do not recommend.

In order to save money and stick to be being organic, I make my own potting mix and have had great success! Here is a full detailed article I wrote explaining the process of my homemade mix: DIY Potting Soil and Seed Starting Mix to Save Money. I mix four parts peat moss to one part vermiculite and one part perlite together to make my potting mix. These ingredients provide a lightweight, breathable and moisture controlled environment for containers. You can check out our Best Soil Amendments products page to help you get started!

This mix alone doesn’t really have many nutrients that your plants need in order to grow and thrive. This is one reason it never really goes bad.  It is organic material that doesn’t break down very fast when used in a container. When starting fresh with my potting mix, I add organic nutrients such as compost or worm castings. This will give your container enough nutrients to last the entire growing season of a plant!

When the season is over, potting soil does not have to be thrown away!  Save time and money by not having to make a new potting mix every year.  If it is stored properly and given a good jump start next season, it will be perfectly fine to use for container plants!

How Should Used Potting Soil be Stored Over Winter?

To prevent mold, mildew, fungal, disease, and pest problems from infesting your potting soil over the winter, here are a few steps you can take.

First, old plants and any big clumps of roots should be removed completely from the containers. Also, I recommend that potting soil not be stored in growing containers! Most likely, containers are a solid material that could crack when the temperatures freeze and the soil expands. It is also recommended to let the soil dry out to prevent mold and mildew problems.

Find something clean to use to store the potting soil. This could be a new trash bag or a washed out plastic bin or trash can. I recommend using a natural cleaner to do so!

If you are storing unopened bags of potting soil, you can just place the bags in the container. If the bags are already opened, just pour in the used potting soil, seal the container and store it in a dry place! Now let’s learn what to do when it’s time to use this soil again next season!

How to Rejuvenate Your Potting Soil Next Season?

When Spring comes around and it’s time to start planting in containers again, get out the stored potting soil! But WAIT! It will need some boosting before it can be used!

Add more potting soil.  If the quantity of old potting soil isn’t going to be enough, it is perfectly acceptable to add more to it. I mix and add 4 parts peat moss, 1 part vermiculite, and 1 part perlite to my potting soil.

Water!  Your soil will most likely be dry, as it should be, so it will definitely need some water. I usually put my soil in a wheelbarrow and continue to spray and mix the soil together until it is thoroughly moistened. If you squeeze a handful of the soil, a few drops of water should drip out. That is the optimal amount of moisture. If more than a few drops of water drip out with a squeeze, then the soil is too wet.

Add more nutrients! Even though you hopefully added nutrients to the potting mix last year, the plants grown in that soil likely used most of them to grow; therefore, this soil is now considered depleted. This is also true for the soil out in the garden. It is very important to give back to your soil each year. For potting soil, mix in 1-2 inches of compost to the top of the soil and you could also mix in a cup or so of worm castings if you have them available. If you haven’t started making your own compost (you should start now!) you can buy a granulated organic fertilizer from the store to add to your mix.

We have now written a full article on fertilizer for containers that you can read here: Does Potting Soil Need Fertilizer?

“A generous person will prosper; whoever refreshes others will be refreshed.

Proverbs 11:25

Other Ways to Re-Use Old Potting Soil

Some of you may not have a convenient place to store a bunch of potting soil over the winter. Have no fear, there are other useful things you can do with it! Just don’t throw it away!

Spread it out on top of your garden. This is a great way to add organic matter to your garden. Just spread it out on top of your garden beds and let nature do the rest! Do not till or dig it in. Do not disturb your garden soil!  The rain, snow, and worms over winter will naturally sift the material into the soil. Other than potting soil, I always recommend adding a layer of compost and then mulch on top of the garden before winter.

Add it to your compost pile. I am continuously adding garden waste to my compost pile throughout the year. It will all break down and get added back into your garden, strengthening the soil and, in turn, the plants grown in that soil! The end of the fall season is when I top off my garden beds with a layer of compost about one to two inches deep.

Add it to a worm bin.  Your potting mix would be a great thing to add to your worm bin as extra organic matter and bedding. You can also add shredded leaves, paper and cardboard.

Give it to someone else!  If all else fails, at least give it to someone else instead of throwing it away!

Check out Our Favorite Products page to find everything you might need to help make your garden a success!

Related Questions

Can potting soil get moldy?  Yes, potting soil can get moldy. In most cases, however, it doesn’t mean it cannot be used. You can mix in some compost to incorporate good life back into the soil. The only case where you would not want to use moldy potting soil is for seed starting.

How do I moisten dried out potting soil? Put your dried soil into a wheelbarrow or bucket. Continue to add water into the soil while mixing it up at the same time. Keep mixing in water until the soil is dark and has the consistency of a wrung out sponge.

How do I dry out potting soil that is too wet?  If your potting soil is too wet you can spread it out in a wheelbarrow or on a tarp and let it dry out in the sun and wind.

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Corey Leichty

Hi, I’m Corey and I love using gardening as a way to provide food for my family, learn life lessons alongside my wife, Andrea, and teach life lessons to my two sons. Do you have gardening questions? Not finding what you are looking for? Please feel free to Ask a Question (Click Here!) and I will get back with you as soon as I can!

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