How to Revive Old Soil in Containers

Do you garden in pots?  When it comes to container gardening, dirt cheap may not always be a bargain.

You may have already spent around $8 to $10 per container just to replenish your potting soil.  Since most potting mixes contain peat-based ingredients, they might break down fast, especially if you’re planting veggies such as:

• cucumbers
• tomatoes
• cabbage

which use a lot of nutrients throughout the year and cause faster nutrient depletion in the soil.

How to Revive Old Soil in Containers

This is why rejuvenating your old potting soil, instead of replacing it every season, is financially and environmentally beneficial.

Can you reuse your old potting soil?  YES, you can!

Here are some helpful tips on how you can start to revive oil soil in containers.

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Sterilize the Potting Soil

The first step in rejuvenating the oil potting soil in your garden is to pasteurize or sterilize your old soil.  This will remove pests and microbes.

Even if the plants you’re growing in the soil are growing healthy, it’s still a good idea to sterilize your potting soil first.

There are three methods of sterilizing potting soil:

1. Solarizing

This is the easiest method which involves placing the old soil in large black plastic bags or a 5-gallon bucket with lid. Then place the containers in a sunny spot in your garden or outside your house for four to six weeks.

The heat that builds up inside these containers will kill the harmful organisms in the soil.

2. Baking

You can also bake the soil in an oven at 200 degrees Fahrenheit for about 30 minutes or place it inside a microwave for 90 seconds.

One thing to keep in mind with this method is that although it’s faster, it tends to release nasty odors.

3. Soaking

Put the used soil in a bucket with several small holes at the bottom then fill it with water.  Let the water drain out then repeat the same steps.

After the water is drained for the second time, spread the soil on a tarp or large plastic cover and leave it in the sun to dry. 

Feed the Soil

Now that it is sterilized and free from harmful organisms, you can start feeding your “new” soil.

Add your slow-release fertilizers (4 tbsp of fertilizer per five-gallon container).  You can also add in some generalized fertilizers with balanced Nitrogen, Phosphorus, and Potassium.

For every five gallons of soil mixture, you can also add in about 10 to 12 ounces of worm castings.  Or, instead of worm castings, you can also have a 50/50 mix of old potting soil and new compost.  

This will help kick start the soil with beneficial microbes that will help to breakdown the organic fertilizer and organic matter for your plants.

But before you start using your “new” soil again, add enough water to lightly moisten the mixture then put it aside in a plastic storage bin to cure for about two weeks. 

The microorganisms from the compost will spread through the mix.

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Start Planting!

Your renewed potting soil is now ready to use.

Reuse your clean potting soil for:

• vegetables
• houseplants
• herbs
• flowers

The prices of potting mix are skyrocketing, and like a lot of people, you may not want to spend more money, but still want great quality products.  Then, reviving old soil is the key!

Happy gardening!