How to Cook Your Own Potting Soil

Soil straight from the garden should not be used in pots.

Shelling out for bags of new potting soil each year for container plants and seed starting can add up. With the soil already in your garden and a few other ingredients you can make your own potting mix. The key is to kill the weed seeds and bacteria present in outdoor soil and to lighten soil to improve drainage and lessen the changes that it compacts and hardens in your plant pots.

Things You'll Need

• Garden soil
• Aluminum foil
• Trowel
• Rimmed cookie sheets
• Perlite
• Peat moss
• Wheelbarrow
• Clear plastic sheeting
• Shovel

Instructions

Baking Method

1. Cover a large rimmed cookie sheet or shallow baking dish with aluminum foil. Preheat your oven to 250 degrees Fahrenheit.

2. Shovel a 2- to 3-inch layer of garden soil onto the cookie sheet with a trowel. The soil should be moist, but not wet.

3. Cover the pan with more soil and insert a food thermometer into the soil. Once the thermometer reaches 180 F, let the soil bake an additional 30 minutes. Take it out to cool.

4. Mix the cooled soil with equal parts perlite or coarse builder's sand and peat moss.

Solarizing Method

1. Shovel soil into a wheelbarrow for a larger batch that keeps the dirt out of the kitchen. Smooth and add soil until you have a 2- to 3-inch layer across the entire bottom and sides of the wheelbarrow. Make sure the soil is smoothed out flat.

2. Cover the wheelbarrow with clear plastic sheeting. Secure with garden twine if the day is windy.

3. Roll the wheelbarrow into an area that receives full sun. Let is sit for at least eight hours, raising the plastic and turning the soil every two to three hours.

4. Add equal amounts of perlite or coarse sand and peat moss to the wheelbarrow. Mix well with a shovel.

Tips & Warnings

• You can also make potting soil in the microwave. Place 2 pounds of soil in a poultry baking bag. Loosely twist and close the bag...you do not want to seal the bag to tightly because it could explode. Heat on high for 2 1/2 minutes. Be careful removing this from the microwave. Allow the soil to cool uncovered. Clean the microwave well.

• Potting mixtures can be specially mixed according to a plant's needs.

• Open your windows and turn on your exhaust fan when baking soil in the kitchen. The smell is not pleasant.

References

• Oregon State University Extension: Make Your Own Potting Soil
• University of Illinois Extension: This Land - Solarize Your Soil

Resources

• University of Florida Extension: Homemade Potting Soil Recipes