How to Make Seed Starting Potting Soil


Starting seeds indoors gives a gardener an advantageous head start to the planting season. With tender care, you can coax tiny seeds to germinate under artificial lights while the temperatures are still frosty outdoors. As you prepare to start seeds, make sure your planting materials are high quality to ensure planting and growing success. Make seed starting potting soil by mixing several different planting mediums together to create a light and rich medium.

Step 1

Pour the compost into the oven dish, and spread it out evenly. Insert the probe of the thermometer into the center of the compost, and cover the compost with aluminum foil.

Step 2

Preheat the oven to 250 degrees F, and place the compost into the oven. Watch the temperature as it rises. When the temperature of the compost rises to 180 degrees F, start timing the baking process. Leave the compost in the oven for 30 minutes at a minimum of 180 degrees F.

Step 3

Remove the compost from the oven and allow it to cool.

Step 4

Pour the cooled compost into the bucket. Add equal parts of coarse sand and peat moss. Mix the three ingredients well with your hands to incorporate them completely.

Tips and Warnings

  • The smell from the baking compost may be undesirable to some people. Opening a window can help dispel some of the odors.

Things You'll Need

  • Aged compost
  • Large, shallow oven dish (3 inches deep)
  • Aluminum foil
  • Instant-read thermometer (with probe)
  • Coarse sand
  • Peat moss
  • Large bucket


  • Washington State University: Seed Starting
Keywords: starting seeds indoors, start seeds, starting potting soil

About this Author

Kathryn Hatter is a 42-year-old veteran homeschool educator and regular contributor to Natural News. She is an accomplished gardener, seamstress, quilter, painter, cook, decorator, digital graphics creator and she enjoys technical and computer gadgets. She began writing for Internet publications in 2007. She is interested in natural health and hopes to continue her formal education in the health field (nursing) when family commitments will allow.