How to Use Potting Soil for Seedlings


The most exciting part of growing plants from seeds is when the seedlings finally break through the top of the soil. Shortly after that, when the seedlings have their first set of leaves, it will be time to transplant. The medium in which your seeds germinated does not contain the nutrients required for the growing seedlings, so they will need to be transplanted into a larger container with new soil. Some potting soils on the market are mixed with amendments such as perlite, vermiculite and peat moss. Check the label of the bag before adding any more amendments to the soil. If what you have is plain potting soil, it will need to be amended before planting your seedlings. Then the mixture will need to be sanitized and stored in a covered container until you are ready to use it.

Step 1

Amend the potting soil if required. Because the pot for your seedling is so small, it's best to mix the soil in a larger pot with drainage holes in the bottom. Pour the potting soil into the larger pot until half full. Add equal parts of compost, peat moss and vermiculite, and mix the soil well.

Step 2

Sterilize the potting soil by placing it in a large plastic bowl and moistening it with water. Make sure that the soil is very moist, or it may catch on fire. Cover the bowl loosely and place it in the microwave oven. Heat the soil for eight to twelve minutes; when you see steam, it is time to turn off the oven. Tighten the cover on the bowl and allow the soil to sit for 15 minutes. Carefully remove the lid and allow the soil to completely cool before working with it.

Step 3

Pour the soil into your seedling pots, almost, but not quite, to the top. Water the soil well, stirring, to ensure even moisture. Allow the water to drain from the bottom of the pot.

Step 4

Transplant your seedlings into the seedling pots, tamping the soil around the base of each seedling to make sure it has adequate contact with the soil.

Step 5

Fill a tray with water and liquid fertilizer, according to package directions. Place the seedling pots into the solution until that have soaked up enough of the solution that you will see liquid at the top of the soil. Remove the plants from the tray.

Tips and Warnings

  • Potting soil emits a foul odor while being sterlized, so make sure you provide adequate ventilation.

Things You'll Need

  • Large planting pot
  • Potting soil
  • Compost
  • Peat moss
  • Vermiculite
  • Large plastic bowl with a lid
  • Water
  • Planting pots, small seedling-size
  • Large tray
  • Fertilizer, liquid all- purpose


  • Texas A&M University
  • University of Minnesota

Who Can Help

  • University of Arizona
Keywords: potting soil for seedlings, amending potting soil, sterlizing potting soil

About this Author

Victoria Hunter, a former broadcaster and real estate agent, has provided audio and written services to both small businesses and large corporations. Hunter is a freelance writer specializing in the real estate industry. She devotes her spare time to her other passions: gardening and cooking. Hunter holds a Bachelor of Arts in English/creative writing.