How to Make Potting Soils


Whether you are preparing for spring seed starting or just want to plant a few containers of flowers or herbs, potting soil is a necessary element. Purchasing all your potting soil can get expensive, especially if you have a lot of planting to do. Making your own sterilized potting soil is cheaper and requires minimal effort. And you can be sure it's sterile and weed-free. Make your own mix two or three weeks in advance of needing it, so it is ready come planting time.

Step 1

Fill a roaster pan with a 3- to 5-inch layer of compost, either store-bought or from your own compost heap.

Step 2

Cover the roaster pan with aluminum foil, and place a food thermometer through the foil and into the compost.

Step 3

Place the pan in a preheated 250-degree Fahrenheit oven. Check every ten minutes until the thermometer reaches 180 degrees, then let cook for 30 minutes.

Step 4

Mix 1 part of your sterilized compost, 1 part sand and 1 part peat moss. Break up any large clumps while mixing, and combine thoroughly.

Step 5

Store in 5-gallon buckets until the potting soil is needed. Place the lids on each bucket securely so the soil mix remains sterilized.

Tips and Warnings

  • Do not use compost that still has large pieces of material that haven't broken down. Avoid baking the compost for longer than 30 minutes after it reaches the desired temperature. Too much heat will cause the nutrients in the soil to break down.

Things You'll Need

  • Compost
  • Roasting pan
  • Foil
  • Oven thermometer
  • Peat moss
  • Sand
  • Buckets with lids


  • Oregon State University
  • University of Arkansas Extension
Keywords: homemade potting soil, garden soil mixes, sterilizing compost

About this Author

Jenny Harrington has been a freelance writer since 2006. Her published articles have appeared in various print and online publications. Previously, she owned her own business, selling handmade items online, wholesale and at crafts fairs. Harrington's specialties include small business information, crafting, decorating and gardening.