All potting soil has two main types of ingredients: something to hold moisture and something to create air pockets. The most common ingredient used to help soil retain moisture is peat moss. The ingredient that creates tiny air pockets and prevents compaction is perlite.
Add one heaping tablespoon of lime. The lime balances out the acidity of the peat moss, making the mix suitable for a wide range of plants. Mix the ingredients together until well blended.
The final step in the recipe is to add a couple heaping tablespoons of fertilizer to the mix. House plants and established seedlings do best with a slow-release fertilizer like 10-10-10. When planting seedlings, replace the 10-10-10 with seed starter fertilizer. Mix the ingredients together until well blended.