There are a couple of good reasons for making your own potting soil. The most obvious is that blending your own ingredients together is cheaper than buying commercially made sterile varieties.
In addition, different plants require different soil types for healthy and productive growth. Thus, you can customize your potting soil mix to meet the needs of the plants you want to grow.
Let’s start with a basic mix that contains equal parts of peat moss, perlite OR vermiculite, compost and garden soil. The ingredients will easily blend together if you add some moisture before mixing.
Garden lime, soybean or kelp meals, and rock phosphate can be added to provide additional nutrients that can feed a plant for up to a year. If you choose to include these, add a handful of each.
If you research basic potting soil recipes, you will find some variations. It really is often a matter of personal preference. You can make potting soil using a mixture of 25 percent perlite, 25 percent compost and 50 percent peat moss.
Another option is to mix sphagnum peat moss and vermiculite in equal amounts. Add five pounds of ground limestone, which is available at most gardening and hardware stores, for each cubic yard of the potting soil mix.
A basic potting soil mix for plant seedlings can be made by mixing two parts each of compost and peat moss. Add one part vermiculite or perlite. The vermiculite should be moistened before adding it to the potting soil mix.
A good soil recipe for annuals is a combination of one part each of coarse sand, composted pine bark, worm casing, composted manure and expanded slate, which is produced my heating the slate many times to expand its original volume so that it becomes a good lightweight aggregate.
The worm casings and the manure used in the recipe above provide vital nutrients and can eliminate or vastly reduce the need for extra feeding or fertilizing.
You can mix the ingredients in a wheelbarrow or garden cart. One means is to simply place the peat moss, perlite, compost and garden soil into the container and use a hoe to thoroughly mix the ingredients. Use the hoe to rake everything in one direction. When the mix is all in the front of the wheelbarrow, repeat the process and rake it to the back of the container. Repeat as often as necessary until all ingredients are well blended.
You can also mix the ingredients in just about any large container. Running the mix through a one-quarter inch screen helps remove unwanted lumps from the potting soil mixture.
If making potting soil seems like a big job, think on a larger scale and make enough for a year or two at a time. Your homemade potting soil mixtures can easily be stored by placing the blended mix in a plastic trash bag or a bucket and set it aside for later use.
Want more information about making your own potting soils?
Organic Gardening Magazine has compiled a list for a variety of potting soil recipes.
Visit the University of Illinois Extension’s Illinois Vegetable Garden Guide for information concerning the preparation and care of soil.
Learn more about Organic Potting Mix Basics for basic information on organic potting mixes.