Making your own potting soil allows you to better cater to the needs of your plants. The results are more stable and consistent.

Until 30 years ago, most gardeners made their own potting soil by combining their best garden soil with rotted manure from the barn or buckets of leaf mold hauled home from damp stream banks, topped off with a dusting of wood ashes. Contrast and compare: North American gardeners now spend more than $500 million each year on potting mixes and specialty soils.

We've all done it...... we buy big bags of potting soil in the spring. And we know it's not the best thing we can use, but plants gotta get planted. A lot of us stock up on bags of  stuff like Miracle Gro potting soil. We know that It’s just a high-priced mix of peat moss and synthetic chemicals, like many others. But it's convenient. And we know that Miracle Gro was also closely associated with the now defunct chemical and GMO Frankenstein, Monsanto.  And we know that ordinary garden soil is not recommended as a potting mix. It’s usually too heavy and may contain weed seeds, diseases, and insect pests.

Making your own is usually only economical on a large scale or in the long term. I have too many containers and raised beds to make buying the stuff very wise. You can actually buy inexpensive bags of potting soil and add components to create your personalized mix.

The following DIY potting soil recipes use a combination of  ingredients. There are lots of good recipes for potting soil, find one that works well for you.

Some plants love soil to retain moisture, while others need great drainage. At different times in the growing cycle, plants need different nutrients. This is why there are different potting soil combinations available

Granular fertilizer is not included in these mixes because the best fertilizers I have found are epsom salts and liquid fish emulsion, which should be watered in every 2 weeks during the growing season. I find the fertilizers in mixes not good enough for my plants' needs, and doesn't last as long as adding it on a schedule. Some plants HATE fertilizer, so why put it in your all-purpose potting soil?

Following is an array of different recipes for potting soil mixes. Experiment to find your favorite.

Easiest

Foliage Plants

• 2 parts peat; 1 part perlite; 1 part coarse sand

OR

• 1 part peat; 1 part pine bark; 1 part coarse sand

Succulents

• 2 parts soil; 1 part peat moss; 1 part perlite; 1 part coarse sand

Bromeliads

• 1 part peat; 1 part bark; 1 part coarse sand

Seedlings

• 2 parts compost; 2 parts peat moss; 1 part vermiculite (pre-wet)

Soil-Based Mix

This mix is heavier than peat-based mixes, but it has good drainage. Vermiculite or perlite can be used for sand.

• 1/3 compost; 1/3 topsoil; 1/3 sand

Typical Ingredients

Peat Moss or Coconut Coir

• for holding moisture & adding bulk and airiness

Peat Moss. A farmed, organic material that holds moisture and makes up 80% of most store bought potting mixes is from Canadian bogs  and is being over farmed and distributed. Peat Moss takes THOUSANDS of years to form. Therefore even though technically it is a renewable resource, our demand for it has far exceeded the rate at which it forms.

I personally use peat moss, because i think it's  superior to Coconut Coir (which dries out too fast). Gardeners are now encouraged to switch from Peat to Coco because of the environmental impact of over harvesting peat to the point of near depletion. Coconut Coir on the other hand, is inexpensive to produce, is truly renewable and works very well.  BUT environmentally, it is not so hot as a substitute. It has to travel from it’s #1 producing country, Sri Lanka. That's a lot of fuel.

Lime

• for pH balance.

If you’re using peat moss (which has an acidic pH) you’ll need to add a bit of lime to it to offset the acidity. Unless you're making the mix for acid-loving plants and citrus trees. If so, skip the lime in your mix.

Perlite

• For improved drainage and water retention.

Perlite is volcanic rock.  It’s heated until it bursts into a styrofoam-like ball.

 Native Garden Soil

Bagged Garden Soil

Clean garden soil sold in bags can be used for the soil part of your potting mix, rather than use your garden soil, which is not very sterile or clean (as much as we'd like to think so).

This is topsoil, enriched with compost and other organic matter so it’s nutritious for plants. It has a heavier texture and holds water longer than potting mixes. It’s more affordable than potting soil because it doesn’t have pricier ingredients like perlite, vermiculite or moss. It’s mostly soil, and soil is cheap.

Compost

• For nutrients, water retention, and beneficial microbes.

Pine Bark - Peat moss substitute

Pine bark creates a light potting mix with air space but low water holding capability. It degrades slowly and is a good component for mixes for potted ornamentals. If the pine bark is ground fine enough, it may be partially substituted for peat moss. Make sure that it has gone through the aging process before use.

For 20 gallons of soil - What you'll need:

20 gallon plastic tote bin with lid to store your mix.

• 1.5 buckets of peat moss
• 1/4 cup lime
• 1 bucket perlite
• 1/2 bucket any garden or topsoil
• 1 bucket compost

Use a big, basic metal bucket and measure 40 cups of water into it. 
MARK THE BUCKET WITH A LINE on the inside and the outside at the 40 cup line. This is your 10 quart mark for future measurement.

Classic Soil-Based Mix
Very easy.... equal parts of ingredients

1 part garden loam or topsoil

1 part clean builder’s sand or perlite

The organic material in the above mix provides structure and the sand will improve drainage.

Add supplemental fertilizing if and when your plants need it. Use fertilizers that cater to particular needs, like acid-loving.

succulents and cactus

1 part perlite

1 part vermiculite

2 parts coarse sand

Classic Homemade Small Batch Potting Soil II

-Multiply amounts, as needed

Homemade Potting Soil Recipe

• Compost – 6 cups
• Pulverized Top Soil – 6 cups
• Worm Castings – 2 cups
• Spent Coffee Grounds – 2 cups
• Perlite – 2 cups

Components:

Compost is a must in creating great potting soil. Not only is it lightweight, it’s filled with an incredible balance of nutrients as well. Nutrients that are released slowly to the roots of plants over time. Compost will also absorb and retain water in massive amounts. In fact, it can absorb 10 to 15 times its own weight in water.

Pulverized top soil is simply loose dirt / soil. You can often find it bagged, or in bulk. You can substitute with bagged garden soil.

Worm Castings

They provide an incredible balance of slow-release nutrients to plants. All while keeping the soil lightweight and absorbing water.

Coffee Grounds

Coffee grounds are one of the most powerful, humus-building organic ingredients around. Much like worm castings, they help to add all-important structure to potting soil. And they also contain a fair amount of trace nitrogen, which is extremely important for it’s fertilizing capabilities.

Perlite

It it’s natural state, perlite is 100% all-natural volcanic glass. But when heated, it pops open almost like popcorn. When used as an ingredient in potting soil, perlite not only helps to improve drainage, but keeps the soil mix light. Like compost, perlite can keep moisture around the roots of potted plants, releasing it back out as the soil dries out. Perlite, with a neutral PH of 7, won’t affect the make-up of the potting soil. It is the perfect soil-lightening additive.

Although purchasing the base ingredients and developing your own mix may not result in a cheaper mix, it does offer the opportunity to be creative and to modify mixes for specific goals or plants that you feel would make a media better for your situation.

Either soil-based or peat-based potting media can be made at home by combining individual ingredients.

Recipes given here are measured in gallons for primary ingredients and in teaspoons and tablespoons or ounces and grams for smaller ingredients. Primary ingredients used for both soil-based and peat-based media are discussed below.

• Sphagnum peat moss has a course texture and contributes to good aeration, yet provides waterholding capacity to prevent soil from drying too quickly. Adding too much sphagnum peat, however, can restrict soil drainage by holding too much water. Sphagnum peat moss can be difficult to wet and should be moistened prior to mixing in other ingredients.
• Coarse, sharp, or builder sand, often used in construction, is a primary ingredient in potting media. Like peat moss, sand improves drainage and aeration, but does not improve water-holding capacity. Too much sand will make containers too heavy to move. Sand should not be mixed with a clay-based soil.
• Perlite can be used in both peat-based and soil-based potting media in place of sand. Perlite is expanded volcanic rock (fluoride-based), manufactured when heated to 1,800°F. Like sand, perlite provides great drainage, but is lighter in weight and holds more air. Although more expensive than sand, the advantages may outweigh the additional cost. Disadvantages of perlite include: 1) a tendency to float to the top of the medium when watered; 2) an inability to hold or retain water; and 3) a need to be moistened before it is mixed into other ingredients to reduce dust, which is harmful if inhaled.
• Vermiculite is often used instead of perlite. Vermiculite is clay belonging to the mica family and is naturally found in laminated flakes. It expands when folds of vermiculite can hold water, nutrients, and air, unlike perlite. Only horticultural grades, sold at garden centers, are recommended. Vermiculite can easily compact, which reduces its ability to hold water and air.

Making Soil-based Potting Media

The following is a basic recipe for soil-based potting media. In this recipe garden loam soil, coarse construction sand, and sphagnum peat moss are combined together in equal parts by volume:

Add one gallon of moist, coarse sphagnum peat moss, followed by one gallon of coarse sand, perlite, or vermiculite.

Adjust the texture of the medium to create a loose, well-drained mixture. Sand feels gritty and clay feels sticky. If the potting soil feels too sandy, more peat moss should be added. If the potting soil feels too sticky, extra sand and peat moss should be added. Adjust the texture by adding small portions of sand and/or peat moss until you are satisfied with the texture.

you can adjust and change your mix as you see fit for your needs and situations. Keep in mind that not all bulk materials are created equal. If you choose to use a locally available source of compost or other alternative materials in your mix, you should then be aware of their nutrient contents and cleanliness. Both factors will affect the success of your plants and experimenting may result in media you consider better than commercially available media, or it may result in poor plant health and death.

Here are a few things to keep in mind before creating your own mix:

If rapid drainage is needed, as is the case for cacti, succulents, and lavender, add extra sand and perlite.

If greater moisture retention is needed, as is the case for ferns and woodland flowers (like primrose) add extra vermiculite

Cornell Univerity Organic Soilless Mix

Don't ask me how to convert cubic anything to feet or yards. I'm sure there's an online conversion chart.
I don't see much in the way of exactly how much potting mix this all makes.

1/2 cubic yard perlite

10 lbs. bone meal

5 lbs. ground limestone

5 lbs. blood meal

The Old Farmer's Almanac
Penn State Extension
Cornell University

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