Container Gardening – DIY Potting Mix

The words dirt and soil are not interchangeable. Simply put, dirt is dead. It does not contain the beneficial living organisms that make up soil. Soil is the very thing that gives life to the plants we grow and the food we eat. When gardening at home, it is important to have some healthy soil on hand, which can either come from your own compost or be purchased from your local garden store. You can also find potting mixes that are great for gardening in containers. Read below to learn about the components of a healthy potting mix, how to make your own, and why it may be beneficial to use a homemade mix.  

We’ll start with that last piece because you are no doubt wondering why in the world anyone would want to create a mix when they can buy one at the store! For one, you’ll save money. At your local garden store, you get what you pay for—a high quality bagged mix will be expensive. The cost of ingredients, packaging, and transportation all adds up to the price of the bagged mix. It also can be satisfying to successfully grow something from a homemade mix! 

Before we get carried away with the physical materials you’ll need, we should keep some things in mind. An ideal mix should hold moisture and nutrients around your plant’s roots, which is critical for optimal plant growth. This mix should also be light and airy, making it easy to maneuver, allowing plants to take root and access oxygen effectively, and reducing the chance of rot. An effective potting mix should also provide structure for your plants. It’s a good idea to know your plants needs’—such as nutrients and water—before creating your mix.  

Now, let’s explore the common ingredients found in a standard mix: 

Sand provides anchorage and aeration to a potted plant, adding weight to support the plant. It is used as a cheap filler in commercial bags and is unnecessary unless planting cacti or succulents. Sand can be a great addition for potted plants that are top-heavy to prevent from tipping over. 

Compost and worm castings both provide key nutrients. You can create your own compost by using a worm bin for your food scraps or collecting your yard debris into a pile. For more information on composting at home, check out our composting topic in our Container Gardening Series. 

Pine bark comes from paper mills and provides anchorage and aeration to a potted plant. Look for fineground bark to use in your mix. The thicker variety can be used as mulch. 

Sphagnum moss (and peat moss) comes from peat bogs in the northern U.S. and Canada. Sphagnum moss is a living plant species, while peat is the partially decomposed remains scraped from the top of the bogs. Peat provides moisture and nutrient retention, though is highly acidic. Pair with perlite while potting for aeration. 

Coir is the byproduct of the coconut processing industry. This lightweight fiber is often a sustainable substitute for peat. Coir holds water within the potted mix. Coir is often found in compressed blocks that expand when wet. 

Perlite is a volcanic rock created from exposure to high temperatures. Often mistaken for Styrofoam, perlite is lightweight, provides aeration, and is also acidic. Be sure wet down before mixing in order to not inhale the dust it creates. 

Vermiculite is also volcanic in origin. It is a mineral that expands when exposed to high temperatures. It is lightweight and provides aeration to a potted plant. 

These components are commonly found in both homemade and retail mixes. Your mix does not have to include every one of these—one size does not fit all. Specialize your mix to the needs of your plants. Each ingredient plays a specific role in the health of our plants. 

Common Recipes 

For a potting mix: 

  • 1 part peat moss 
  • 1 part perlite 
  • 2 parts compost

For seed-starting: 

  • 2 parts compost
  • 2 parts peat moss
  • 1 part perlite or vermiculite 

Note: a “part” can be a one-cup measuring device that would make enough potting mix for a few small containers, or it can be a 5-gallon bucket to make enough potting mix for larger containers or raised beds. If using a large measuring device such as a 5-gallon bucket, I recommend using a tarp to mix your ingredients. You can easily lift the corners of the tarp to mix. Your mix can then be stored in an airtight container for later use. 

Be sure to check the pH of your potting mix when finished mixing. Most plants require a 6.0-7.0 pH for healthy growth. You can find affordable soil test kits online or at your local garden store. 

A recommended supply kit for every DIY-er: 

  • A hand fork
  • A trowel 
  • Garden gloves 
  • Large bin(s) with handles and a lid (this is what you will store your potting mix in) 
  • A measuring device 
  • A particulate mask 
  • Protective eyewear
  • A tarp, optional

Frequently Asked Questions 

Where can I buy these items? You can find these items at your local garden store or in bulk online. 

What is the difference between soil and dirt? Soil is alive and full of beneficial microorganisms and decaying organic matter. Dirt is displaced soil made up of sand, silt, and clay and lacks in structure and the beneficial nutrients found in its counterpart. Bring your dirt to life by mixing it with the living organisms that make soil, soil. 

I have a large bed to fill. How do you suggest I mix a large batch of soil? Use a tarp and a 5-gallon bucket. Use the 5-gallon bucket to measure your ingredients, and dump onto tarp. Lift all four corners of tarp to mix all together. 

Where can I get my soil tested? Do you do that at the Garden? The UF/IFAS Extension Soil Testing Lab can analyze your soil. Contact your County Extension Agent for complete info. For Collier County:; 239.252.4800. For Lee County:; 239.533.7500.