When gardening with containers or pots, never just use actual soil or dirt. You’ll need to use a good “potting mix” (also called potting soil) for proper drainage and aeration. What is potting soil and how can you make your own?
Container gardens are on my mind as the winter chill sets in. Containers are great for a number of reasons, namely that they’re versatile, space-saving, and allow you to be more efficient in your use of resources. If you have a small garden space or live in an apartment with a balcony or rooftop, containers are for you.
What is Potting Soil?
For containers, you’ll often ready that you need to buy or make “good potting soil.” But what does this mean?
Soil in pots needs to be able to provide anchorage for roots but also be light enough to allow air and water to the roots. Therefore, potting soil is lighter and fluffier than ground soil to provide the space needed for air circulation, good drainage, and healthy root growth. These soilless are sterile, so there is no chance of introducing pest or disease problems.
Potting soil can certainly be bought in bags at a garden stores. Look for “Soilless Potting Mix” which generally includes three ingredients: 1) peat moss or coconut coir for moisture and nutrient retention, 2) pine bark for anchorage, and 3) either perlite or vermiculite so air space so it’s light and fluffy.
Some potting mix also includes fertilizer or moisture-retaining treatments. If you use a potting soil with fertilizer, you’ll need to adjust the fertilizer you provide. (Think of salted butter versus unsalted butter in a recipe!)
Again, do NOT buy garden soil. Soil is often heavy and includes sand, clay, and other cheaper additives that won’t work for containers.
That said, many gardeners who plant a LOT of containers will mix up their own potting mixes!
How to Make Your Own Potting Soil Mix
For the amount of containers I use in my garden, I learned long ago that it’s much cheaper to make my own potting soil and store it in an old trash can, rather than pay for several big sacks of pre-made potting mix. Plus, I can customize the mix for a variety of different plants.
Before we go any further, note that if you only need a few small containers’ worth of potting soil, you may actually be better off buying a pre-made mix! Making your own is usually only economical on a large scale or in the long term.
Here are a few things to keep in mind before creating your own mix:
Again, when it comes to any potting mix, the lighter it is, the better. Loose and porous mixtures not only make a container lighter to move, but they transport water, fertilizer, and air to plant roots more quickly, and allow for good drainage, which is important for container gardening.
Start with the basic recipe below and then add soil sulfur to lower the pH or lime to raise the pH, according to the needs of your plants. Both additives can typically be found at garden centers. Plants such as lettuce, Russian sage, and marigolds prefer sweet soil with a pH of about 7.5, while others are acid lovers, like ferns, asters, and strawberries. They need a pH of about 5.5 to 6.0. Here’s a list of more plants’ pH preferences.
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 or coconut coir.