A DIY Potting Mix Recipe for Container Gardening
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.
Basic Container Potting Mix Recipe
Ingredients
1 bucket (10 quarts) coconut coir
1/2 bucket (5 quarts) perlite
1/2 bucket (5 quarts) vermiculite
1/2 bucket (5 quarts) screened compost or composted cow manure
2 cups fine sand
2 cups pelleted time-release fertilizer
Instructions
Mix thoroughly. Makes enough to fill two 14-inch tubs or five 12-inch hanging baskets. Double or triple recipe for bigger containers.
How Much Potting Mix Do I Need?
Potting mix is sold by volume (typically measured in quarts), and most pots are measured by their diameter. To translate quarts of mix into various pot sizes, use this quick reference.
Pots & Tubs |
|
|---|---|
| Container Size | Amount Needed |
| 8-inch | 3 quarts |
| 10-inch | 6 quarts |
| 12-inch | 8 quarts |
| 14-inch | 12 quarts |
| 16-inch | 20 quarts |
| 20-inch | 24 quarts |
| 24-inch | 28 quarts |
| 30-inch | 72 quarts |
| 36-inch | 96 quarts |
Hanging Baskets |
|
| 12-inch | 6 quarts |
| 16-inch | 10 quarts |
Window Boxes |
|
| 24 inches by 6 inches | 12 quarts |
| 36 inches by 6 inches | 20 quarts |
Learn More
Wondering when and how to fertilize your containers? Here are some tips.
See our Plant Growing Guides for advice on planting and growing popular vegetables, fruit, and flowers!
Do you make your own potting soil? Share your recipe in the comments below!
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My recipe for soil includes screened mulch, egg shells, coffee grounds, fireplace ashes and finely shredded paper mixed in a 50 gal drum
Please inform your readers of the negative environmental effects of peat moss and promote sustainable alternatives instead, like coconut coir.
Peat moss takes tens of thousands of years to form in bogs, then is dug up and put in bags for gardeners in a matter of days. That natural wetland bog environment uses the peat to filter and purify water, and thousands of animal species live in bogs. Draining and digging them up for gardeners is unsustainable and bad for the environment. The bogs will never recover fast enough for more peat to be harvested in the same area, so new bogs must be destroyed all the time. Digging up peat bogs releases massive amounts of CO2 into the atmosphere and peat moss is often exported from poor countries to be shipped to rich countries at non fair-trade prices.
Peat bogs are even known to catch on fire when they are drained, and the peat can burn underground for months on end, releasing tons of smoke, CO2 and other hazardous chemicals into the air.
Consider buying compressed coconut coir online for adding organic matter to soil. Unlike peat moss, coconut coir is completely renewable (it's made from waste coconut shells), and is pH neutral (peat moss is acidic). It ships in small cardboard boxes, which is better for the environment than giant plastic bags filled with peat.
You have a responsibility to the Earth and your readers to be informed about these types of concerns.
No one sells real peat bog moss anymore, relax. Nearly everything sold in the us market as peat is simply composted lumber mill waste from canada. Yes it's a scam. But it's much less of a scam than pretending that mass monoculture coconut farms destroying jungle and shipping the discards 5,000 miles on diesel ships is carbon neutral.
I keep seeing things while looking for a good potting soil (long story short I got a bad bag and my house is full of fungus gnats that are so resilient I'm going to re-pot everything), about some soils being "hot" and that plants need to get used to it. Particularly brands like Fox Farm. I'm having trouble understand what it means that it's "hot" for plants, because I'm pretty sure they don't mean it's popular, people appear to be referring to temperature. How is a potting soil generating heat? I'm very confused.
You are correct that the term “hot soil” isn’t referring to the popularity nor the temperature; rather, it refers to the nutrient content of the soil. I don’t believe this usage is all that common, but it appears to mean soil that has a high nutrient content—even too high—which can actually be bad for plants.
Generally, any organic soil that’s meant for use in containers should do the trick. No need to get overly fancy!
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