People often use the terms ‘garden soil’ and ‘potting mix’ interchangeably. All plants grow in soil, so it shouldn’t matter what we call it, right?
It turns out that there’s more than one difference between these two growing mediums. To avoid any confusion when it comes to garden soil vs. potting mix, we gathered as much information as we could about each type.
Take a look.
What’s the Difference Between Garden Soil and Potting Mix?
Here’s a close look at each type of medium.
Garden Soil
Garden soil is the top 2 to 10 inches of uppermost soil, known as topsoil, with some organic matter added in. This organic add-in can range from bark shredding and peat to fertilizer and compost, depending on how you plan to use it.
It tends to be dense, heavy, and full of nutrients that are beneficial to outdoor plant health, which is precisely what outdoor plants need. Another reason it’s recommended for outdoor use is that it does a great job of retaining moisture.
However, garden soil is suitable for increasing the amount of healthy soil in your garden. Yet, it’s no substitute for compost or any other type of fertilizer that provides plants with the right balance of nutrients and minerals to grow and develop at a healthy rate.
Potting Mix
On the other end of the spectrum, you have the illustrious potting mix, which, in fact, isn’t soil at all. It’s technically a mixture of soil-less ingredients brought together to create this light, airy medium for your plants to grow.
Yet, keep in mind that they lack the mineral base of garden soil. So, they’re not as fertile or rich in nutrients.
What they are, however, is incredibly well draining. They’re also terrific at providing plants with plenty of aeration to keep the root system happy.
Some of these soil-less ingredients include:
- Peat
- Perlite
- Coconut coir
- Vermiculite
- Compost
- sand
When Is It Better to Use Garden Soil?
One of the features of garden soil is that it already contains a significant amount of organic matter. As a result, it’s best used in the garden wherever you need to add nutrient-rich soil to your yard.
Some of the best uses for garden soil include:
- Around and under rose bushes
- At the base of ornamental shrubs
- In outdoor planters
- In vegetable plots
- In raised flower beds
When Not to Use Garden Soil
While adding garden soil to your garden will do wonders for your plants, you still need to supplement it with fertilizer or compost several times a year to ensure your plants stay healthy and strong.
Another thing is that you should avoid using garden soil with your potted indoor plants at all costs.
Garden soil simply doesn’t have the structure or nutrient content needed to support potted plants. It’s also super dense. Thus, the soil becomes too dense and heavy for the roots, and they can’t get the nutrients or oxygen they need to survive.
When Is It Better to Use a Potting Mix?
Potting mixes are made with potted plants in mind. They’re almost exclusively used with indoor plants, but you can also add them to outdoor container plants to ensure that the soil remains well-aerated and boost drainage.
Two plants that do well in potting mixes are succulents and cacti. These drought-tolerant plants have specific needs when it comes to their growing mediums.
When Not to Use Potting Mix
Just as garden soil has certain factors that make it ill-suited for use with indoor plants, avoid using potting mixes in outdoor garden beds.
They don’t have what it takes to support outdoor plants as well as withstand the taxing demands of the elements.
What’s Potting Soil?
Potting soil fits somewhere between garden soil and potting mix. It contains dirt and is often labeled for ‘in-ground use’ and has many similar features as garden soil.
Yet, potting soil takes it a step further. It contains several soil-less ingredients, just as is the case with potting mix.
These ingredients include peat moss, which helps retain moisture in limited amounts and perlite to provide air pockets in the soil and help keep it light and fluffy. Another vital component is coarse builders’ sand for providing proper aeration and drainage.
Combining dirt with these soil-less add-ins helps formulates something as close as possible to top-quality soils found naturally in the ground.
Is There a Difference Between Potting Soil and Potting Mix?
Yes, potting soil and potting mix are two completely different growing mediums.
The former is made of ground dirt, making it soil-based even though it has some soil-less ingredients added to it to boost its nutrient content.
Potting soil is perfect for outdoor plants that require dense, compact growing mediums to thrive. You can use it to raise flower beds or anywhere that needs a bit of extra nutrient-rich soil.
On the other hand, potting mix is completely soil-less. It has no amounts of dirt or soil at all, but only organic soil-free ingredients. That’s why it’s ideal for potted plants that need a light, airy medium to grow.
What Is a Good Potting Soil Ratio?
When you buy potting soil, you’ll notice that it contains various components that work together to provide your plants with the best nutrients.
If you have the time and energy, you can even make your own DIY potting soil using the ratio below.
For large gardens, you’ll need to start with one gallon of each ingredient, which you can buy online or from your local garden center. If you prefer to make a smaller amount, you can always use half gallons, which comes to about 2 quarts, or 8 cups, until you get the perfect mix for your plants.
Here’s a quick look at the ratio of potting soil:
- 1 part mature compost, peat moss, or coir
- 1 part topsoil or garden loam
- 0.5 parts perlite, vermiculite, or coarse sand
- 2 cups pelleted slow-release fertilizer
Other soil guides
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How to Turn Garden Soil into a Potting Mix?
Turning garden soil into a potting mix means you’ll need a few extra ingredients to balance out the ratio between soil-based and soil-less ingredients.
The best way to do that is to use a 1:1:1:1 ratio where garden soil makes up only a quarter of the finished growing medium. The three remaining elements should be 1 part compost or aged composted manure, 1 part peat moss or coir, and 1 part perlite.
Related reads: How to Prepare and Make Healthy Gardening Soil
What Are the Ingredients Required for the Best Potting Mix?
An ideal potting mix should be able to hold the right amount of nutrients and moisture around the plant’s root system. At the same time, it should be fluffy and easy to maneuver to allow the roots to access oxygen, thus effectively reducing the chance of root rot.
Below are ingredients commonly found in standard potting mixes:
- Peat moss, or sphagnum peat moss: retains moisture and nutrients
- Coir: lightweight fiber often used as a more eco-friendly alternative to peat
- Perlite: provides aeration and increases the roots’ access to oxygen
- Vermiculite: similar to perlite in composition, it also provides aeration for potted plants
- Pine bark: provides the plant with anchorage and aeration
- Coarse sand: supports and anchors the plant, and provides proper drainage
- Compost: provides key nutrients not naturally found in potting mixes
How to Make the Best Potting Mix?
Making homemade potting mix is definitely more time-consuming than just buying a bag from a garden store. Yet, buying a top-quality bagged potting mix means factoring in the price of ingredients, packaging, and transportation.
So, you can save money when you buy each ingredient separately and mix them at home to create the best potting mix to suit your plants’ growing needs.
Here’s a recipe for making a standard potting mix for a few small planters. If you have larger containers, use a 1-gallon, or 16 cups, bucket instead.
- First, gather your ingredients:
- 1 cup perlite
- 1 cup peat moss
- 2 parts compost
- Next, mix everything using a hand fork or a trowel.
- Check the pH levels of the potting mix to ensure it’s in the slightly acidic range between 6.0 and 7.0.
- Use immediately or store the potting mix in airtight containers.
FAQs
Should I Combine Garden Soil and Potting Mix?
Not necessarily. You should only combine the two if you have extra amounts of garden soil and you want to add some organic matter to your potting mix.
When Should I Refresh the Potting Mix in my Planters?
The general rule is that you should change the soil in potted plants every 12–18 months.
What Are the Main Ingredients of Soil?
According to the Soil Science Society of America, soil is a combination of dead and living organic materials, minerals, water, and air. These components react with each other to provide us with a highly resourceful, potent, and vital natural resource.
How Long Can I Store Growing Mediums?
You can store unopened and unused bags of any type of soil or potting mix for up to a couple of years before it goes bad. However, opened bags can only retain their quality for up to 12 months as long as they’re stored in dry, cool airtight containers.
Final Thoughts
This garden soil vs. potting mix rundown highlights the main differences between these two potting mediums. When choosing one over the other, remember their uses along with their benefits and drawbacks.
Knowing which type works best with which plants can help you determine the right place for each one. This way, you’ll keep your plants happy and healthy, both indoors and out.