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The Key Difference Between Potting Soil and Potting Mix

The Key Difference Between Potting Soil and Potting Mix

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As Bilbo Baggins explains The Fellowship of the Ring, “All hobbits share a love of things that grow.”

Maybe you were born with a green thumb, maybe you’re getting in touch with your inner hobbit, or maybe you too just “share a love of things that grow,” but whatever the reason, you’re intent on making sure your potted plants indoors and outdoors get the best soil possible.

That means taking a closer look at what actually makes up their soil in the first place. Setting aside the soil used to stimulate growth in The Shire (yes, J.R.R. Tolkien went that deep in explaining the lore of Middle Earth) the question of what makes up your plants’ soil is likely to come down to two basic components – potting soil and potting mix.

While they sound similar, however, the fact is that the two are quite distinct. Each offer their own benefits, and to give your plants the best shot at growing well, you’ll need to understand what each of them are, what they do, and how either or both can help you.

What Is Potting Soil?

Potting soil refers to any type of gardening container that has dirt. This is obviously very broad, which is what leads to the confusion with potting mix that, as we’ll see, is more narrowly defined.

Potting soil tends to be rich in nutrients because it is full of organic matter that is in the process of decaying as well as minerals, both of which can supply much-needed nutrients to your plants.

Potting soil can, thus, feature a huge range of different types of dirt, soil, and organic material from your garden, with any number of ingredients involved and the specifics varying from one soil sample to another.

What Is Potting Mix?

By contrast, potting mixes are specifically designed for maximizing the growth of specific plants. They do not contain regular dirt and soil and are far more specialized than potting soil.

The best potting soil tends to be very basic, though some can be rich in nutrients and materials such as vermiculite, bark, sphagnum, moss, and perlite.

Potting mix particles are typically larger than the granules you’ll find in regular potting soil. They do not clump together the same way and, thus, offer superior aeration.

As a result of these two facts and the lack of clumping, potting mix tends to be more lightweight than potting soil.

Customization is a big part of what distinguishes potting mix from potting soil. While the former is very broad, the latter is far more focused on formulating certain mixes for certain plants and, indeed, certain stages of growth at that.

Different plants will have different mixes that are formulated just for them.

A consequence of this, however, is that while potting soil can be more universally applied (albeit with varying results) for most types of plants, a potting mix that works wonders for one type of plant may be ineffective or even damaging to another plant.

The Pros and Cons of Potting Soil

If you’re the type of person who needs everything in your garden and life to be organic, you’ll want to opt for potting soil. It is completely organic with no artificial additives.

Different types of potting soil may have a wide range of different materials mixed in there, but rest assured, whether it’s dirt or fungi or any number of plant particulates, it’s all organic.

That’s definitely a plus if you are looking to create a more eco-friendly, all-natural garden. While potting mixes are formulated to meet certain plant needs, they are certainly artificial and manufactured.

For an all-natural garden, you’ll want to go green, and that means going organic.

There’s also the fact that potting soil is bound to last a long time. After all, dirt is pretty indestructible, and because it makes use of decaying organic material to sustain the plants in its midst, it is self-sustaining, which cannot be said of potting mix.

Unless the soil is severely disrupted by physical force or something drastic such as a flood or severe dry spell, a well-maintained patch of potting soil should remain good and fertile for a long time. You can help that fertility along in an all-natural fashion with an all-natural fertilizing manure.

However, there are a few negative factors you’ll need to be aware of.

For starters, potting soil can be problematic when placed in containers because the soil compacts and clumps together easily. This can lead to a lack of air circulation, which in turn can choke off air from the roots as well as lead to the plant becoming waterlogged.

In addition, potting soil isn’t always very light and fluffy, which is necessary for roots to grow out without being obstructed. You’ll need to find a way of compensating for this lack of soil fluffiness if you are going to get the most out of your roots and, thus, your plants.

Potting soil can also be quite dense, which can make it hard for seeds to germinate and start growing.

That said, potting soil is also pretty inexpensive. That might not sound like much considering the fact that it’s still, well, dirt, but one look at how expensive top tier potting mixes can make you appreciate its affordability a lot more.

If you are new to the gardening scene or are just looking to cut back on expenses for one or more of your potted plants, choosing potting soil over potting mix can be an easy way to do that.

The Pros and Cons of Potting Mix

One of the best things about potting mix is that it is optimized for each plant for which it is formulated.

With potting soil, you have a standard soil type and need to figure out how to best adapt that soil for use for any type of plant you choose to grow. That can be problematic if you are trying to grow different plants with different soil requirements.

With potting mix, it’s a lot easier, at least in theory. Simply get the appropriate potting mix for each type of plant you wish to grow, and voila.

The fluffy texture of potting mix also makes it a lot easier for seeds to start sprouting and roots to grow outward. This makes for a medium that is highly conducive to growing without the clumping or weight that can slow growth in potting soil.

That fluffier, more lightweight texture also means potting mix enjoys good aeration compared to potting mix, which means air can flow into the mixture and plants’ root system easier.

This also means that the plant is a lot easier to drain. Potting soil traps water, and while that can be useful for keeping soil moist for longer periods of time, it can also lead to flooding. By comparison, potting mixes are able to retain water well without this problem.

Even so, there is no denying that potting mixes can be a lot more costly than potting soil. The latter simply consists of organic material and dirt and is, thus, literally “dirt cheap.”

The special materials that make up each unique potting mix are far more expensive, and those costs are passed on to you.

You’ll have to decide whether the potential for easier or enhanced growth ability is worth the higher price.

The lightweight nature of potting mix can also be problematic. While it has all the positive attributes described above, it also means that plants are a lot more vulnerable to heavy winds, which can displace light potting mixes a lot easier than it can heavier potting soil.

This can be especially problematic if you plan to use your potting mix outside. As much as you might love an outdoor lawn and garden area, you can find this quickly, and all too easily, disrupted by gusts of wind spoiling your potting mixes.

What’s more, potting mix isn’t as all-natural as potting soil.

Finally, there’s the fact that the lightweight and fluffy nature of potting mix means it is more fragile and, thus, can break down over time. Eventually, it will reach a point where it will become unusable and need to be replaced.

How quickly this happens will depend on many factors, and you may be fine moving your plants from one potting mix to another.

However, it is worth noting that potting soil is made to last. While potting mix may offer faster short-term growth gains, potting soil can prove the better long-term solution for gardens over several plant generations.

Of course, distinctions such as those are matters of taste. Just as there is a dazzling array of diversity in the types of plants and gardens, there is just as great a range of motivations behind those gardens in the first place.

Your garden and gardening aims are unique.

Do your research, weigh the pros and cons, and celebrate your green thumb and “love of things that grow” by selecting the right potting soil or potting mix for your particular plants.

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Ray Henry

Thursday 28th of January 2021

Nice to have some practical commense advice :)

Willie Duncan

Friday 17th of April 2020

I make my own almond milk. Instead of throwing the pulp away, can I use it as a vegetable fertilizer for my container veggie plants just like coffee grounds?

Lisa | The Practical Planter

Monday 20th of April 2020

Hi, Willie!

Unfortunately, I don't see much information on the nutritional value of the leftover almond pulp, so I can't advise on using as a fertilizer like coffee grounds. If you are willing to possibly sacrifice a plant (also not really advised), you could try it out. You could also try using the leftover pulp for baking!