What is the Difference Between Potting Soil and Potting Mix

Potting Soil, Potting Mix, Topsoil…SO Which is Which?

Do you ever hear the words “potting soil” and “potting mix” used interchangeably? Do you wondr if they are the same thing or different products altogether? I know I was confused one time about these common products. You’re not alone – it used to trip me up, too. Especially when you go out shopping in the outdoors section of any Walmart or fill in the blank with venue name, and you see bags and bags of soil…or is it all really that?

Let’s start with potting mix….first of all, it is not really “soil”. It is a mixture of various ingredients that include vermiculite, peat moss, perlite, fine bark chips and sphagum moss. Hardly anything that constitutes “dirt”. Perlite is the little tiny white chips you see present in most mixtures, it always looked like bits of Styrofoam to me, but it’s actually a kind of mineral left from volcanic rock. Potting mix has a dry and almost lightweight feel to it when you pour it into something and stir it around with your fingers.

The white specks -the presence of perlite in a typical potting mix.

Potting mix is used primarily in container gardening and support media for houseplants….which due to a smaller volume enclosure, it makes perfect sense to not have a substrate that is compacted and sense to provide oxygen and freer movement for the roots. As you go about your watering chores, you may find that drainage is much better carried out. Compact soil may stifle the root structure and even if water can readily drain out, you still run the risk of having a plant with a soggy rout system, So if you’re trying to get into container gardening, the secret is to think light. Potting mix is your go-to here. Plants with “wet feet” do not thrive.

You may have heard the term “soilless mix” and yes, that’s exactly what potting mix really is. It is sterilized – free of pathogens and invasive materials like weed seeds, so for your indoor gardening endeavors, it’s pretty safe. Perlite and vermiculite, another mineral present, is a natural occurring trace product that helps in aeration of plant life. Perlite and vermiculite both have a neutral Ph and are sterile. Vermiculite helps in preventing the growth of fungi that can lead to “dampening off” as a result of too much moisture. It is not only a good top dressing for seed starting, but as it can absorb 3x its weight in moisture it can be used primarily as the only substrate too for seedlings. 

Now on with potting soil. If you’re like me and you’ve got elevated beds to fill up, this is what you should be using. Potting soil is actually soil – it’s a combination of different earth elements that include compost, aged manure and possibly some fertilizers…One thing to keep in mind is that it is not sterile like potting mix. It may harbor traces of fungi or soil-borne pathogens, but most likely it also may have beneficial bacteria present to counter that. It’s very dense and compacted – Which means, of course, it’s a weighty product.

potting soil vs garden soil
These are both examples of garden soil but you can see one is richer and denser than the other.

I can almost feel myself getting into my unloading and loading mode. WE’d come back from the store with 30 bags of soil and one thing we did to make it easier was to use the wheel barrow to transport about four bags at a time. SO yeah – if you focus on container gardening you’ll be dealing with much lighter stuff!

Some soils are richer than others, we got some that had mushroom compost and it was a wonderful booster.

Pin for Later?

difference in potting mix and soil

Topsoil vs “Garden Soil”

And topsoil, yeah topsoil is pretty close to potting soil.These words ARE used interchangeably, unlike “soil” and “mix”.Most soil you see present outside home improvement suppliers outside in the garden section, are labeled as “topsoil” The makeup may vary from brand to brand.

Because topsoil is used outdoors primarily, it hasn’t needed to be sterilized, as any bacteria can be countered. You are always welcome to add your own supplementing products to boost its productivity, or change the Ph. Of course, performing a soil test is advised before you make any drastic changes. 

Well I hope this article has enlightened you further and helped you understand the differenc es in these major substrates.Much luck to yo in your endeavors.


Leave a Comment

Your email address will not be published. Required fields are marked *

Scroll to Top