Whats the difference between 'Potting mix' and 'Potting soil'?

kris2001(6a - s.e.PA)April 22, 2008

Whats the difference between "Potting mix" and "Potting soil"?

When to use-which one??

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Potting soil is dirt, potting mix is a soil-less growing media suitable for containers.

Potting soil is for filling in low spots in the ground, a raised bed etc.

Potting mix is for containers.

A good potting mix is made up of particles much larger in size than soil particles. This is vital in a container because while the earth has a constant stream of water and air moving through it, a container does not. It needs to be of a larger particle size and capable of holding more air as well as capable of being watered more often (which brings fresh air in) without drowning the plants.

    Bookmark   April 22, 2008 at 2:09AM
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I'd like to add that, for the most part, out in the real worl---i.e. at the nurseries and garden centers---that distinction is not universally understood. distinction is not universally understood out in the real world.

When I go to my nursery, they use the terms interchangeably.

But for the purposes of THIS board, JaG's explanation is right on.

And if you haven't already done so, check out one of Al's many "container soils" posts and you'll understand REALLY well. :-)

    Bookmark   April 22, 2008 at 11:45AM
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While it is common to use the terms interchangeably (I catch myself doing it at times), I don't recall ever opening a bag labeled potting soil and finding anything other than dirt in it. Might be dirt with some sticks, rocks or even small weeds growing but still mostly dirt.

I tend to be a stickler about the term because so many do not understand there is a huge difference between what is in the bag labeled 'soil' and the mixes. Over the years both in real life and on forums I have listened to more folks than I can count talk about how poor their container plants are doing and when they identify what they are growing in, it's usually some cheap bag of potting -soil- they picked up not knowing any better.

So, I try to never use the word 'soil' when referring to what goes into a container so I am not a source of confusion for others.

    Bookmark   April 22, 2008 at 1:19PM
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JaG, agreed. And now that I have been here I know the difference. I don't think I'll ever use a straight bag of commercially available potting soils again. LOL

BUT... if a new gardener goes to a nursery and says, "I need some potting mix for my containers" they're likely to hand the person a bag of potting soil. My nursery has half a dozen products labeled "potting soil" and all purport to be great for containers. We know differently.

Likewise, if someone says, "I want to make my own potting mix," many many nursery staff people will not know what that means. The components of a good "potting mix" go by many different names, soil amendments, mulch, etc.

    Bookmark   April 22, 2008 at 1:30PM
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recluse(6b/7 NE TN)

Why do they call it "potting" soil? It's extremely confusing to a newbie (I was one of them). It's finally gotten thru to me that soil should never be used in a "pot", so I can't figure out why they market it that way.

My first inclination is to think they are just trying make a fast buck (purposefully misleading), but since I know the only way to make money is to have repeat customers this explanation doesn't ring true.

Do these people really believe that their customers can have success growing in containers using soil?

    Bookmark   April 23, 2008 at 8:04AM
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Sadly, many people do think they are having good success growing in soil in containers. My best friend's wife uses 'potting soil'. She loves the results. She also waters every day no matter what. The top of the soil could be glistening wet and she would still water.

I usually give her some of my extra flowering plants each year and I see how hers grow compared to the ones I grow and the difference is stark. Marigolds that are supposed to form 12" mini bushes stay in the 4-6 inch range, petunias that should grow vigorously enough to require a few trimmings throughout the season never get much beyond 6-8" long etc. She is very happy with her plants.

What can I say? Some people just do not understand the difference between a plant that survives and a plant that thrives. When she sees my plants she concludes that I have a green thumb and she could never hope to grow plants as well as I do because I have the 'magic touch'.

It isn't that, I simply don't use dirt in my containers ;-) That's my magic.

That gives me an idea. I think this year I will give her some plants already in a container with a potting mix. That will force her to see the difference in her own plant performance. Now, why didn't I think of that earlier???

    Bookmark   April 23, 2008 at 9:16AM
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As a former buyer of hardgood products for a retail nursery (and that includes all manner of soils, soil-less mixes, amendments, fertilizers, etc.), I have a bit of different perspective on this issue. In the business, the terms are generally used interchangeably to refer to a planting medium suitable for containers - i.e., pots. Even though there is no real 'soil' (garden "dirt", humus, loam, etc., for lack of better words) contained in potting soils, that is a term that most folks associate with what plants need to be anchored in to grow, so that term is still used. It's not done to deceive, it's just a term of familiarity to many, who may not understand the significance of or be confused by what is labeled a "soil-less" potting mix.

OTOH, planting mixes are soil blends that are intended to amend or supplement inground planting situations or for use in raised beds, conditions that are quite distinct from container culture.

And while I agree that there is a huge range in the components and quality of commercially packaged potting mixes, depending on where you are located, there are some excellent ones on the market, including any number of professional blends and some that are still labeled as "potting soil". I respect and value Al's opinion and experience enormously but I've been container gardening both personally and professionally for many years and I have never made up my own mix but used high quality purchased mixes only. And with excellent results. It's merely a matter of understanding the requirements of container growing and the plants you are including and making sure the mix you use provides sufficient aeration, porosity, drainage and moisture retention to address those requirements.

    Bookmark   April 26, 2008 at 9:34AM
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tapla (mid-MI z5b-6a)

Actually, I've been following this thread for awhile & was coming here to say something similar to what Pam said, but I hadn't yet distilled in my mind what I wanted to say. To me, soil is something for the plants to set their feet in, no matter what it's made of. I think that puts me on pretty solid ground technically, but I'm subject to correction by you guys if it's not accurate from a practical perspective. I don't use these things, but it seems to me the terms are used pretty interchangeably, so instead of sounding disagreeable, I'll ask a question: Aren't we eliminating a fair number of products that could be used with reasonable results in containers simply because they are labeled 'potting soil' instead of 'potting mix'? .... and then it follows: Aren't there media out there that are labeled 'potting mix' that are far inferior to others with the unfavored label 'potting soil'? If there's a point I'm making, it's probably that the most important consideration to me would not be what's on the outside of the bag (label), but what's on the inside. That said, I am fully prepared to allow that perhaps a higher % of media labeled 'potting mix' might be appropriate when compared to those labeled 'potting soil'. I really don't know.

Like I said, I don't buy these products. I walk by them & squeeze the bags out of curiosity to try to get a feel for what might be in them, or if there's a torn bag, I might pick some up to look it over. It really is just food for thought & more a question than an argument.

Pam offers: "I've been container gardening both personally and professionally for many years and I have never made up my own mix but used high quality purchased mixes only. And with excellent results. It's merely a matter of understanding the requirements of container growing and the plants you are including and making sure the mix you use provides sufficient aeration, porosity, drainage and moisture retention to address those requirements."

I'm proud to call Pam a dear friend & I agree with what she said. I KNOW she is an excellent container gardener; and of course you can grow vital, healthy plants in any mix that retains the physical characteristics she referred to. I'm not here to twist the arms of those who are satisfied and happy with what they use as media - especially growers like Pam. ;o) I always point out there is a balance between convenience and plant vitality in the mixes I grow in. I think that you can grow superior plants in the highly aerated mixes I use, but the trade-off is you have to be willing to water more often.

Some NEED the convenience of not having to water a little more frequently, and I understand that's a part of our individual growing experience - it is whatever we want to make it. I have tried all manner of bagged and commercially prepared media, even the Fafard blends, but I still prefer those I make myself, even though I'm very busy tending plants and an extended interval between irrigatings coupled with not having to make my own media would be a real blessing.

My main focus here on the forums is to try to help the folks who might be foundering a little - who might not be able to tell a good soil (oops) ;o) ..... a good medium from a bad one, those who really don't have access to a very good container medium and who would like to make their own, and those who are looking for a way to improve their soils, plant vitality, and growing experience through a better understanding of the 'whys and wherefores'. ;o)

Take care.


    Bookmark   April 26, 2008 at 12:25PM
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