"Potting Soil" and "Potting Mix" are essentially the same thing, a mix of various soilless ingredients such as peat moss, finely ground tree bark, coir, compost, perlite or vermiculite, and sometimes a fertilizer. For container growing it matters little which you use.

kimmq is kimmsr

bet, If, by garden soil you mean shovelfuls of soil from the earth vs bagged potting soil from the store, then yes, there is a big difference. The earth's soil is too dense to use in containers so bagged potting soil is better for plants in containers. But that opens up a whole new conversation about which potting soil to use. Personally, I avoid Miracle Grow. The one I prefer is a mix I buy from the local hydroponic store (aka marijuana grower's store). They usually stock Roots Organics, my personal favorite. Also Happy Frog or Ocean Forest from Fox Farms. These mixes use natural components instead of chemicals to enrich the mix. Hope this helps.

The OP is correct that potting soil should be avoided for container growing. I don't grow much besides a few herbs in containers and then I just use some of my Promix BX with a little compost mixed in.

There is a 'Container Gardening' forum here on Garden Web where knowledgeable growers discuss different mixes that they use including something called gritty mix, and 5-1-1 mix. Below is a link to that forum.

Container Gardening forum

Because there seems to be some confusion with terminology, let's clarify a bit and reiterate that 'potting soil' and 'potting mix' are essentially the same product - a soil-less mix intended for growing plants in containers ("potting" = potted or containerized plants). Because of the unique requirements of growing plants in containers, the planting medium must also meet specific requirements and this is why garden soil, compost or bagged products labeled as "garden" mix or "planting" mix are not appropriate media. The referral to the Container Gardening forum is an excellent suggestion, especially this thread, which explains the requirements and the differences of container culture in detail.

But not all potting mixes are created equal. Some - like the ever popular Miracle Gro - are quite inferior for this purpose. They are comprised of too much peat, they are too water retentive and with too small a particle size, leading to compaction and lack of proper aeration and poor drainage. You want to look for a durable and highly textural mix with a minimum of peat or coir and a good percentage of bark fines and drainage enhancers like perlite, pumice, granite grit or turface. The 5-1-1 or gritty mix referred to above (and discussed in depth in my link) are much better, custom choices but the Fox Farms products mentioned previously are pretty decent commercial choices.

Far more important what's IN it than how they label it on the bag.

As has been said, potting mix and potting soil are one and the same. That doesn't mean that all potting mixes/potting soils are the same (obviously) it just means that they are all referred to as mix, or soil or potting mix or potting soil. Some stirrers will call it dirt, just to annoy anyone who is pedantic.

(We had one such person who got upset if an apprentice said, 'dirt'.

There are times, I must admit, when I have thrown good sense out the door and decided that there is no reason why I can't put garden soil in a pot to grow my ____________ (fill in blank). So in goes the soil - real proper, live garden soil - and it's nice, this soil. But of course it is a disaster. It totally loses its structure when it is treated in this appalling fashion and suddenly there are no air pockets and soon it sets like concrete.

Some time will pass and I will try it again, convinced that I can make it work.

When I think about it, I am not even certain why it doesn't work. Maybe it's a perched water table problem but I always have the pot in direct contact with the ground so that drainage can occur via capillary action.

I think I need to do another experiment. Obviously my drainage in that situation is not good enough???????????????

Any thoughts, anyone?

Did you read the thread I linked to in the Container Gardening forum? That will explain in detail why garden soil (and also a good number of packaged potting soil mixes) does not work well in containers. Growing plants in the ground and growing plants in containers are two completely different growing situations with two sets of very different growing requirements, with the 'soil' medium being the most significant distinction.

btw, having a containerized plant in direct contact with the ground does not eliminate the PWT - that will exist regardless and the ground contact can actually reduce the ability of the pot to drain well. Best to have the container elevated to some degree.....like with pot feet or rocks.