Hundreds of previous discussions on this question and I have linked many of them for you to browse through below.

But also check out the Container Gardening forum here for even more recommendations and even some recipes on how to make your own.

Since you asked about "potting", note that all the most highly recommended mixes for containers are soil-less mixes - no soil. Conversely, the worst container mixes are those that contain soil or dirt in them. They tend to compact, drain poorly, cause damp-off, and suffocate roots.

Hope this helps.

Dave

Here is a link that might be useful: Best potting mix discussions

Whenever you consider making or selecting a container soil, your priority should be that it maintains its structural stability and adequate aeration for the intended life of the planting. Particle size should be large enough that the soil retains little perched water (the water that occupies the layer of saturated soil at the bottom of the container when using compost-based or peat-based 'from the bag' soils). A mix of pine bark fines and perlite with a very small presence of peat or compost (5:1:1) makes the best container soils I have found.

Al

The worst "potting soil" I have used contained some regular soil and that drained very poorly and was the only time I ever had a problem with damping off. Most of the commerccially available "potting soils" are soilless, no real soil in them, for that reason. I have used, although some here will say that it will not work, compost as potting soil for many years now with very good results.

A 'soil' is anything that has a plant growing in it. It doesn't matter if it has a mineral component or not. If it supports plant life, it is a soil. What you described was a container/potting soil that had a notable volume of mineral/garden/topsoil .... in it. Most container media have no mineral component other than perlite, perhaps vermiculite, and dolomite.

When you start with an ingredient with fine particulates (compost) as the basis for your soil, it's very difficult to amend it so it drains well & retains ample aeration for an entire growth cycle. To get a picture of what I'm saying, imagine a bucket of pudding. How much perlite or gravel do you need to add to a bucket of pudding to get it to drain well? You cannot. After you reach 50% gravel or perlite, you've really added pudding to the other ingredients because pudding is represented at less than 50%, and it STILL drains poorly. Compost as the basis for a container soil follows in the same vein.

I'm not saying that you can't MAKE it work, only that you set yourself for an uphill battle from the very outset. Why not choose ingredients for your soils that have larger, more stable particles, and that will ensure a superlative combination of drainage and aeration for the life of the planting, instead of rigidly adhering to an ideology and fighting either soggy soils, or salt accumulation because you cannot water properly?

Al

A 'soil' is anything that has a plant growing in it.

That is a very loose definition of "soil" Al and not commonly accepted, especially when discussing container mixes because it only causes confusion. Thus the term "soil-less" and the synonyms for soil - earth, rock and mineral particles, dirt, ground, and land. I'm glad you went on to clarify: Most container media have no mineral component other than perlite, perhaps vermiculite, and dolomite.

Unfortunately there are many so-called "potting soil" mixes on the market that do indeed, contain plain old dirt and they should be avoided in container growing despite all the manufacturers claims to the contrary. A great example of this, among other brands, that has caused problems for many is Miracle Grow Garden Soil. Despite the instructions on the bag that it is not for use in containers the print is so small that many buy it in error and lose their container plants as a result.

But the definition "A place or condition favorable to growth; a breeding ground." comes in 5th or 6th place on the ranked definitions of the word SOIL. ;)

Dave

I use the word 'soil' and the term 'container soil' interchangeably and repeatedly, and it causes no confusion; people seem to understand perfectly well what I'm trying to convey. If I want to make a distinction between mineral soils in container soils (would that be a soil in a soil?) I usually advise that "As a general rule, a significant presence of mineral/garden/topsoil should be avoided in container media (soils)." The reason, of course, is the fine particulate size - the same reason I generally suggest limiting the presence of compost/peat combined to under 15% in pine bark-based container soils.

Miracle-Gro Garden 'Soil' is still a soil, just as Miracle-Gro Potting 'Soil' is a soil; it's just that the former is not suitable for use as a container soil.

I don't agree that the term container 'soil' is not accepted as a proper alternate to container media or medium, or that it carries with it the connotation that by the use of the word 'soil' it somehow suggests that the container soil also contains mineral soil. I've used the term container soil literally many thousands of times, and not once have I been called on it or asked to clarify. One term I don't use though, is 'dirt', unless I'm describing what's left under my fingernails after a day of working in the soil. ;o)

Al

I just took a closer look at the bag of potting soil that I have been using to fill containers. It is a mixture of diffent composts and composted peat w/ some lime added to balance the ph and a wetting agent. I do sift it to take out pieces of sticks and small stones that are sometimes left in the mix and then I add some peat and sometimes depending on what I'm planting some vermiculite or perlite. I've never paid alot of attention to the exact ingredients of potting soil, I basically just judge the texture and add what seems to be needed. I've been doing this for a long time and have not had any problems.

You have to judge plant by plant on what to plant them in. Some of my plants need more peat others more perlite. If I'm planning on hanging a container I try to make the soil as light as possible but still what the plant needs. Some plants grow in rock, some in water and others even in air. You need to have a little knowledge about the plant that you want to grow.

Good gardening, Mary

I DO pay very close attention to what is in my soils. I haven't used a commercially prepared soil for many, many years, choosing instead to make all my own soils. I used to grow in a peat/compost/perlite soil, but when I switched to pine bark-based soils, the difference in plant performance was very apparent - and stark. I never looked back.
For veggies & all the floral display containers, I start with a basic mix of

5 parts partially composted pine bark fines
1 part peat
1-2 parts perlite
dolomitic (garden) lime
micronutrient granules

For long term plantings and houseplants, I start with a basic mix of

1 part uncomposted pine (or fir) bark
1 part Turface
1 part crushed granite (grower size)
gypsum
micronutrient granules

The first soil retains it's structure and aeration 4-5 times longer than peat or compost-based soils. The second soil, with its 2/3 mineral component and the pine's longevity, will retain structure and aeration for far longer than it is prudent to go between repots - it will last several years, but by then the plant will be root-bound & need a soil change.

Soil structure and aeration are key when it comes to container culture. If you don't build adequate aeration and structural longevity into your soils when you make them, or those qualities are inherent in a purchased soil, you will be continually fighting the soil for control of the plant's vitality.

Al

If you want a good commercial potting mix..although somewhat expensive, Miracle grow..'moisture control" is very good for hot areas that need a lot of watering. You can use "soil moist" a product that has water granules that hold water in regular potting soil but the above product has it all in there for you. My container plants have done really well with it.

While it is important to know your plants and offer them conditions that they prefer, I believe it is far more important to understand how different the conditions are when growing any plants in containers as opposed to growing them in the ground. Because of the unique requirements associated with containers, the potting mix/media/soil is of high importance - Al's first post on this thread outlines the whys of this and his last (incuding his potting soil recipes) explains the hows. If you follow his excellent advice you will have consistant success growing any kind of plants in containers.

Unless you can find packaged mixes that offer very similar ingredients in proper proportions, I'd recommend you make your own. It's easy to do and can save a lot of money, both with the mix ingredients/components compared to the prepackaged stuff and with the success and life of your plantings.

I have been told several times that Sta-Green Moisture Max potting mix is the best you can buy. (It's sold exclusively at Lowes) It is a lightweight mix made up of Canadian sphagnum peat moss, composted bark fines, and horticultural perlite. There is an aqua-guard water control formula that protects against over and under watering and has fertilizer that's supposed to last up to 9 months.

This is my first year gardening and I'm doing a container vegetable garden because I have a small patio off my apartment. I bought the Sta Green along with a bag of steer manure/compost mixture and started with strawberry hanging baskets today. I'm not sure I should have added the manure/ compost mixture but I guess I will have to wait and see how it turns out!

I used mostly my own compost plus crumbled aged horse manure and a small amount of topsoil in my pots. Works FINE. Outside pots in the summer need watering quite often, so drainage is never a problem for me. I grow flowers and vegies in pots. Of course your mileage may vary.

Marcia