Here is the hard truth about potting soil. As long as it is made of quality ingredients such as peat, some non organic matter like perlite or vermiculite it is good potting soil.

Everyone and their grandmother has their personal favorite and some folks even go so far as to have several favorites for different things. It doesn't matter. When you look at bag after bag of good potting soil you will notice that the basic components are almost always from the same very short list of ingredients. Differences are simply the ratios of each component, whether or not fertilizer is added, whether or not wetting agents have been added etc. They are all good as long as you stay away from the cheap stuff which is often nothing more than yard dirt in a bag.

About the only differences that matter in commercial potting soil (of the good types) is ph and drainage ability. For acid loving plants that require a low ph you want a potting mix that is ph adjusted. This would be for azaleas, potted blueberries and other low ph lovers. If you are growing cacti or other dry soil prefering plants then you will want a cacti mix which usually has less peat and more non organic stuff and perhaps a good deal of sand/grit in it.

So, consider potting soils to be of 3 types: regular, low ph, and sandy/dry. As far as brands, just stay away from the cheap stuff and stick with names like Schultz, Miracle Grow, and others commonly found in stores. Alternately you can have many nurseries sell you their own custom blends which should nearly always be good.

As far as compost goes it is always unnecessary it potting soil. Always. It can be desirable though as compost hangs onto moisture reasonably well while being fast draining and it has a wealth of micronutrients in it which can compensate for anything lacking in the fertilizer you use. Compost is good stuff, but it isn't necessary in a potting soil. Having said that I almost always incorporate compost into everything, yard soil and container soils. The 1/3 compost, 1/3 peat, 1/3 vermiculite will make a fine growing medium, but it would be a bit 'heavier' than what I personally would like in containers (pots). Like I said, everyone has their idea of what is 'best' and you just saw some of my bias show through. Ignore it ;-) Any old bag of potting soil is good quality as long as it isn't the cheap yard dirt in a bag stuff. That is easy to spot because the bags weigh more than comparable sized bags of other potting soils wet or dry.

Hi, DesertHills. About the only things I agree with in the preceeding post (username's) is that the soil might be a little slow if you're using it in a container (maybe not though, given where you live) & you can leave the compost out. You mentioned SqFtGardening. Are you growing in a raised bed? If so, the soil should be fine.

Al

Thanks for sharing your thoughts! Maybe I need not worry so much about soil but I do want to start right :)

Sorry if I sound confusing, I confuse myself too. :) I haven't started to grow veggies, and would like to. The idea of intensive or sqfoot gardening appealed to me. I'm thinking of using a maybe a box of sort outside, wood or plastic, so that I can move them around depending on the seasonal sun exposure, e.g. put them northeast during summer, then southeast during winter. Also, I might put them up on a platform so when Mom visits she can tend the veggies without bending so much. So I guess this isn't a raise bed, please correct me if wrong. This is how I stumbled in to the container forum.

In this case, would 1/3 compost mix be too heavy? Maybe I need to follow a "modified version" of the sqfoot idea?

~ Esm
*trying not to step on people's toes*

Oh golly - you didn't step on anyone's toes! - and I didn't even realize it was you, Esme. I remember our recent conversations about lasagna beds. ;o)

Is it a raised bed? Almost. If there is continuity (contact) between your soil & the soil of the earth, it will act like a raised bed - almost. The actual soil can act as a wick & drain almost all the saturation layer from your container if you set up your container that way. a wick or wicks would insure the contact between the soils.

Try a container with your mix if you wish. Plant something in it & see if it needs watering daily after the plant is established. If it does, the soil isn't too slow in the drainage dept, but aeration could become an issue later as the compost & peat start breaking down.

If you have compost & want to use it, & your containers are on the ground, & I was in your place (and in your neighborhood), here is what I would try.

3 parts pine bark fines
1 part compost (well composted manure would be great)
1 part sphagnum peat
1/2 - 1 part perlite
slow release fertilizer
small amount of 10-10-10 or similar
something for micro-nutrients
You could even add some coarse sand (BB size)

You could see how this works & make any changes you need in the next batch. I'm guessing your water is probably high in pH, so I wouldn't add lime to the soil (if it is).

More questions?

Al

Question for Al (tapla): Where do you find BB-size coarse sand? I've never seen any of that size grains but would like to find some.

Screen it from a natural source , roofing company, masonry supply business, pool filter sand (the big stuff). I use crushed granite. It is very irregular but all the same size because it's screened (great for drainage AND aeration) & is available in big bags (80 lbs?) for about 5 bucks from animal feed stores. That's too cheap for me to go through the work of screening it myself. I use two sizes & they are called grower grit for the large, BB size & starter grit, which is about 2/3 the size of grower grit. You really don't need any sand in a mix that you don't intend the plant to stay in for more than a year. Perlite is a better choice unless you're growing woody material, which seems to fare better with a lower organic % in the soil. Using perlite as the primary inorganic component of such soils makes them too fast to be practical, so the Turface & granite are used instead. This is probably going farther in search of a perfect soil than most of you guys are willing to go, but you can make some very long lasting & healthy soils from only bark, granite, & Turface in equal proportions. I use it on all my woody stuff, but don't bother using it on the flowery containers, & wouldn't use it on veggies if I grew them either. I use the mix I posted in the container soils thread for that stuff.

Al

---Thanks for sharing your thoughts! Maybe I need not worry so much about soil but I do want to start right :)---

Well, soil is important, but when growing in containers the soil isn't very important outside of a few basic criteria. It has to drain well rather than swamp plants, but most any soil will dry well in a container. The soil needs to be heavy enough to support the fully grown plant and most commercial mixes, while light, support plants fine. Lastly the mix needs to be able to retain nutrients long enough for plants to access them.

Anytime anyone tells you that a particular mix is the 'best' just tell them that hydroponics involves growing plants in aerated water, not soil and those plants often outgrow and outproduce soil grown plants.

Many will tell you that you need a rich soil meaning nutrient rich. That isn't true at all when talking about containers. There is no such thing as a nutrient rich potting soil for containers. No matter what you do you will have to supplement the pots with fertilizer regularly.

Make sure your soil mix is OK for the ph requirements of the plants and beyond that most any soil will work in containers other than clay based soils which dry and pull away from the sides of the pot making watering a pain.

-- Sorry if I sound confusing, I confuse myself too. :)--

It isn't your fault. Gardening is one of those activities where there are a lot of old wive's tales that will not die. You will hear about how potting soils need to be fast draining and need to retain water well. Those 2 criteria are mutally exclusive so the advice is nonsense from the start ;-) Next time someone tells you you need fast draining, moisture retaining potting soil just ask them how you can have fast draining and mositure retaining at the same time. It is kind of fun to watch the smoke come out of people's heads on that one.

--- I haven't started to grow veggies, and would like to. The idea of intensive or sqfoot gardening appealed to me. I'm thinking of using a maybe a box of sort outside, wood or plastic, so that I can move them around depending on the seasonal sun exposure, e.g. put them northeast during summer, then southeast during winter. Also, I might put them up on a platform so when Mom visits she can tend the veggies without bending so much. So I guess this isn't a raise bed, please correct me if wrong.--

What you are describing is not square foot gardening, but container gardening. They are completely different, but share something in common. They are intensive gardening methods. Now, with respect to Mel who popularized the intensive gardening method for our generation, he didn't invent it, it has been around a long time and it was modern, machine harvested agriculture that caused folks to lose site of it. Read the back of a seed packet and look at the spacing guidelines and you will see another old wive's tail. It will say space plants 6" apart in the row and space rows 24" apart. Why? Do the plants grow 6" wide and 24" long? Nope, the silly spacing guidelines are all based upon the assumption that mechanical harvesting will be used and so rows have to have enough space between them for tractor tires. All intensive gardening means is packing plants in as closely as they can be successfully grown and providing enough water and nutrients to keep things going.

-- This is how I stumbled in to the container forum.--

Well, glad you made it ;-)

-- In this case, would 1/3 compost mix be too heavy? Maybe I need to follow a "modified version" of the sqfoot idea? --

Honestly I don't know anyone in real life who uses the Sq. Ft. method precisely. It is just an intensive gardening method that has been around for over a thousand years and was made popular by Mel when he wrote a book that effectively dispelled a few gardening wive's tales. Would 1/3 compost be too heavy? Well that depends on you. You have to consider the wet weight of the pot when you try and move it. Compost is fairly heavy as far as potting mixes go, particularly when wet, but that can be a good thing or bad thing depending. It is certainly not too heavy for any plant and in fact there are many people who skip potting mixes and just grow directly in compost.

In containers don't worry about the soil other than it not be clay based yard soil. In ground gardening the soil becomes much more important. Most any potting mix is going to be just as good as the next one. To grow veggies you will need to water frequently, and fertilize regularly, regardless of the soil. The soil mix doesn't do anything other than hold onto the water and fertilzer while supporting the plants.

Always remember, you don't need any soil to grow plants, they can almost all be grown as well, if not better, in aerated water, under artificial lights. I am not saying you want to start growing hydroponically, I am just trying to set the relative importance of soil mixes into perspective. As long as it is a mix using standard ingredients it really doesn't make any differnence, the soil isn't doing anything other than providing something for the roots to grow in. You have to add the right amount of food and water regularly and position them to get the correct amount of sun. These are all far more important than the type of potting soil except for the low ph requiring plants which need a low ph mix.

OK, I realized that I am probably confusing a lot of people with my previous posts. I will attempt to clarify.

Potting soils and recommended mixes are generally geared for ***indoor*** pots. This is why I say that potting soils are largely interchangeable ***for outdoor pots***.

Fast draining is good inside where they don't dry out quickly, but outside these mixes all dry out too quickly leading to having to water every day (or more) in the hottest parts of the year.

Just as the spacing on the back of a seed packet usually makes no sense for home growers, but makes good sense for commercial growers using mechanical harvesting we see the same thing with potting soil recommendations. They make good sense for indoor pots, but not much sense for outdoor pots.

No matter what commerical mix one buys it will not hold enough nutrients or water when placed outside and the end result is that one has to water and fertilize frequently.

Loam based soils are better than peat or bark based soils in retaining water and nutrients, but one can simply take any old potting soil and add compost to achieve the same effect.

This could end up being an extremely lengthy thread. I'll make some quick notes here on what I agree with in your post & what I disagree with. For the sake of brevity, I'll offer comments that are short as possible. Most of what you set forth is covered in a post about water movement that is currently on the forum . If you haven't looked at it, it will give you an overview of my thinking on container soils. I would be happy to discuss anything I set down here that any disagree with.

I agree that soil needs to support the plant & hold water & nutrients and drain quickly, & the part about hydroponics (in my post, too). Agree there is no "best" soil, but there are poor, OK, better, & much better. Agree there are no natural nutrient mixes for containers (that will consistently work well).

I often advise the "nonsense" that container soils need to drain well & retain water. The two are not mutually exclusive. In our search for a productive soil, we need consider the particulates. Large particles that are fairly uniform in size, absorbent & irregularly shaped provide both excellent drainage and water holding ability. Micro-pores in inter-particulate spaces as well as those in the particles proper hold water well, while the macro-pores created by the larger particles drain freely, providing excellent aeration/gas exchange at the roots.

I'm back. I had to go find a mirror to check for smoke. Fortunately, none there. ;o)

Ph adjusted soils? As soon as you water, they become pH unadjusted. Generally, chasing pH numbers in container soils is an exercise in futility. Plants normally grow over a wide pH range & the pH of your water is far more important than the pH of your container soils proper.

Most any potting mix is going to be as good as the next one? In a recent presentation on container soils, I used a (right from the bag) "premium" soil to illustrate just how nearly impossible it would be to grow in that medium w/o substantial amending. Not just any old soil will do. It must be able to insure aeration for the life of the planting, or the plant will be unable to come close to growing at its potential genetic vigor.

You said: "No matter what commercial mix one buys it will not hold enough nutrients or water when placed outside and the end result is that one has to water and fertilize frequently." More often than not, I find the opposite to be true, & I can find no room in my assortment of soil ingredients for loam in a container soil.

Al

This has been an interesting discussion, thanks for being supportive! I'm glad coolheaded members hang around this forum. I think I'm braver now to jump right in with container planting .

I have to agree overall with username. I think that sometimes we take the "fun" out of gardening if we get too academic about it and then never get started because we are so worried about what to plant in - even moreso a bit overblown if it's just for annuals to grow during a season.

Everyone has different microclimates in their growing space - god knows I'm up some 150ft in the sky in a brick and concrete building with a 40ft long NE-facing balcony that often gets westerly winds blowing across and Nor'easters in fall (which become blizzards in winter). And thus after watching how my plants react to this depending on where they are situated, I have gradually observed enough to help me decide how to pot them. In general, I have found that the name brand container mixes (and I currently use Promix), are pretty good at sustaining a plant. I may take that and supplement with some peat for acid lovers, but in general, the drainage is pretty decent provided I don't overpot the plant - particularly one that isn't a fast grower in the first place.

I have actually top-dressed the past couple years with a little compost and shredded oak leaves on my blueberries and they have responded positively to it - each year sending up new fruiting canes from the base. Concurrently, I'll prune out the older canes when I see them in decline - not unlike what people who maintain blueberries in the ground do. I give 'em a little Hollytone and they're all set.

I know that there have been some rather rancorous threads on the Citrus Forum of late regarding the use of CHCs as a potting medium - sometimes supplemented with some soil. This supposedly eliminates "overwatering". But as noted, it's all up to the person and how much work they want to do to maintain a plant in whatever media they come upon that is successful for them - whether nutrient solutions, coir, soiless mix, CHC, or even plain old "top soil". And oddly enough, my mother insists on potting her tomatoes using bagged top soil and fertilized with regular Miracle Gro, and they grow just fine in a south-facing spot in her yard. They're obviously annuals and not intended to be grown for years in that medium, but they have been very productive when she has potted them like this - every year for many years - much to my surprise.

Considering that I have plants that are quite potbound (thus necessitating root and top pruning), and being that even with the large balcony, I still have to grow in a limited space, I resigned myself a long time ago, that I cannot nor would I want to try to compete with the ground gardener for plant size. I want the plant to be balanced and healthy, blooming when it should and able to be pruned to maintain healthy new growth. There's nothing better than to step out on the balcony in spring and get a magnificent waft of fragrance in the evenings from my lilacs when in bloom, or to be able pluck and munch fresh blueberries that sit just outside my bedroom door, or watch my little lady hummingbird nectaring on my bee balm, or watch my clematis try to attach to anything nearby while I futily try to keep it trained to its support.

As the saying goes - "YMMV" ("Your Mileage May Vary").

You'll find my posts all over these forums saying that many grow a variety of plants with good success in commercially prepared potting soils, so that's not an issue. Are there better alternatives to those commercially prepared soils? It's foolish to propose there aren't. Are they adequate? Probably more are than aren't, but would you want to go to the moon in a rocket ship that's probably adequate? (That one, compliments of my dad. I only changed it a little to fit here.) ;o) I do realize that rocket science has nothing to do with container soils - unless you want to treat them that way, because they certainly can be.

I'm not exaggerating when I say I get at least 6 plant related messages in my mail every day - sometimes as many as a dozen. Many of the participants here (from this forum and others) ask frequent questions off forum, and often I'll get questions directed to me on forum. A good percentage of them are soil related & the highest percentage of the soil related questions are about problems are caused by poor drainage and/or aeration. In many cases, there are up to a dozen e-mails exchanged so I can find out all the facts before making a suggestion based on everything from plant material, to experience, to how seriously the gardener wants to succeed, to financial considerations, and more. More often than not, correspondence continues long after the problems are subdued or reduced to a manageable level.

In Jenny's post, she said that the mix she grows in is "pretty good at sustaining a plant". When I get questions, if the questions are coming from some one who would actually be taking a step up by beginning to grow in a pretty good soil (because they are currently trying to grow in a pretty bad soil), and they are happy with the upgrade, then I'm happy, too. However, if they want to take the pains to learn to get closer to being able to build the best soils possible from what they have available, instead of relying on a commercial mix, they'll always find me ready to help. I often observe evidence of bruised egos when I say there's a better soil than Sally Sue is growing in, or a better way to do something, and it just happens to be the soil Linda Lou uses or the way she is doing something. Linda Lou often disagrees, but in most cases, is also often short on reasons for disagreeing. I can point that out, but it will never change - it's human nature.

I don't criticize anyone's choice of soils, but I frequently point out that many growing problems originate in the soil, and there are alternatives to the problem. When I say I don't like sand or I don't like compost, I state why, so the reader can decide if what I say makes sense, and if someone wishes to disagree with me, they have the information to make a clear case. Username was pretty good about doing that (giving reasons) in his post and I was easily able to single out what parts I disagreed with.

I always give less consideration to posts that say things like - I disagree because: "I always do it this way", "I (or someone else) have/has been doing it this way for years and it works for me/them", etc. I also give greater consideration to posts that explain clearly the reasons for the disagreements.

At this point, I might also note that in almost every post I write, I try to share a little extra something over and above the question. To some, it might be annoying, or seem like I'm showing off, but I get great satisfaction in thinking that someone might be learning from something I might say, or that after reading something extra I might have said, another piece of the puzzle drops into place. I do try very hard to help keep the "fun" IN gardening by helping when I can. To my way of thinking, the "fun" is generally pretty scarce when success is elusive, so if some of the things I say get people to thinking, even improve their success, that's wonderful. If all anyone learns from my posts is that watching your plants and really thinking about what they are observing is an important key to successful container growing, I'd be pleased as punch with that. I can't even guess at how many times a new gardener has written me with panic all through the message. Want to know what fun is - for me? It's seeing the panic dissipate, the confidence return, and the excitement of being on the cusp of their first successful gardening experience return.

So - again, there's a little something no one asked for - about where I'm coming from as I participate in/on these forums. Those that know me or have corresponded with me will know that my motives are pure & I am genuinely interested in helping folks, others will have to make up their own minds.

It helps me to think I know what I'm talking about, otherwise, in good conscience, I wouldn't be able to post. Readers will have to make up their own minds about that as well. ;o)

Al

"The idea of intensive or sqfoot gardening appealed to me. I'm thinking of using a maybe a box of sort outside, wood or plastic, so that I can move them around..... Also, I might put them up on a platform so when Mom visits she can tend the veggies without bending so much. So I guess this isn't a raise bed, please correct me if wrong...."

DesertHills... you are NOT wrong and you ARE talking about square foot gardening. :) If you have the book, then you know that Mel does show boxes raised up for the handicapped (or elderly). The idea of square foot gardening is NOT in WHAT the box is... or WHERE it is... or even IF it IS a box or not. It is the dividing up the soil IN the box into "SQUARES" and spacing your plants closer together. So if you put your box on something that will support its weight and it has wheels on it then you can roll it around to your heart's content and your Mom can enjoy working in your garden. :)

"What you are describing is not square foot gardening, but container gardening. They are completely different...."

:) That statement didn't even make sense. Square Foot Gardening is about a plant spacing method...NOT what is holding the soil. It can be done in a box, in a raised bed, in a container, in the ground, in a bathtub... You are just NOT "square foot" gardening if don't space your plants in square foot blocks. ;)

"Honestly I don't know anyone in real life who uses the Sq. Ft. method precisely."

Hello, nice to meet you. :)

"As far as compost goes it is always unnecessary it potting soil. Always. It can be desirable though as compost hangs onto moisture reasonably well while being fast draining and it has a wealth of micronutrients in it which can compensate for anything lacking in the fertilizer you use. Compost is good stuff, but it isn't necessary in a potting soil. Having said that I almost always incorporate compost into everything, yard soil and container soils. "

haha :) I'm sorry but that was really funny and is the kind of contradictory statement that will totally confuse a beginner.

"In containers don't worry about the soil other than it not be clay based yard soil."

In other words, don't even bother buying a "soil-less" mix. So...if you have yard soil that is not clay based, then just use that in your containers too. After all... "yard soil" is Mother Nature's compost... it's just some of her piles worked better than others. ;)

In my personal experience, I don't like bagged soils that are very high in peat or vermiculite. They dry up and shrink away from the sides of the pot, are very hard to keep moistened, and pack down like bricks. That is just my own observation.

DesertHills, I am sure you are probably sorry you even asked by now! ;) Although I have been laughing all the way through this post!

"For those who have lasagna garden that prepare their bed in the fall for spring planting - Do you cover the top to prevent weeds? "

Okay, as to your other question, I have the book on that one too. It states that you can plant fall-built lasagna gardens right away, let them 'cook' first, or just leave them to break down naturally over winter for spring planting.

TO "COOK" YOUR LASAGNA GARDEN: ....Put about four times as much brown material as you do green material. Apply the material in 4-6 inch layers, adding a sprinkle of organic supplements (such as wood ashes, bonemeal, and lime or sulphur if you need to adjust the soil's pH). If you have a ready supply of compost by all means add layers of that also. Once the bed is 18 to 24 inches deep, cover it with black plastic and weigh down the edges with bricks. The plastic helps keep the materials moist and traps the sun's warmth for fast heating. You can leave the plastic on for about six weeks and most of the mulch will have broken down into a dark, crumbly material that's a joy to plant in.

So... you could cover yours with black plastic and leave it for the entire winter. Or you could cover it with mulch as you would any other bed (but most of the pile is made of mulch materials....so what would be the point?) There are a lot of folks over in the Soil Forum who chat about lasagne gardening all the time (if you haven't found them yet). They will probably have all kinds of tips for you. But if there is any other questions I can answer for you just let me know. :)

one added note: Lasagne Gardening has also been around for centuries and was commonly called "Sheet Composting". :)

Anyone truly interested in soil and its composition ought to check out the Soil, Compost, and Mulch Forum. There's always lots of interesting information, comments, and debates there from experts in the subject. And it's not limited to just ground gardening but soils in general.

Well Desert Hills,

I think by now you can see that those who have posted here all have different ideas on what to use for potting soils.

Let that be an encouragement to you that in all likelyhood whatever you choose will work 'well enough'. ;-)

I don't understand why there is so much resistance to Al's idea about soil. A soil that is just "well enough" when you can easily have something better makes no sense to me.

Excellent point, japaninvirginia. :) I would also like to add that the advice Al is offering to all who ask is not some cockeyed idea he just dreamed up. . . the information is in many books I have read. He just saves us all the money for the books and he can give us hands-on experience info because he uses the mixes he talks about.

"Well enough" is plain old dirt...with your plants responding accordingly.

I think I said this before on this forum or maybe it was another one, but I know Al casually and through these forums and e-mails. I have visited his garden and seen his containers and bonzai. A friend took me on a drive past his garden several years ago. he was outside working and I met him briefly then. His garden is perfect and one of the best I have seen and I have never seen such a variety of healthy plants and trees growing in containers. Then,I heard him speak to our group about soul and growing things in containers. We were sure he was a professor because of all he knew about plants and how easy he explained it so we could easily understand. I just want to add my 2 cents that I have seen that he doesn't just talk the talk.

Scheesch. I'm a little embarrassed & don't know what to say, except thank you Mike, DaisyLover (is that you, Shirl?), and Marti (I still have a plant here with your name on it.).

I think what Marti meant was I talked about "soil", but I have had many enjoyable (actually, way more than enjoyable) discussions with gardeners about the soul we all put into our gardens for safe keeping. Wouldn't that be a neat idea for a new thread?

Take good care.

Al

>> soul and growing things
Caught my attention too. I think it makes sense.

Is it simply screenings from pine bark mulch? Is it widely available?

I used to have a steady and reliable source, but now it often takes some searching to find a partially composted mix of small pine bark particles, which is what I prefer to use. The particles range from very fine up to 3/8 inch. I often find this product being sold as soil conditioner & it's usually made from southern yellow pine bark. I suspect it's a by-product of companies that treat outdoor lumber to increase its resistance to rot (the bark, of course, hasn't been treated). If you would like to see a picture of what it looks like, send me a note & I'll attach it to the reply.

Al

I found this soil conditioner at Home Depot, works great. And my plants are immediately showing improvements and new growth after using Al's formula.