Best & Worst Potting Soils

I would love advice on what are the best & worst brands of off-the-shelf premixed potting soil. I made the mistake of buying a bag of potting soil "Packaged for Wal-Mart." I think it is just sand and wood chips died black so it looks good. My plants however, aren't fooled...they don't seem to care for it.

I will post details etc. when lunch is not asking to be eaten, but I will tell you to only buy Miracle Grow or Scotts. (As far as nationally known brands) Even other soilless ones are bad. Again, explanation later.
K. James

Why not? I use Jiffy mix. Will I suffer eternal damnation for this?

Alas, I refuse to use MG or Scotts.

Do you have a reason for not using MG or scotts?

Ah, Zep, I've only used the Jiffy seedling mix; having too much vermiculite, I was not impressed. But I cannot speak for a regular mix, as it may be the same formulatioon as the MG & Scotts. (I must admit to not having used Scott's for a few years because of availability, but I recall it was the same as MG. ) I am curious what have you against them. They are pretty patronizing. (Of course, what specific use we are speaking for makes it all fall down differently! )

For "general use:"
My two-brand suggestion was simply a no-fail suggestion that now bears some explanation.

First: Usually, a person does not want to use a soil-based "potting mix" which is what the really cheap stuff is. An example is "Hyponex." It is downight nasty, leading to the slow downfall or severely decreased vigour of plants.
A "Soiless" mix is what they often call a potting "compost" in Engalnd, (so if you ever read it in a U.K. publication.)
The contents of standard (MG & Scott's) mix is as such: A majority of peat moss, finely ground woodchips/bark compost, and perlite for drainage. The Cornell mix, intended to make the drainage properties of the perlite, is 1/2 peat and 1/2 perlte. This has no nutrient value (Alright, very little) and needs a micro- and macro- nutrient fertilization, but it is of ideal texture.

Second: There are soiless mixes, too, that are not good. I experiemented with "StaGreen." If the attack on proper English in their name is looked past, it is a soiless mix that is too heavy on larger wood materials (hardwoods, I imagine) that deplete nitrogen as they break down. I found that seedlings grown in it (without fertilizer) suffered from nitrogen chlorosis. I have found the same in full-sized potted plants as well to a lesser degree.

Here is where I shatter all of the above!: Bagged potting soils are often, but not always consistent. The mixtures can vary bag to bag! To avoid this, you can make your own potting soil, or use soiless compost from your garden (sifted and sterilized). You can tailor it to meet you own needs. What I am trying now for seedlings (with good results thus far) is MG and coir, equal parts.

That's enough, K. James

I am about to try to make my own potting soil with these ingredients: Pine bark mulch, cow manure, perlite, and osmocote. I need to find a container that's big enough!! I took a class at a local nursery and she recommended these ingredients. Now if I could only remember the ratio..... :) The woman who was teaching the class doesn't recommend ANY of the brands of prepacked potting soils on the market. She said if she HAD to buy one, it would be "Brown Earth".

Willmetge, I don't use MG or Scotts b/c, as a fan of sustainable agriculture/permaculture, I'm not real thrilled with the fast-food, long-term impact of MG/Scotts' usual ingredients on soil. I do use, as I said, the unfertilized Jiffy seed starting mix once a year for seed starting warm-weather crops (and do not fertilize seedlings until they're in the ground a few weeks), but otherwise sterilize garden soil and compost for my pots and other seed starting. I plan to use garden soil exclusively next year. That's just how I prefer to do it from an old-fashioned point of view. I recognize most folks disagree.

One take on MG in Garden Terms: http://davesgarden.com/terms/go/2307/

I mix my own too cheap to buy someones name. I use my composter that doesn't compost, to mix soil you know the barrel on legs that you can rotate.

Ouch, chicory, it didn't work as a composter? That must have irked you if you're a penny pincher. :) Good it works as a mixer, anyway.

What your soil is made from is less important than how it retains its structure. I grow many plants in an all mineral soil (nothing organic in the soil whatsoever) and some in an all organic soil. Most soils I use are a combination of ingredients I keep on hand at all times.

The most frequent source of problems in containers can be found in the inverse relationship between aeration and drainage. "Primum non nocere" (to your soil) should be the container gardeners oath. "First, do no harm". If you build your soils with the idea that they MUST retain good amounts of air for the intended life of the planting, you will have topped the highest hurdle in container gardening.

Air is as important in soils as water, yet we seldom give aeration a thought. In container culture, we can easily manipulate the requirements of water, light, and nutrients, but little can be done about aeration once soil is made & plants are planted. That is why it is critical to insure that you use a soil whose structure guarantees it will hold ample amounts of air for the entire life of the planting.

Kristen - You've been given some excellent advice. The only criticism of her ingredient list is that I would lose the manure. It's only benefit is the micro-nutrients it supplies, but it gives them up at the price of breaking down too quickly, clogging valuable soil macro-pores, and the weed seeds it brings with it. Instead, I would include a fish/seaweed emulsion or a micro-nutrient frit or powder to supply the minors.

If you want an excellent mix, try:
5 parts pine bark fines
1-2 parts sphagnum peat (no reed or sedge peat, please)
1-2 parts perlite (coarse grade is best)
controlled release fertilizer
dolomitic lime
micro-nutrient source

Because the bark is rich in a lipid called suberin, it breaks down very slowly, which allows it to retain its structure and hold air. Peat, in these lesser quantities doesn't impede drainage much, and will wash from the container as it breaks down. The perlite, of course, is further drainage/aeration insurance. I, many/most of my friends, and many dozens of folks from a competing forum are growing in this mix. All have expressed thanks for sharing it. It is also versatile enough that it can be easily modified with a few other ingredients to be better suited to succulents, woody plants, cacti, others.

Some things I will never use in soils that are commonly recommended: Compost - sand - garden/topsoil. Compost brings nothing to soil except micro-nutrients, and it ruins (or at least diminishes) aeration and drainage. Use an alternate source of the minor elements. Sand/topsoil, while it may not harm drainage, does fill macro-pores and reduce aeration. If you wish to use a mineral component in soils, large particulates, around BB size are fine. I use two products extensively in soils, a baked clay granule called Turface, and grower grit, which is crushed granite with an irregular shape and sharp, angular edges. The granite promotes drainage and fine rootage, while the Turface holds water and nutrients very well while at the same time it also promotes drainage.

I expect some will say, "I've done it this way for 90 years" or "I always .... and it works for me." Even though these replies are not too scientific, I'm fine with it, and wish no one to change what is good enough for them. For those that want to consider the science behind what I offered, you can build some killer soils you won't find in a bag.

Al

Here's my 2 cents worth.
Most commercial mixes contain too much peat which causes it to dry out too quickly.

I mix my own as follows:
3 parts potting mix
1 part compost
1 part potting soil
1 part perlite

I also use the polymer crystals (soil moist) for my containers.

Paul



This message was edited Feb 3, 2006 4:37 PM

Asking gardeners about soil is like asking faithful about religions!

Very nice info here. Whenever possible, I like to be a penny-pinching independent and make my own. But I admit to taking the shortcuts often. Peat grows things, but it is quite ridiculous in the whole environment scheme of things. Aeration is a good thing I forgot to add. It has got to be the most forgotten necessity of plants!

I must admit to having a silly thing against using perlite personally- I don't like how it crunches, the dust when it is dry, or worse (this is all in my silly head, remember) the way it looks like what it is- perlite specks- when it makes it out into the garden.

Who else has an irrational vandetta against a medium?
K. James

I really don't like plants that come in soils that drain so quickly that almost every bit of water put in comes right back out and the plant is bone-dry by the afternoon. I know this provides great air to the roots, but my guess is that nurseries do this to keep water-happy employees from killing their plants.

The trick is to use soil parts whose shape and size provide macro-pores for air holding and micro-pores in the soil particles themselves that hold water. Where you run into problems is when you allow peat or bark soil particles to become drier than a 30% moisture content. When this occurs, the arrangement of iron ions on soil particle surfaces causes the soil particles to become hydrophobic (water repellent). This can usually be overcome by wetting the soil surface and returning in a few minutes to water thoroughly a second time, or not allowing the soil to dry too much. Of course, this last is difficult if the soil drains poorly or holds too much water, making an even better case for a soil that is well aerated and drains well.

Al

Tapla --- 1) What are "pine bark fines"? A bag of pine bark mulch labelled "Fine"? (as opposed to medium or large). 2) What is a "micronutrient frit or powder"? 3) How do you modify your recipe for cacti and succulents and woody plants? Thanks for your help.

In these parts we use a soil amendment which is finely milled pine bark called by the propietary name "Nature's Helper".

YardenMan - Cool name. I have a friend, SurePlantsAlot. For some reason, your name reminded me of hers.

Forgive me, I don't know how to post several pics in a single post, so I'll string them out. Below is a pic of some stuff I use for soils. From 12:00, clockwise: partially composted pine bark fines - then, fir bark - at 6 is coarse perlite - then, uncomposted pine bark. The uncomposted bark works fine, but requires less perlite in the mix, and a little more N in the fertilizer.

Al

I use a micro-nutrient powder by Scott's, called Micromax. It is available in 50 lb bags & is expensive - about $75 before shipping. I have a source for it in small quantities, if you're interested. You can use other supplements that contain the minors with good results, too.

Micromax: http://www.scottsprohort.com/_documents/tech_sheets/H5150MicromaxMicronutrients.pdf

To modify the recipe above, I would use a handful of that soil and a handful each of Turface (a baked clay granule that is great at holding moisture and nutrients) and crushed granite. In the pic below, you can see the Turface (tan - it's screened to remove fines for a special soil I was making at the time) and the crushed granite. (Disregard the soil at top. It is a soil that I built (no topsoil in it) for my raised beds.)

This is a variation of the soil I use for woody plants. The cactus soil would look much the same, except that I would not have screened the fine particles out of the Turface, and you could have used a smaller granite size (it comes in at least 2, pre-screened sizes & is very inexpensive). You could also add some coarse swimming pool filter sand (silica) to the mix. I also grow nearly all my houseplants in some minor variation on the soil you see here.

You'll note that in all my soils, I try to be absolutely sure they will hold air. It is the most important consideration in any container soil. A poorly aerated soil means you begin your growing efforts under handicap. You can never know your full potential as a container gardener if your foundation (soil) is not sound.

Al

Tapla --- Great info - thanks. Would it be acceptable to substitute powdered kelp/seaweed for the Scotts Micromax? If I cannot find a local supplier for the Turface, can I use the water-retaining polymer crystals instead? Or small cubes of coir? If no, what do you suggest?

Talpa,

What is your oppinion on coconut coir vs. peat. There seems to be quite a bit of it at garden centers lately and being an agricultural by-product rather than pulled from peat bogs it seems to be much more environmentally friendly & sustainable.

While I will admit to having used Miracle Grow potting soil in a pinch - for ornamental containers only - I normally make my own from well-composted horse manure/bedding, peat moss, & sand. I don't really have a "recipe", as I adjust the amounts of each depending on what I plan to grow in it.

I find that plants grow well in Miracle Grow/Scott's potting mixes. Most have fertilizer included (after all it is their speciality) but then again I am not insisting that it has to be organic. Generally, I found the mixes are producing nice plants, and it beat trying to mix your own.

YardenMan - The fish/seaweed, and particularly the seaweed emulsions are good sources of micro-nutrients. I use them, along with chemical fertilizers throughout the grow season. Turface is clay that is baked into a near ceramic state, but it retains excellent porosity, an irregular shape, and holds nutrients like clay does. It is a completely different material than water holding polymers/starches or coir.

Willmetge - I have to say that I haven't grown in coir yet. I will have to try it because I'm frequently asked the same question you pose. What you use is not as important as how it works with the rest of the soil components. If it holds moisture and air when in combination with the rest of the soil parts, and isn't toxic to plants, it will work in soils. I don't by the nonrenewable argument about peat. I get that question in my mail all the time, so I have written this reply:

"Chicken Little would be aghast at your inference!! In my estimation, it doesn't matter much if it's renewable or not, and I refuse to be made to feel guilty about using any form of peat.

Sorry, but I'm not buying the non-renewable lament. In Canada alone, there are more than 270 million acres of harvestable peat bogs. If we make the conservative guess that the harvestable portions of these bogs are 10 feet deep, that means there are probably more than 900 billion cu. ft. available for harvest, just in Canada! That doesn't even take into consideration what's available in Europe, Asia, or places like New Zealand where they also mine peat. Canada currently has mining/harvesting operations underway on approximately 40 thousand acres or about .014% (that reads 14 one thousandths of 1 percent)."
Check the math - it's accurate and conservative. It's more likely that the next ice age will be upon us and glaciers will have covered what's available before we even use a noticeable percentage.
Renewable/non-renewable = moot."

FWIW There will always be naysayers that are totally happy with whatever medium they are using. I have no wish that they change anything. If their soils are good enough for them, they're good enough for me. The conversations that yield the most light are with people who are not happy with their container soils and who are interested in learning more or making the effort to build a better soil. I would offer this for consideration; I have something of an advantage in that I have grow in products like MG and other bagged soils. When I began studying soils many years ago, what I learned caused me to make the switch to some of the soils I share here. I never looked back.

Al

(Applause)

I blend my own soil mixes without any of the science & studied considerations demonstrated in
earlier postings. I have a stash of many ingredients & blend 'em for what I'm potting - tuface,
chicken grit (two sizes), sand, peat, coir, perlite, vermiculite, worm castings and for my outdoor
baskets, polymer crystals. My very favorite off-the-shelf mix is ProMix. Our local Agway sells it
in very large bags. Its got a wetting agent & just feels wonderful.

Tam

Tapla, Tammy --- where do you guys buy the Turface? My internet searches are going nowhere. Again, thanks for the help.

Charlies Greenhouse

You can read up on it at:
http://www.turface.com/turface/index_athleticturf.html
I was unable to find it listed at Charley's - I probably missed it, but if you have no better luck than I, (and I would think that freight would be more than the product) you can call Profile's customer service or fax them (see numbers below). Ask for distributors near you and call them. If they will not sell direct, ask the distributor who they sell to near you. The product you are looking for is Turface MVP.

800-207-6457 cust. service
847-215-0577 fax

This plant is growing in 100% Turface - nothing organic in the soil at all.

And so is this one:

Al

I bought several bads from Charlies a few years ago. Maybe they don't carry it any longer?
Tam

Tammy --- Charlie's - is what they call "pumice" in the orchid supplies section what you have been ordering/using? Is it Turface with a different name slapped on it by Charlie"s to hide exactly what it is?

Tapla --- I called the Turface 800 # you gave me in your 2-6-06 post (Thank you) and believe it or not, they do not have a dealer or distributor within a 50 mile radius of Columbus, Ohio. So I continued my Google search for Turface. I have come across these "turface-like" products that I can order over the internet. If you are familiar with any of them, how do they compare to Turface? Hydroton or Aliflor or DynaRoc. If you are not familiar with them, no big deal. I just will continue muddling along in my Google search and sooner or later I'll find the info I want. Oh, the pains of being a rookie, ha!! Once again, thanks for all of your help.

Y - Pumice is a volcanic rock, Turface is baked (hi-fired clay) - properties are similar. I bet I can find a source in Columbus for you. ;o)

I'm not familiar with the products you listed - mail me links?

Al

Hey, Al. I think I followed you to this forum.

I did a similar google search for Turface-like products (I, too, have had no luck finding the real thing) and came upon a couple of Bonsai forum discussions. Some people seem to have had luck using products that are sold in auto parts stores for spill cleanup in an auto shop or garage, sold under various names such as Oil-Dri, Dry-Zit, Easy Dri, etc.

These products are made of fullers earth, which is, well, fired clay. In fact, I looked at some sold in Auto Zone, and it listed--right on the bag--several additional uses, including use for ball fields (which is what Turface is chiefly used for), in potting soils and as a soil amendment.

I read where many people have had good luck with the material, which is much easier to find than Turface for many people. But I've also read where a couple of people tried it and it turned to sticky mush on them. Do you have a take on these products, Al?

Also, despite living in a very agricultural area (tons of cotton and soy grown in my area, a lot of livestock, as well as a chicken plant down the road), not a single feed store carries chicken or turkey grit. One guy told me that they sell crushed oyster shells, not crushed granite. (I guess being 60 miles from Georgia's barrier Islands could have something to do with that.)

Could the oyster shells possibly work? Anyone tried them?

--Scott

This message was edited Feb 7, 2006 7:47 PM

I'll check the bag to verify its turface! I sure remember it as such and I got it from Charlies several years ago.
Tam

I can't say those products are the same as Turface. It could well be that the difference lies in the firing temperatures, but I can't be sure. I see the mixed results reports on various forums, too. Since I have never had trouble getting it (having a pallet of it delivered in Mar) I haven't had to resort to those other products. If you really want to find it, contact a bonsai club in your area. A couple of phone calls will likely yield a source. I've tracked it down for people that way several times.

I have a friend in Seattle that has mentioned using oyster shells in container mixes, but I have not tried it. Be careful of the salt content if you try them. They would be rich in Ca, and container soils always need it.

Not alota help, I guess. ;o)

Al

Tapla --- Gardening Supply Warehouse (http://www.gardeningsupplywarehouse.com) sells Aliflor (clay fired aggregate beads) and Dyna-Rok (fresh water diatamite rock).
Green Barn Orchid Supplies (https://www.shop.greenbarnorchid.com) sells Hydroton (hydroponic clay rock).

The hydroton's shape is not going to do much for drainage or air porosity. The lava rock and probably Aliflor look like they would. In the first link, that product sure looks like Turface - might even be better? Turface should sell for $8-9 per 50 lb bag if you find it.

Good luck.

Al

RE tapla photo of composted pine bark above:
This looks exactly like "Nature's Helper".