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Grow Medium

Posted by TheMasterGardener1 none (My Page) on
Tue, Nov 22, 11 at 14:16

Hello everyone. This coming season I will be growing a large container garden. I want it to be cost effective and get more out of the garden then what I put into. Growing everything from greens to tomatoes, I need a lot of containers which I will pick up at a local nursery for free hopefully. I will be doing some plants in the 5-1-1 but I have to sift out mulch to get the fines. I cant find sifted bark fines anywhere so i just get pine mulch. Here is the big question, can I use the mulch and peatmoss without perlite as a grow medium, provided I take some huge nuggets out and ballance ph with lime? I want a very economical mix that will perform just as well as store bought potting mix. Thanks!


Follow-Up Postings:

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RE: Grow Medium

Include the Perlite, since Perlite is cheap.
Peat-based potting soils can be used as a substitute for peat moss,
so if you have any extra potting soil you can save money that way, too.

When you say "pine mulch," does that mean there is sapwood included?
If the product includes more than, say, 10% sapwood, I would not use it.


Josh


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RE: Grow Medium

I agree with greenman, perlite is relatively cheap, especially considering it only makes-up roughly 15% of the 5:1:1 mix. Leaving it out altogether would have a big impact on porosity and drainage.

With regard to locating pine bark fines, I've found it at all the major big box retailers in my area - though they generally don't have the "right" stuff all the time. I've even found a fairly acceptable product at the K-Mart. If you can find the larger pine bark (sometimes called mini-nuggets) you can always rent a chipper/shredder to grind them up a bit. I did this recently and came away with a very nice grade of fines. Finally, some of the tree/shrub nurseries use a container mix that is predominately pine bark. If you have one in your area, you might inquire if they'll either sell some or suggest a local source.

Good luck!


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RE: Grow Medium

Depending where you're located, pine or fir bark can often be found in bulk through orchid or bonsai growers. If there are orchid or bonsai clubs in your local area, you may want to ask members if they know of a place to locate a bark product in a good size.

Sometimes, as Josh states, you will get lucky at a big box store, and they'll have a plain bark mulch in a decent size that may only require some screening to remove larger pieces and dust.

It can take a little research to locate suitable products, but it's worth it. There's also a thread here on the first few pages called Gritty Mix Items by Location and State, or something close to that. It may be a big help in locating bark in your area.


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RE: Grow Medium

Thanks all.


Yes I use the one from K-Mart pine bark product that has no sap wood, its easy to sift, plus I can use the larger chunks for mulch or try with larger trees in containers. I can see the pine is even cheaper than or about the same cost as the peat is before I sift it (4bucks@ 2 cu ft bag), coming out to about 4 bucks a cu ft sifted(1/16"-3/8") which is not bad after all said and done. I will do most of the garden in 5-1-1 for my larger plants, and a peat based mix of 8-1 peat/perlite for my smaller containers, comparing them to the peat/bark mix which is the cheapest mix but has the least air porosity. Well thanks for the responses and I will update how each mix did.


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RE: Grow Medium

8 parts peat to 1 part perlite?
You might as well not add the perlite at all.
You'll just be wasting it, since you won't be gaining any of the benefits of perlite at that ratio.
If you want perlite to improve the peat, you'll need to go 75 - 80 percent perlite.

Good luck.

Josh


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RE: Grow Medium

Why do I see alot of store sold soiless media that is 85% peat and 15% perlite? I understand all perlite with a dash of peat is ideal air porosity but thats not what you get when you buy medium. I am sure the perlite helps a little or these huge companies would not be making mix's like the 85/15 peat/perlite.


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RE: Grow Medium

People buy it, so they make it. The plant's best interest is certainly not in mind.
With the addition of perlite, folks are lured into the false notion that the soil has drainage.


Josh


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RE: Grow Medium

Josh; I am no expert but I take great exception to you on the percentage of perlite. Quote "If you want perlite to improve the peat, you'll need to go 75 - 80 percent perlite." To me that is backward. Are you sure you don't have them reversed? I have used 10 percent (store bought potting mix) and many times add another 10 percent. It keeps the container mix light and fluffy. that is my standard mix. I just don't want the newbys and beginners to start off with the wrong idea.


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RE: Grow Medium

I think that's part of it, greenman, but there has to be a more commercially-motivated reason. After all, 95% of the people buying potting mix don't know/don't care about drainage. They'll buy WHATEVER is in the bag without question. The concepts put forth by Al are similar to those proposed by many of the research-based studies on container culture. In other words, the information is out there and available. So, with that in mind, why not compose a "proper" mix? I don't have the answer, but my guess is that it's cheaper to make and/or cheaper to transport (i.e. lighter in weight). Another thought is that the peat-heavy mixes, although they don't provide optimal growing conditions, will provide the largest majority of growers (i.e. the "general public") with the best chance of success considering the expected neglect and inattention.


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RE: Grow Medium

I don't want folks starting off with misinformation, either, which is why I must correct you.

Take exception all you want, Colokid, but facts are facts. I certainly don't have the number backward.

To use Al's analogy, adding Perlite to peat is like adding Marbles to pudding.
How many Marbles would you have to add to pudding to begin seeing a drainage benefit
from the marbles? Answer: the significant majority of the mix must be Marbles.

In the peat, the Perlite will reduce the overall water-holding capacity of a mix....
essentially, the Perlite is displacing moisture. But that doesn't necessarily improve drainage -
again, not until the significant majority of the mix is Perlite.

Many folks make the mistake of assuming that a soft-textured soil (light and fluffy)
is also well-aerated and fast-draining. Porous, open, fast-draining soils are not "soft" -
they are structurally durable, fairly uniform in particle size, and gritty.

Fortyonenorth, the bottom line is money. As you mention, peat is cheap (and cheap to transport).
The cost of transporting proper ingredients, like bark and grit, would cut into the bottom line on
the transport end, as well as the longevity end. If you provide a superior mix to a customer,
that customer might not replace his/her mix next season. Heaven forbid you *teach* a customer to
make his/her own mixes...for in doing so you would cut the potting soil producer out of the loop.

If anything, peat based mixes ensure that plants will suffer and that unwitting customers
will be back for more. Sadly, many of those customers will blame themselves for what is
primarily the failure of their mix.

No amount of Perlite added to peat will take the place of a properly made mix.


Josh


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RE: Grow Medium

Gosh it's sure nice to get educated. After a degree from an ag college and over 60 years of making my living from growing things I now find out that all I had to do was believe every thing I read on the internet.


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RE: Grow Medium

I live in an area of commercial wholesale nurseries that propagate and ship all over the country. For their own use on their own plants, I do not know of a single one that uses a peat based mix. Their plants are being purchased and used by landscape contractors and sold by retail nurseries. A bark based mix will hold up and not turn into soup, and if the plant is not sold within 3 months it will still be good at the end of the season. Al


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RE: Grow Medium

Well I see I have quite a few responses. It looks like it has turned into a peat vs pine bark debate ;)

All in all bark and peat are two different things, peat is made for water retention, and bark is made for drainage. I understand the 5-1-1 will be best, but I will be doing a side by side comparison of the mix's. I think in my small 5" pots the peat based mix will do better because of the size. It seems a larger container with the peat based mix really turns into a block of muck when watered. Thanks for everyone's input.


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RE: Grow Medium

I was at a friends nursery here in Southern California and I was checking out what was in his pots, I'd say most of the plants are potted in a mix of sand, bark, perlite, some sort of porous rock/clay and very little peat, I mean a very small amount of peat. This is why they water all the time, and when I buy a plant from him and take it out of the pot the mix comes off the roots really well, it's very crumbly. I was going to ask him about it because I was looking for Haydite, but he was on vacation. My native plants I get from Las Pilitas nursery also come in a very friable mix.

On the other hand my favorite nursery (which I buy many plants from), if I'm not careful about watering them while I'm waiting to get them in the ground I can drown them. The soil they use is mostly peat and a little perlite and it stays very wet and sloppy for a long time.

Jerry


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RE: Grow Medium

Colokid, you're never too old to learn something new.
Misconceptions can impede new learning, so it's best to disabuse ourselves of these horticultural myths.

Master Gardener, there are actually folks who claim that bark holds more moisture than peat moss.
Bark, however, has structural integrity that the pre-collapsed peat moss particle does not.
I really think you should just fiddle with the 5-1-1 mix - which, as Al says, is a "starting point."
I would keep the Perlite fraction the same, then reduce the bark by one part or increase the peat
by one part, just to see what the moisture retention and texture of the mix feels like.

Calistoga (Al) has modified these mixes to great effect, tailoring the mix to his climate.

(By the way, I'm glad your bark mulch is free of sapwood. That's a serious score!).


Josh


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RE: Grow Medium

  • Posted by tapla z5b-6a mid-MI (My Page) on
    Sat, Nov 26, 11 at 12:52

FWIW - I agree with Josh. You can't add small fractions of perlite to fine ingredients like peat, compost, coir, sand, topsoil, or other similarly fine particulates and expect the outcome to be improved drainage (flow-through rates) or aeration. What might happen is the o/a water retention could be decreased, but until the perlite becomes the significant fraction of the soil, there will be no notable difference in drainage or aeration.

What happens is the fine particles simply filter into the volume between perlite particles, leaving the ht of the PWT (the most significant consideration) and air porosity the same as it was before the perlite was added.
On the other hand, if you STARTED with a large volume of coarse particulates (like pine bark or perlite) and added enough fine particulates (like peat or compost) to ensure a level of water retention you can live with. You WILL have a free-draining soil that is well-aerated and supports little perched water.

This concept is very easy to visualize in the mind's eye if you simply picture the example Josh offered of adding large particulates to pudding. A handful of marbles or perlite or pine bark added to a quart of pudding just doesn't do anything for aeration or drainage. In the same vein, adding 10% perlite to a peat based soil will have the same effect, which is virtually none - other than for the fact that because perlite has no internal porosity, its volume does reduce o/a water retention. This IS a benefit, but not the significant benefit we look for and are realizing when we build durable and well-aerated soils with their primary fractions being large (larger than .1") particles.

No one is trying to get anyone to change anything they are happy with, but there is a lot of basic science that can be applied to determine what is and isn't a good soil choice based on the needs of the plant, not the wants/wishes of the grower. What Josh said is both technically and practically correct.

Al


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RE: Grow Medium

I don't believe Josh is suggesting anyone actually employ a mix of 75-85% perlite. It's just an example taken to the extreme to illustrate that adding course ingredients to a 'dense' mix will not improve drainage unless you add a whole lot.

I mostly use the 5:1:1 now, but there are many situations where plain old peat-lite mixes work just fine. As evidenced by the many threads here, there's a lot of effort expended in identifying and preparing bark mixes prior to use, e.g. finding, sifting, screening, etc. If one were to put that much effort into locating the ideal moss peat (e.g. long-fibered, etc.) and then sifting to remove all the dust and small particles, I imagine you'd have a pretty decent starting point for a peat-based mix. Unfortunately, with most pre-packaged mixes, "well-crafted" is not what you're getting.

I've included a link to a very informative article on container media. I'm sure this has been referenced before in this forum - it echoes much of the advice proffered by Tapla - but I've used the information to great benefit.

Here is a link that might be useful: Container media


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RE: Grow Medium

I read that article you linked us too and I thank you.

I laud people like 'Al' and 'Josh' that care enough to share their expertise and in showing us HOW to make these wonderful mixes that not even that article would tell us. There was no recipe. That would be too easy.lol

I use the 5.1.1 mix and the gritty mix solely on my prized plants with very gratifying results. I must tell you that I only know one person here that has shown me his success and secret when many claim to have years of knowledge behind themselves, and yet have not even come close to helping me to succeed as 'Al' when it comes to making the best mix I have ever known..

Thank you Al, and to Josh, for taking the time more so than I should, to help many here that have been left in the dark and for helping us to dispel misconceptions and old horticultural myths..

Mike


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RE: Grow Medium

Let's look at it from an industry perspective... a business exists for what purpose? To make money. Repeat consumers supply that money, so providing them with products that last long periods of time is not to their advantage. Teaching customers how to mix their own mediums and how to lengthen the lives of their plants will not add to the bottom line. In the interest of profit, industry offers us what keeps us coming back again and again.

A lot of generally circulated and accepted information on growing potted plants is either not entirely true, or saturated with misinformation and myths, as Mike states... and most weekend growers will have a hard time separating fact from fiction. There are many variables to growing healthy containerized plants, but the foundation is using a good medium.

We generally tend to be trusting of the gardening industry, and without a thought, we accept that peat based, fine-particled soils are what we need.

The idea is incorporating basic science and physics into our growing... by learning what purposes a medium serves, how and why a medium works in a container environment, how water moves through soils, and what basics our plants need to have healthy roots... because without healthy roots, the plant can't be healthy.

Let's not forget... we're not talking about growing in the ground, which is vastly different than growing within the confined space of a container. In a container environment, WE need to control what happens, because Mother Nature doesn't offer much help in balancing the environment as she does in the garden.

Josh and Al are correct... and their information stands up to scientific and physical fact. I, too, use a larger particled, grittier, fast draining, mostly inorganic, structurally sound medium... and I have had excellent results since learning a few basics.

Al's article on "Container Soils - Water Movement & Retention" is a very informative lesson in basic container growing, and I'm so glad I found it!


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RE: Grow Medium

Thank you, Al, Fortyonenorth, Mike, and Jodi!

I think we all want what's best for our plants, and if new information comes to light that will
improve our growing/gardening experience, I think we'll be the first to evaluate and possibly
implement the new techniques. I certainly won't cling to an ingredient just because I used it
last year or for the last thirty years.

Fortyonenorth, in very rare instances I have actually used high percentages of Perlite.
When I froze one of my prized Jades, I didn't want to take any chances with compromised roots in
a damp mix - so I screened a large batch of Perlite and then added small amounts of screened
fir bark, pumice, and quartz grit to the Perlite. Two years later, after the Jade recovered,
I put it into a more reasonable mix of bark, perlite, turface, pumice, and quartz.


Josh


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RE: Grow Medium

Let's ask ourselves... what purposes does a medium serve?

Well... it serves as anchorage and support for the plant, a catalyst for moisture and nutrition to the plant, and it has to allow for a decent exchange of fresh oxygen to the roots and gasses taken away from the root zone for healthy root function/metabolism/growth. So, those are the basic functions of a medium, or soil.

When the particles that make up a soil are too fine and condensed, they certainly aren't providing for everything that keeps a root system happy and healthy. Because the medium is the foundation of a container planting, it works better if it can maintain its structure and aeration, and its ability to drain well without compacting. The larger the majority of particles, and the more inorganic, the better this all can happen.

I've borrowed from what Al wrote on the subject... link to the original article below... and everything he conveys through his writing is logical, and makes perfect sense from a scientific standpoint. It all stand up to the test of science and physics. Unfortunately, these aren't the normal things we learn from commonly circulated gardening information.

What we do seem to pick up as new gardeners are a mixed bag of opinions, myths, and ideas based on experiences that may or may not have been successful, or may be from a viewpoint that doesn't match up with our own growing climate and environment. And the industry, you may note, does nothing to dispel these myths and bits of misinformation. But why should they? They profit tidily from leaving everything as is.

For those of you reading and looking for some factual information on container growing, written in layman's terms, I offer the original article that has gained Al such a mass following and the amount of respect he gets...

And let's keep in mind... we're talking about growing plants within the confined space of pots, and not the garden... which is a whole different animal!

Here is a link that might be useful: Container Soils - Water Movement & Retention XIV


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RE: Grow Medium

I am so glad to hear from everyone, a ton of good responses and great info. Anyone feel free to keep adding to this post please.


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RE: Grow Medium

"I don't want folks starting off with misinformation, either, which is why I must correct you. "

"Colokid, you're never too old to learn something new.
Misconceptions can impede new learning, so it's best to disabuse ourselves of these horticultural myths. "

^I see a lot of advice given^. It is easy to see it is NOT based on experience :)


"I don't want folks starting off with misinformation"

Low porosity heavy mixes are easier to grow in and provide a large buffer for ph. A reason why I use potting soil even after trying many soilless mixes.

All grown in promix bx mixed with a little compost.

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RE: Grow Medium

I just want to make this clear to many others on here because I have learned countless information from Tapla, Greenman, and others.

My point was- Many new container gardeners, including myself, may find it hard to grow in soilless mixes.

I do understand that using a soilless mix is taking your container gardening to the next level so forgive me if I am behind. Many come here for advice on how to grow healthy plants and I agree using a mix like the 5-1-1 and providing your plants with nutrients would grow a much healthier plant then if grown in a low porosity potting mix. Again,I just want to make that clear to many others on here because I have learned countless information from Tapla, Greenman, and others.

I would never say to add compost to a mix even though I did just to make my mix more like a potting mix. If I have a self watering system of irrigation I could use a soilless mix, but my container garden is far from the house so watering is not easy. For house plants I only use soilless mixes and would prefer a gritty mix or something that will last 5+ years.

I want to some day have a irragation set up so I can produce all my crops in a soilless container set up using a grow medium like the 5-1-1 which I have had outstanding results with.

Thanks.


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RE: Grow Medium

I will disagree about 5-1-1 being only for more advanced growers. When I first started using containers awhile back (although I was experienced with soil and hydroponic), I originally used peat based soils and had all kinds of issues as I couldn't seem to get the watering and fertilization just right. I'd have root rot, then I'd overcompensate and end up hydrophobic. I'd end up with salt deposits and deficiencies. Peat has to be watered "just so" to work correctly.

I finally discovered 5-1-1, and all my watering and fertilization issues went away. It has been a breeze growing things in 5-1-1, and I have never had to worry about moving plants out of the rain. I have less pests. I don't get a crust on top. It just works. Until you try it, you won't realize just how easy it is to grow in containers.

You've said on many threads you have learned a lot on this forum from Tapla. Until you are using one of his mixes, you really haven't learned anything...


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RE: Grow Medium

Yea I have used the 5-1-1 on a cherry tomato and it grew groups of tomatoes on top of each other!!!

I should get a pic, it is just amazing!!! The 5-1-1 is going to give you the same results as hydroponics as far as root growth and yield.

Next year I am going to set up tables and will be doing a soilless garden outside. I will for sure use the 5-1-1. I have some bags of pine bark aging right now :)

Thanks for your advice. i just like trying to find an advantage of potting soil and the buffer for fertilizer/water,ph,ect... is the only thing i can come up with.


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