Hard question to answer, Mike.

I don't see that one can really go wrong with either, but the gritty mix, due to it's lower organic content, will retain favorable aeration for longer.

Still, the 5-1-1 mix is no slouch in terms of it's useful lifespan compared to most commercially bagged mixes containing mostly peat or composted forest products (still don't know what that is).

justaguy, I have asked elsewhere in another thread but got no replies.

How many times have you reused a 5-1-1 and grown another successful vegetable or other plant in the same container with the old mix. Al says he changes it out after one year.

Does anyone have any real experience with reusing the 5-1-1 mix for any length of time with annuals like vegetables? I am not saying that it won't last longer --I just wonder if anyone is actually reusing as these ingredients are expensive (as is store bought peat mixes).

At Earthbox 'farm' earthboxes planted in peat-based mix are now on their 14th planting over a period of 7 years though I believe they 'officially' say the mix can be reused for 4 or 5 years.

I have seen it stated in other thread that the 5-1-1 lasts 4 times longer --so are we talking about 16 or 20 years of reusing the same container over and over again--doesn't make any sense.

I do reuse the mixes - up to a point.

With an organic based mix such as a bark based mix what I look at is the size of the bark. Of course, it won't all be the same size so when in doubt I will do a PWT test on it. If it is maintaining much of one then it doesn't get used again. If it is not, then it likely will.

Keep in mind I am only talking about seasonal stuff like flowers and veggies. For longer lived plants I am more particular as the effects of a mix holding too much water/too little air are cumulative. Many longer lived plants and woody plants are also much less tolerant of wet feet that the annuals are (there are always exceptions, of course).

I don't mind a bit of a PWT with some plants such as tomatos. Again though, these are deeper containers such that the roots won't have to deal with the PWT until the plant is larger and using more water at which point it sucks up the water in the PWT fast enough to not be a concern as long as it's minimal.

Now, the above is just 'how I do it', not a recommendation. Others make different choices such as tossing a mix after a season no matter what. It's hard to argue that doing so is 'bad' for the plants ;) It can be hard on the wallet though.

In terms of how long I actually use the 5-1-1 mix for annuals I can't say as I don't have anything that is exactly the 5-1-1 mix (I have cut out the use of peat altogether).

Still, in looking at the contents of some whiskey barrel halves that are 50% turface and 50% pine bark they are at the beginning of year 3 and they are left outside year round. For my purposes with annuals the mix is still suitable for another season, but I doubt I would use it again next year. By that time there will be far too many particles that are roughly the same size as what is found in a 'fresh' peat based mix ;)

In SWC, it's a different world. Generally folks use SWC for the water pig plants ;) These mixes aren't top watered either which compacts the mix squeezing out air spaces. Both these factors combine to provide extra leeway. Also, unless a SWC is top watered or gets a lot of rain (same thing) a PWT should not normally develop. The mix will absorb water up to it's saturation point, but nothing further. It's only after water exceeding the saturation point of the media is introduced that a PWT develops.

I know the EB people say 4-5 years with a peat based mix, but even with bark based mixes 3-4 would be the limit for me for any mix based on organic components. Could one go longer with great results? Probably, I just don't care to push the limits to the point I have a bad season due to the mix.

Anyway, those are my thoughts, for whatever they are or aren't worth.

If peat was such a durable container component, nurseries wouldn't bother with pine bark. When any one particular person or entity 'says' you can reuse a peat-based soil for up to 4+ years, it shouldn't be considered a clarion call for others to follow suit. I could wear the same socks for 4 years, too, but ..... In both cases, I doubt the wisdom of the practice for good reason.

Water retention and aeration are all about particle size. Given the same size particles, conifer barks break down on the average of 1/4 the rate of peat particles. Considering that the pine bark particles are much larger and have a much lower volume:surface area ratio, the bark fraction in containers probably remains as serviceable as peat for much, much longer.

There is no way to avoid excess water retention and lack of optimum aeration in soils that are collapsing (soil science 101), and peat-based soils are seeing serious degradation before the end of a single growth cycle. This isn't simple conjecture on my part, this is all researchable information you can look up for yourself.

I choose to add my bark-based container soils to the compost pile or add them to gardens/beds because I feel that even a soil that outlasts a peat-based soil several times over is still BETTER if replaced annually, and there are other reasons I replace it that are not structure-related. I've mentioned many times that when I discard soils after a season, they are still more plant friendly than almost all peat based soil out of the bag. I'm usually ALWAYS careful to point this out in the hope it will avoid confusion.

The part that doesn't make sense is found in the idea that someone claims they are using the peat well beyond the point where the original fraction has turned to soup. Peat particles are small to begin with, and they break down much faster than conifer bark. This isn't a MO I would suggest for either SWCs or conventional containers.

Al

I am well aware of the many benefits of PB and pine bark fines in the horticultural industries including greater longevity over peat.

I am just surprised no one is reusing mix for a much, much longer time frame. I can't imagine plant quality would suffer that much over (possibly) many years of use.

I read years ago that pine bark fines are widely used in some greenhouses. I have not experimented much with pine bark fines , not because I don't think it would be superior in some respects, but because it is VERY hard to find while soilless peat based mixes are everywhere.

I have some large containers that are 'rejuvenated' and reused year after year but smaller ones like EB I dump into raised beds or into other mixes but based on EB research obviously that is not necessary.

I am mainly interested in repeated use of mixes on yields of tomatoes so I will do some experiments. I would expect pine based mixes to be on top of longevity (total inorganics require too much watering). The pine bark I have access to and have used in the past in bromeliad mixes is pretty big chunks--smaller, semi-composted fines may be a great medium base but it will take a special order someplace for me to locate it. (Farfard's soil conditioner is not available.)

I am mainly interested in repeated use of mixes on yields of tomatoes so I will do some experiments.

It all boils down to particle size which determines how well the mix drains and the plant. If the plant is a water pig a little perched water table is rapidly sucked up then the plant will do fine.

Al has long been a champion of well aerated mixes, but I suspect this message is largely lost on those who primarily grow tomatos and hot peppers. These are plants that are very adaptable to a variety of conditions and will do well almost in spite of the grower.

I suppose if one were really anal and measured total yield per plant and stuff like that a difference might be seen, but for more established plants in a less than optimal mix these guys tend to do just fine.

Can you grow tomatos in a peat mix for 5 years? Probably. The only issue would be young transplants in the early season, but if they make it to larger size/summer they will likely do just fine.

There are other plants that seem to buck the rules. I have grown canna in, literally, containers filled with clay subsoil with no drainage holes flooded with water. It's important to not subject the tubers to those conditions when it is too cool for sprouting, but once they grow they do fine in such horrid conditions due to their adaptability.

Are such conditions optimal? No. Will they 'work'? Yes, for some supremely adaptable plants. Being able to adapt and cope aren't the same as thriving though.

Here is my philosophy when it comes to container media:

Why subject all plants to conditions that only a few can tolerate? Why not subject all plants to conditions they can all thrive in?

More than likely if all you ever wish to grow are tomatos and you grow them or buy them at a good size you can stick them into 10 year old soup like potting mix and they will at least do OK (they might die as well, just depends on the year). They are the exception, not the rule.

I think JaG hit on something that's always been fairly significant part of my offerings, and that is optimization. I've never said you couldn't grow in this or that. I may point out the probable shortcomings of a particular soil, but I never say you can't grow in it. I often say you can grow in a bucket of marbles, if you want to stand over it and water every 5 minutes. The same is true of a heavier soil - if you want to water in sips with distilled water & can devise a plan for ensuring soluble salts levels don't get too high.

The point is, I've always been about two things - optimizing and simplifying. If I am a help, it's usually to those who wish to optimize growth or improve performance of their plantings. I'm little help to those content with the way things are. To many, me included, only a little improvement is a lot - kind of like using premium fuel in your car so you can squeeze out just that little bit of extra acceleration or top end speed - only in this case, the 'little extra' ends up being cheaper when you make your own.

I figured what I had learned about soils could be helpful to others. I registered with GW in '02, and in '05 I posted the first soil thread. I'd mentioned the importance of aeration time after time, and how bark-based soils could be so much easier to grow in and more plant-friendly, and received a LOT of criticism and ridicule for trying to upset the apple cart. Eventually, a few started to see that what I was saying made sense & tried it. Now, there are at least six people growing in bark-based highly aerated soils - and I think at least 2 in the gritty mix. ;o)

Some people have made very large advances in the amount of satisfaction they get from their growing experience as a result of changing to a more forgiving soil. Others have incorporated the 'aeration message' into their way of thinking about soils and have been pleased to have done so. The simplicity part comes into play because it's difficult to over-water a free-draining, well-aerated soil - you really have to work at it. That the soils I use have only 3 basic ingredients each, is also a form of simplicity. No .... not as simple as opening a bag, but those happy with simply opening a bag are not the ones I'm trying to reach anyway.

The satisfaction isn't necessarily commensurate with the size of our forward strides. More often, it's in the perception of our progress. The people I care the most about are those who are happy to be moving forward and who are willing to do just a little extra to ensure that their progress is steady (no matter if it comes in leaps and bounds or that it comes in baby steps) - they're all kindred to me. ;o)

Al

justaguy,

"you can stick them into 10 year old soup like potting mix and they will at least do OK "

thanks for the comments however 'OK' would not be acceptable to me. I am only interested in mixes that maintain their structure enough to produce exceptionally high yields or at least close to the high yields experienced with brand new mix.

Also as you know many, many people simply can't change out these expensive soilless mixes and yet they want (and need) to grow vegetables in limited areas. Costs close to $14 to fill an Earthbox with peat based mix which wicks beautifully and if it can be used multiple times all the better.

I use both mixes, depending upon the plant and the container. For my succulents,
I prefer the lean, gritty mix. After root-pruning and re-potting several Jade plants in
the gritty mix, I found that the roots firmly anchored the plant in the medium within
two weeks or so.

I also like the fast-draining gritty mix for over-wintering plants - such as peppers -
which don't like "wet feet."

Mike,
I re-potted a dwarf gardenia in a mix similar to the 5:1:1 a while ago, and it seems to be
recovering from the insult I did to its peat-packed roots. I also have maple, osage
orange, weeping willow, olive, oak, incense cedar, and cryptomeria in bark-based
potting mixes. Lately, I've been adjusting the amount of pine bark fines (instead of
peat-moss) to get the right amount of moisture in my mix.

Josh

Are tomatoes the only vegetable that is a water hog? It sounds like some others like a fair bit of even water. Peas, radishes. Anything that does its peak growing in mid/late summer? (other than peppers)

I've figured out that my oregano and basil died last fall due to uneven and over watering with a less than ideal soil. lack of light and being next to a cold window probably didn't help.

I'm not sure what to do with the lettuce, other than it should not be going in 4" of soil.

So my herbs are going in something like a 5-1-1 and my tomatoes/eggplants are going in SWC's with the mix recommended at earthbox and a cover. Haven't quite decided on the peppers.

I'm not sure what to do with the lettuce later in the year, other than it should not be going in 4" of soil of any kind.

Dahlias like the 5-1-1.

Alice

I'm not sure what to do with the lettuce later in the year, other than it should not be going in 4" of soil of any kind.

They do fine for me in 5" :) Just a simple bark based mix in a trough shaped SWC.