Marc, I totally 'get' why you don't like the appearance of perlite. You are certainly not alone in that. If only it weren't white, right? But the benefits of perlite are so important that I think you should try to overlook whatever it is about its appearance that bothers you.

I dump all of my used potting medium straight into the veggie garden where it will eventually be worked into soil. Perlite is a one hundred percent natural product (though it goes through a man-made process) which has no negative qualities. The fact that it doesn't disintegrate is one of perlite 's benefits. Those many positive physical attributes that it adds to a container mix are much appreciated in my nice, porous garden soil.

I don't use the mixes you've mentioned, and have always opted for one of the several Fafard Professional Heavy Weight mixes. None of them have a great deal of perlite but do have some. I keep a big bag of perlite on hand and often add it to the Fafard. No matter how much of that white stuff is in the medium, it'll end up in the veggie garden.

Perlite does break down. Just ask some cactus people. That's why they don't like it.

My 5-1-1 gets mixed into my garden beds. I desperately need the organic matter.

I have related questions:

1. Is it okay to re-use the same soil year after year? I thought about rotating crops. I've planted sweet potatoes in some of my containers.

2. I had a fungus on my bell peppers and tomatoes this year. Is there something that I can do to salvage this soil while eradicating the fungus?

3. How does everyone remove the roots and plant material from the soil each season?

The Gritty Mix, depending on your actual ingredients, is partially comprised of inorganic material that can be sifted out and re-used. The organic portion... the bark and whatnot, will have begun to break down, to decay and decompose after a couple of years. Once sifted out, I just dump the bark/organic/decomposing portion on my garden beds outside. I use the inorganic portion in making new medium with fresh fir bark, fresh coarse perlite... mixing in the salvaged granite bits or whatever else I saved.

Sometimes, I just dump the whole pot of old mix on the beds, knowing that all those larger-than-silt particles are good aeration for my garden beds.

I no longer use a pre-mixed, bagged soil for my container growing. I've found its tiny particulate to be detrimental to good drainage and aeration, two of the most important things in decent root health. And root health determines plant health.

I think one thing we have to keep in mind is that there really is no one-size-fits-all when it comes to container growing, and a medium that works in one environment and/or climate might need to be upgraded or changed a bit to work well in another area. Some growers might be able to salvage more in inorganic ingredients when changing out mixes in re-potting because they are able to use more in a mix, while someone else might require more moisture retention, and might use slightly different ratios of ingredients, or different ingredients, altogether.

I use various screen sizes to remove different items. The old roots are usually easy to remove by hand, and few tiny pieces left behind doesn't usually harm anything, I've found.

I don't mind perlite, at all... it's light in weight, and I don't think it detracts from anything, even in garden beds. I'm not really after the aesthetic in mediums... I'm after the working abilities.

As I said, I don't use a bagged, fine-particled soil... but if I did, I wouldn't reuse it year to year... it's about shot after one season. (Personally, I think it's shot before ever poured from the bag.)

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

No one is more thrifty, ask my wife, than I am. I have tried sifting and reusing the inorganic portions of my professional potting mixes. Using my labor to save my money, and I have given up. Not because I have more money, but simply because the saved mix does not do the job. It took several years to prove to me, but the salvaged mix, is no longer salvaged. Al

Just a teensy addition to jodik 's good remarks......not all packaged potting mixes are 'cut from the same cloth', so to speak. Though most of them are not something that I could ever be happy with, there are some out there that exceed my stringent requirements.

This is very true, Rhizo... all bagged mixes are NOT created equally.

I was speaking in general of the industry standards... those being the Miracle-Gro, Schultz, Hyponex, other common brands, and/or generic bagged potting soils... anything comprised of fine particulate, peat, and mostly decomposed yuck. You know what I mean. :-)

I have yet to see a decent brand like Fafard offered anywhere within a large radius of where I live. Ordering it in would cost me too much, so I either use what the industry offers... and has offered forever, to the detriment of many a plant... or I mix my own. And to my surprise, it's not only reasonably priced, it's fun! And, it allows me to custom mix for the plant types I'm growing and where they'll be situated.

It's funny how science and industry rarely cross paths, isn't it? One of my pet peeves... the idea that ethics has all but disappeared from capitalism. But I digress...

You're absolutely right... there are a few very good bagged mixes on the market, but they're few and far between, and they're rarely available at the normal places the average grower might shop.

I knew that's what you meant, jodik.....just thought I'd clarify. :-)

I totally agree that the Fafard professional mixes are not found on the shelves of retail garden centers or nurseries. But I have never had a problem getting a garden center to special order a few bags for me but maybe that's because I know exactly what I'm asking for.

The professionals have ready access to the Fafard products....that's how I first got my hands on it over 20 years ago. It's too bad that high quality bagged potting mixes are so few and far between.

Perlite does break down. Just ask some cactus people. That's why they don't like it.

Really? Somehow I question that. Perlite is a siliceous rock that has been heated to expansion. It is no more likely to "break down" than any other rock type. It does come in various grades and the fine grade could quite easily vanish into a mix, thus appearing to break down or disappear. Are you sure you don't mean vermiculite? Vermiculite is notorious for compacting or breaking down once fully saturated.

I grow a lot of cacti and succulents myself, custom mix my own cactus soil and have never had an issue with perlite breaking down or disappearing.

No I mean perlite. I have heard more than one cactus geek warn about using perlite saying that after many years a perlite rice cake forms on the bottom of the pot and can kill the plant. I've seen the beginning of this in pots with large sifted perlite as well, so little fines that could be settling. It is also subject to mechanical breakdown as the heat treatment makes it very friable and it is recommended to not keep it in a mechanical mixer for long periods of time for that reason.

Well, that clears it up! "Many years " is too long for any container mix to be in constant use. The physical activity of an active root system is enough to pulverize some perlite over "many years ".

Considering perlite is glass, how "many years" we talking? 1000? :)

Not fond of perlite, but use it. Have to agree with rhizo.. "many years" is too long.

JoJo

The perlite 'rice cake' at the bottom of the pot is probably there because toe soil's organic fraction (probably peat) has largely broken down and been used by the plant or gassed off, leaving nothing but the perlite ...... which probably hasn't really broken down - it was already too small to start with, and now it's getting blamed for the growers years of neglect.

I see it over and over, when many growers don't understand the real reason for things, they make up some science that seems to fit their observations, rather than research what's actually going on. This leads to a lot of misconceptions and the passing around of a lot of misinformation. I'm not just talking about this particular topic, but gardening as a whole has hundreds & hundreds of myths that keep getting passed around because we gobble up a manufacturers advertising hype & treat it as fact, or make up the science to fit our observations, instead of checking what we THINK we're seeing against settled science to see if it fits.

I usually don't reuse soil from year to year. This year, I put 3 tomato plants in 18 gallon containers that were still filled with last years soil and topped them off with fresh. I made sure that each plant I potted in the used soil had a counterpart in fresh 5:1:1. The plants in all 3 of the containers with old soil were very noticeably smaller and had fewer fruits, even though I watered selectively - on an as-needed basis. I had no disease issues, but the plants simply did not perform as well. I attributed that to the fact that the used soil, in a more advanced state of decomposition, supported a lot more perched water than the plants in fresh soil, which affected growth/vitality/yields. I still had more tomatoes than I could use, so no harm done, but if I only had room for a few plants, I would have been disappointed, given the productivity I'm used to.

I usually spread old soils first on raised beds that need topping off, or the gardens, and sometimes the compost pile.

Al

Well said Tapla. People say things even if it is not explained by science. Then when you try to tell them the real science they get mad that they cant understand it like you do then further believe the hype they are following. I admittedly used to be one of them :)

In my experience, perlite floats to the top, so I'm not sure how it ends up on the bottom of a pot... though using the same soil for years might account for that. I don't know, as I don't use the same medium for more than 3 years, and that's maximum!

Speaking of perlite... I just made and used a batch of the Gritty Mix, and I usually add coarse perlite to it. I completely spaced adding the perlite portion! It's okay, though... it still looks good, and I'm sure it'll be fine for a little while. Me and my poor memory! ;-)

Anyway...

"...gardening as a whole has hundreds & hundreds of myths that keep getting passed around because we gobble up a manufacturers advertising hype & treat it as fact, or make up the science to fit our observations..."

Once we get away from perpetuated myth, industry standard, and we actually dig into the simplified science and basic physics of plant growth and container gardening, the difference in results gained can be so amazing. Once my eyes were opened, I was hungry for more information! And now, I know what I was doing wrong all those years, and I understand the processes of growing, both in containers... and in gardens... which are completely different environments!

Have a nice day, everyone... and don't forget to VOTE! :-)

Today I went to the gardening shop. I found perlite for roses it is not very expensive but perlite for vegetables are more than double times expensive from the perlite for roses. What is different between these two perlites types. I asked to the shop but they cannot explain very well. My question here is a bit different from the subject, so sorry.

I'm pretty sure that these people from the Huntington weren't making up science to fit their observations, Al. The person making stuff up is you withyour imaginary potting medium composition to fit your assumptions. I have found small pieces of perlite in pots after having sifted and washed the perlite. How do you explain that without breakdown or ad hominems?

Many years is too long? I'm sure the folks at Disneyland might disagree. You might want to qualify that with a specific mix. Too long for pumice? Probably, but then why is that if not because of being broken down? Besides, the original issue dealt with adding medium to garden soil and an aversion to that because perlite doesn't breakdown. Something so friable as to be easily be crushed with finger pressure or mixer agitation will certainly breakdown in a cultivated garden bed or especially due to freeze/thaw cycles which can breakdown concrete. Or course we are talking mechanical breakdown not decomposition.

But if someone wants to present some 'real science' proving that perlite doesn't breakdown, I would love to see it. For some reason, I think that claim probably falls in line right next to the 'sand doesn't hold water' myth.

Settle down, Tiger. My comments weren't directed at you. I was partially referring to the "cactus geeks" you referred to, and their observations, plus the general tendency of many growers to make up explanations that seem tenable to them but crumble under even a cursory examination.

There was certainly nothing implausible about my explanation, in fact, there is an extremely high probability it is exactly how those 'rice cakes' happened to appear at the bottom of the cactus geek's pot after so many years. Scheesch!

Al

Posted by nil13 z21 Mt. Washington L (My Page) on Tue, Nov 6, 12 at 18:54

"Or course we are talking mechanical breakdown not decomposition. "

Yea so everything you just said makes no sense then...

"But if someone wants to present some 'real science' proving that perlite doesn't breakdown, I would love to see it. For some reason, I think that claim probably falls in line right next to the 'sand doesn't hold water' myth."

Perlite does break down, it just takes thousands of years. :) Is that 'real enough' fot ya'? Perlite is 'glass'.

What does Disneyland have to do with this? How does it fit into the picture?

JoJo

They grow trees hydroponically in containers for long periods of time at disneyland.

What doesn't make sense to you about mechanical breakdown versus biological decomposition MG?

That perlite is glass just means it's brittle. Brittle things break easily. It also has a lot of little spaces in which a plant root could grow and exert shear forces unlike say a glass bottle.

I also realize there is an error in my post above. I wrote pumice instead of perlite. Sorry about that.

It does! I do agree.

That is why I am saying "that says it all" and what else you said is not the case, or makes no "sense". I more or less stated that wrong. Like you say it is mechanical breakdown not decomposition. So you answered your own question! :)

"Posted by jodik 5 (My Page) on Thu, Nov 8, 12 at 12:22

It must be autumn again... and post election, to boot... that's one explanation, in my opinion. "

I see. That says it all. Autumn has all to do with biological decomposition :)

Hello forum members, would like to know if self watering pots can be used with gritty mix or 5-1-1 mix's; because i would like to grow boston ferns and have read they like very moist medium and reading that self watering pots are good for them , and beeing the gritty mix or the 5-1-1 mixes good aeration types mediums, seem a good couple : ); so wondering if can they be used together to benefit the fern ?