Shop Products
Houzz Logo Print
jay_part_shade

100% Synthetic Potting Mix?

Hey guys, I have about 50 plants in the 5-1-1 mix and I'm liking it.

That said, I'm thinking about a 100% synthetic mix. I'd like to replace the bark and peat with something that doesn't break down. I use air-pruning pots and grow mostly fruit trees and some vegetables in sizes up to 15 gallons. Because I don't need to root prune, I'd like to leave the trees i the mix indefinitely and not have to worry about the bark breaking down.

I've been looking at Grodan (rockwool) mini cubes, Growstones, turface and other substances. Since 5-1-1 and gritty act as a quasi hydroponic medium, I figure there should be something out there that has the right water retaining characteristics. Most of the hydroponic mixes are made for recirculating or constant drip, not leaving trees outside and watering once every few days.

Anyone tried this?

Comments (87)

  • johns.coastal.patio
    9 years ago

    That makes more sense, Josh. The words "herds" and "boom and bust" are certainly an evocative description. Not sure how I translate that into actual risk though.

  • greenman28 NorCal 7b/8a
    9 years ago

    The micro-organisms rapidly reproduce and colonize the potting mix when temperature and moisture are favorable; however, in the heat of day, those populations are reduced due to heat and diminishing moisture. If one attempts to fertilize when the population is low (in a "bust"), the fertilizer won't be broken down into useable form for the plant....so growth potential is limited until the population of microbes increases to the point where the organic nutrients are broken down in a form and quantity the plant can use.

    The risk is to the wallet (inefficient use of fertilizer) and to growth potential. As always, if one is going to use organic methods, one should use larger containers or raised beds.

    Josh

  • Jay Part Shade (Zone 10B, S21, Los Angeles)
    Original Author
    9 years ago

    Hey Josh, great info on organics!

    Any thoughts on an inorganic 5-1-1 mix? Or what could replace bark? I'm thinking some combo of pumice, turface, DE and perlite should do it.

  • the_yard_guy
    9 years ago

    From a minimalistic point of view the "soil" can be just about any materiel you wish it to be, as long as it contains moisture, oxygen, and food in the correct amounts and it provides some form of support for the roots and plant. Many types of inert, inorganic material would work. Depending on what materials you select you may have to water more frequently and fertilize more often than you would in a typical 5-1-1 mix but its certainly doable if you wish. I believe Al mentioned somewhere on here that he sometimes grows plants in 100% Turface.

    The Missouri Gravel technique relies basically on just pea gravel and moisture/fertilizer I believe. No organic material at all as far as I know.

    TYG

  • Jay Part Shade (Zone 10B, S21, Los Angeles)
    Original Author
    9 years ago

    Hey Yard guy, totally agree, I'm trying to see if there's a way I can get close to the moisture retention of 5-1-1 but inorganically. Turface seems like it's a good replacement for peat. I'm thinking pumice, lava and/or DE is a good replacement for bark fines.

  • the_yard_guy
    9 years ago

    Jay,

    If I recall correctly, I think I read that Al mentioned that DE (NAPA Floor Dry, OptiSorb, etc.) can be used as a substitute for Turface. I think they are more or less interchangeable. I think granite and perlite are also fairly interchangeable. I've never used pumice or lava rock (not very easy to come by that stuff in Michigan lol) but I've also heard good things about them.

    This doesn't answer your question at all, but I think I also recall reading on here somewhere that fir bark lasts quite a bit longer in soil mixes than pine bark. Takes much longer to break down. Since you are on the West Coast you might find fir bark easier to come across then pine bark. That of course has nothing to do with inorganic, just mentioning that in case you are interested.

    TYG

  • Joe1980
    9 years ago

    If you grow in straight turface, you will have far more moisture retention than the 511 mix. I see no point in using both turface and DE in the same mix, as they are close to the same thing. I wouldn't really say turface is a replacement for peat, as they are totally different things. You could say that turface holds a good deal of water, grit holds just above none at all, and bark draws the line down the middle. That about sums up gritty mix. With that said, you can easily see how one could alter the moisture retention by adding or subtracting ingredients. You simply change the ratio of your moisture holding ingredients (turface, DE), and your non-moisture holding ingredients (grit, perlite).

    All in all, you may have to approach this from a different angle. Rather than trying to "find a replacement" for the 511 mix ingredients, just look at creating an inorganic mix that fulfills your needs. If you just settle on what you feel is a good replacement for the bark and peat, then mix them up at 511 ratios, you'll have a mix that doesn't even resemble the original 511 mix. I think you gotta knock down this mountain you've created, and bring it back to mole hill status. Focus on creating an inorganic gritty mix with some of the above mentioned ingredients in this thread, water and fertilize properly, and see how it goes. If you feel it's not holding enough moisture, or it's too wet, make adjustments. The answer will eventually come to you, but not overnight.

    Joe

  • johns.coastal.patio
    9 years ago

    I'm afraid Josh, that isn't really making sense to me. I do have a chemistry background, so maybe you can help me get there.

    The visuals of "micro herds" thundering in pots is strong, but I'm not sure it is really the way soil communities work.

    In particular, you are making the argument that one high organic matter system (5-1-1, 86% OM) will retain stable microenvironments through the day, while another high OM mix (say 50-80% compost) will go wild.

    Is that science, or is that visualization?

    (ha, spell check changed microenvironments to microcomputers. fixed.)

    This post was edited by johns.coastal.patio on Thu, Jun 5, 14 at 22:14

  • johns.coastal.patio
    9 years ago

    (I suspect that rapid, wild changes, are things that people say, rather than things that have been documented, in hard chemistry of the soil.)

    Update: I found Issues with compost in potting mix in a University of Vermont Extension document. "Boom and bust" is not one of them.

    Like anything it's not nirvana, but for people used to choosing just the right pine fines, other people looking for good compost should not be surprising.

    This post was edited by johns.coastal.patio on Thu, Jun 5, 14 at 22:37

  • greenman28 NorCal 7b/8a
    9 years ago

    Re: inorganic mixes, I think quite a few folks are using 2 parts non-porous grit and 1 part Turface. DE is a great sub for Turface...in fact, it has a slightly better CEC, and holds a little more moisture per weight. Perlite holds a LOT more moisture than granite, though, so don't use those interchangeably.

    John, I'm not really sure what you're asking here:
    "In particular, you are making the argument that one high organic matter system (5-1-1, 86% OM) will retain stable microenvironments through the day, while another high OM mix (say 50-80% compost) will go wild."

    What I'm saying is that using a synthetic fertilizer doesn't require micro-organism "herds" to cleave hydrocarbon chains and reduce organic nutrients to elemental form...because the synthetic is already in a form useable to the plant.

    5-1-1 is every bit as susceptible to overheating and drying out if used in smaller containers, and so the micro-organisms will be going through "boom and bust" cycles as they would in similar organic mixes of the same volume.

    Josh

  • johns.coastal.patio
    9 years ago

    It's just that you set up this great vsiual, Josh. It had herds thundering, spooked by lightening, heading for the metaphorical cliff ... maybe Bruce Dern in there somewhere.

    I've shown that the University of Vermont doesn't worry about that.

    So now you've moved to "need to cleave."

    New goalposts, and presumabley ones now where you think the "organic" mixture is never fed MiracleGro?

    For what it's worth, I use compost in my medium and MiracleGro (clone) too. In terms of "efficiency" for my small garden, my $4 on-sale purchase should last me 3-4 years.

    Someone probably could do it with a compost based mix and then organic fertilizers, but it is not my goal right now.

  • Jay Part Shade (Zone 10B, S21, Los Angeles)
    Original Author
    9 years ago

    Thanks Josh, that's helpful -- so it sounds like DE over turface. Does pumice fit in somewhere? I'd really like to stay away from grit, it's just too heavy for my 15 gal pots. Maybe a combination of pumice, DE and perlite?

    Also, is there an upper limit to water retention while still providing the necessary oxygen exchange? My dream mix would hold the water of a peat-based mix with the long term performance of gritty.

    Joe: you're right, I'll probably have to do some tests. But I'm already spending way too much time on this hobby, I guess that goes with the territory :)

    This post was edited by Jay-Part-Shade on Thu, Jun 5, 14 at 23:29

  • johns.coastal.patio
    9 years ago

    Sorry to derail as far as I have, Jay.

    I guess it's crazy to me that I can say something as open as this: The constellation of potting mixes is very large. At the other extreme from synthetic mixes, we have whole families of organic and permaculture styles.

    As I've said, I think the fact that all these styles are used by commercial growers means that they can and do work, and provide useful ROI.

    There are commercial growers of greenhouse crops using synthetic mixes, and people using compost as well.

    Whatever your interest, you can probably find a model that works.

    Then, after that, I have to defend things that work.

    Defending what works for me is not actually attacking what works for you.

  • Jay Part Shade (Zone 10B, S21, Los Angeles)
    Original Author
    9 years ago

    Hey John, I don't think anyone is disagreeing with you, I know I'm not. I love compost and full organics. My goal here is to find a mix for my trees that never breaks down. Whether or not it performs better with synthetic or organic fertilizers is a completely separate issue.

  • greenman28 NorCal 7b/8a
    9 years ago

    John, I haven't moved the goal-posts in the slightest, and it irks me honestly that you would throw that rhetoric at me. I've attempted to address two key elements of the organic conundrum and why many folks seek an inorganic mix. The first is the issue of drainage and aeration; the second is the issue of fertilization efficiency. Drainage and aeration has been covered satisfactorily already, so I posted on the particulars of organic and synthetic nutrient efficacy.

    I tried to be very specific for you regarding the two distinct issues that are tied to smaller volumes of mix, organic or otherwise.

    I'm certainly not telling you to change your methods; I'm merely suggesting that one can perhaps coax more from their gardening experience by anticipating the likely Limitations of an organic mix fed with organic fertilizers.

    Josh

  • johns.coastal.patio
    9 years ago

    Josh, you are making "the bumblebee can't fly arguments."

    And you think those arguments trump all the flying bumblebees in the world.

    I guess this is the way of the internet. There can be 1001 commercial growers out there with a compost based mix, but on a back thread in some forum some guy can argue that it is all impossible.

    (And you certainly discarded the whole "boom and bust" thing when I gave you the University of Vermont concerns, to name some more things that are not University of Vermont concerns.)

    I think it was pretty up-front of me to link to that, the actual concerns that actual growers acknowledge, and work around.

    UMassAmherst: Organic Growing Media and Fertilizers for Greenhouses

    That also does not speak of "boom or bust" or difficulties cleaving hydrocarbon chains.

    This post was edited by johns.coastal.patio on Fri, Jun 6, 14 at 1:04

  • greenman28 NorCal 7b/8a
    9 years ago

    Wrong, John, absolutely wrong.

    More of your insulting rhetoric...instead of goal-posts, you've saddled yourself a bumblebee this time.

    Where have I written that organic gardening is impossible? I've written of the inefficiency and the unpredictability (not the outright impossibility) of using organic fertilizers in smaller volumes of mix. And I've been writing the same thing for several years now. Take note of what I wrote most lately: "I'm merely suggesting that one can perhaps coax more from their gardening experience by anticipating the likely Limitations of an organic mix fed with organic fertilizers." That's a diplomatic way of saying that While one might be satisfied with their current level of success, a greater level of success might be achieved by working to reduce the Limitations of a particular method.

    I certainly did not discard the whole "boom and bust" thing. Where on earth did you misread that? I shall quote myself for you, where I repeated exactly what I wrote before: "What I'm saying is that using a synthetic fertilizer doesn't require micro-organism "herds" to cleave hydrocarbon chains and reduce organic nutrients to elemental form...because the synthetic is already in a form useable to the plant.

    5-1-1 is every bit as susceptible to overheating and drying out if used in smaller containers, and so the micro-organisms will be going through "boom and bust" cycles as they would in similar organic mixes of the same volume."

    Doesn't seem so hard to understand. Perhaps you are being intentionally obtuse in order to argue and insult those who thought you were interested in an actual discussion.

    Josh

  • JerryVentura Jordan
    9 years ago

    Ok, forget the organics and compost, that's another thread.
    Jay, have you ever considered that the bark isn't going to break down as much as you think it is in the time period that the plant is going to be in that container before it needs to be repotted? I just repotted a plumeria that was in a little pot for over three years and I don't think the bark broke down at all. The plant was just about root bound and the mix looked like I just put it together. I really think you'll be repotting before that bark gives you trouble, and how many years would it take before it came close to the texture of peat? I think a little fir bark is good for the critters.

  • drew51 SE MI Z5b/6a
    9 years ago

    "I've attempted to address two key elements of the organic conundrum and why many folks seek an inorganic mix. The first is the issue of drainage and aeration; the second is the issue of fertilization efficiency. Drainage and aeration has been covered satisfactorily already, so I posted on the particulars of organic and synthetic nutrient efficacy."

    This is what I was worried about when using organic mixes. But I have found adding compost is not really a problem as far as drainage and aeration. I found this to be kind of a myth really. Compost holds moisture like peat does, and to be technical peat is compost. So cut the peat add compost, as it is virtually the same thing. All these years you have been adding compost to your mixes. That is if you use peat. I also discovered that using DE over perlite increases aeration, but does add more water retention. Which I have found useful, as it tends to be like a moisture control sopping up excess water. Also because the pore size is larger than turface, water in DE is a lot more available to the plants, as noted in numerous studies. My pots are in the open, and it often rains a lot, DE I have found to be very useful.

    I'm not really interested in being organic. I'm interested in the best environment for my plants. So I agree about the fertilizer efficiency. I like to use organics as nutrition is always there, and there when the plants need it. But at times I need quick adjustments, so I use both chemical and organic fertilizers. I have found this approach to work extremely well.I'm in zone 6 and I'll be harvesting tomatoes from my 3-4 foot plants in about a week. Not a bad size for zone 6 at the start of June.

    I have stated as such a thousand times on this forum, but people see, and read what they want to and ignore the obvious. Not much I can do about that.

    As far as a good synthetic mix for trees, that interests me somewhat, but I want it for cacti which I don't transplant very often, hence the need for a long lasting mix.
    I have observed that bark breaking down before I transplant as not a problem as long as it is fast draining.
    The drainage slows, but not by enough to matter. One just has to be careful about watering. I don't leave my cacti in the open. An overhanging porch protects them from rainfall.
    I also use clay pots, and you can have just compost in clay and it will dry quickly, again ways to adjust for the water retention of compost, very easy to adjust for it. And I feel the benefits of a living media out way the few easily overcome disadvantages. The new cloth pots are very much like clay pots. This makes using compost that much easier.
    No doubt the trend is moving away from soilless mixes. It's a good thing it is taught here how to make them, as soon buying them will be difficult.

  • Joe1980
    9 years ago

    I'd like to just add that if commercial growers are to be brought into the discussion, it should be noted that commercial growers have one goal: profit. The long term health of what they grow is not their priority, making money is. That means they'll choose the most economical materials and methods possible, which means they aren't going to spend extra money on things like high quality pots or anything, and certainly not on potting mix material. Not to mention the labor it takes to sift such material, and the more frequent watering and fertilizing required.

    Joe

  • Jay Part Shade (Zone 10B, S21, Los Angeles)
    Original Author
    9 years ago

    JERRY: You're possibly right about bark not breaking down over 3+ years. My issue with bark has been more about the quality coming out of the bag (all over the place) and what I perceive as a bell curve of performance. It starts off not quite ideal, breaks down a little bit and works really well then breaks down too much. Out of my 50 or so plants, I can see some where the mix just isn't performing as well and I think that comes down to the massive different qualities of bark I've gotten.

    Also, this is more of a thought experiment -- if 5-1-1 and gritty are designed to prevent compaction and not break down like peat-based mixes, why not go all the way? Is there something that inherently doesn't work in an all inorganic mix for long term plant growth? I just don't know.

    DREW: Not to get back to the organics argument, but it's worth noting that I've found single crop plants like tomatoes are fine for peat, compost, etc. and perform better than 5-1-1 in my experience. I've got cucumbers and some tomatoes in peat and compost right now and they're doing great. But from previous years I know the mix will only last 6 months at most before it becomes a near solid block of concrete. This year, I'll try to keep my veggies in the 5-1-1 going through the winter (this being LA and all).

    My goals are growing rare fruit trees long term in big pots and slow growing succulents and cacti. I'm not really worried about my veggies, seeds are cheap and tomatoes are practically a weed :)

    JOE: You bring up an interesting point and I do wonder about commercial growers. Out of the few dozen trees I've purchased, about half come in a bark-based mix and the other come in a massively heavy granite mix. That said, those growers are growing to a certain point before selling them (usually after 2 years), and not really concerned about making sure the mix stays stable beyond that. I'm not sure there's any commercial tree growers that are growing for long term fruit production rather than selling the trees. If there are, I'd be really curious to know what they do.

  • JerryVentura Jordan
    9 years ago

    Jay I don't have the problem with bark that you seem to find, it's probably because I buy E.B. Stone Orchid Bark, it's fir and it's really a nice bark, it holds up for the long haul. I do a gritty version and I leave my plants go for a while before repotting, so that's why my choice of bark was important.

    Jerry

  • johns.coastal.patio
    9 years ago

    Josh, do you have anything more than metaphor?

    Seriously, you tell these stories, and I return with university extension papers, and you tell more stories. I'd like to just add that if commercial growers are to be brought into the discussion, it should be noted that commercial growers have one goal: profit. The long term health of what they grow is not their priority, making money is.

    That sir, is a classic example of confirmation bias in action.

    Think of a reason to wave away actual results with positive ROI, even by suggesting that ROI is a bad thing.

    I spent $0 out of pocket for my potting soil (for tomatoes) this year, and my tomatoes are 6-7 feet tall.

    I call that ROI, and not a bad thing.

    This post was edited by johns.coastal.patio on Fri, Jun 6, 14 at 11:31

  • johns.coastal.patio
    9 years ago

    Josh, seriously, if you want to say this to a scientist:
    "I've written of the inefficiency and the unpredictability (not the outright impossibility) of using organic fertilizers in smaller volumes of mix."

    You need a study. Not a story.

    And, if there really is "inefficiency and the unpredictability" it will show up as poor ROI for organic growers, small and large.

  • nil13
    9 years ago

    I feel the need to add that most wholesale growers use a lot of CRF and fertigation. The media they use is generally built around partially composted bark. This is because partially composted bark has better water retention than fresh bark. Fresh bark lasts longer, but since they repot every season that is not a concern.

  • johns.coastal.patio
    9 years ago

    Here is the University of Connecticut on fertilizing houseplants:
    The fertilizer label will also state from what sources these nutrients are derived; chemical and/or organic. If synthetic or chemical fertilizers contain trace elements, these too will be listed on the label. Trace elements or micronutrients are needed by plants in very small amounts and include iron, boron, zinc, copper, molybdenum, chlorine and manganese. It is usually safe to assume that organically derived fertilizers, because of their nature, contain some or all of the necessary micronutrients. Potting mixes that have a mineral soil component may also supply sufficient amounts of micronutrients. If you are not using an organic houseplant fertilizer, consider purchasing a chemical fertilizer that does include micronutrients since they are typically not present in soilless potting mixes.

    See if you can find a word on your worries in that paper, Josh.

  • nil13
    9 years ago

    Jay, your dream about a completely inorganic medium with thesame properties as peat based media is completely quixotic. Give it up and just deal with watering frequency by installing an irrigation system.

  • Jay Part Shade (Zone 10B, S21, Los Angeles)
    Original Author
    9 years ago

    John: all interesting info, but can we keep this thread on topic? Your points regarding organic fertilizers and mixes would probably be best suited for a new thread :)

  • johns.coastal.patio
    9 years ago

    I know nil13, and I think those methods are a good model for space-intensive gardening. They come in more conventional and organic certified variations.

    Which we choose can be based on our general preferences, but also our local costs.

  • johns.coastal.patio
    9 years ago

    Ok Jay.

    I tried to just hold the line at "all these things work," but again that took some "defense."

    Here it is: Big Tent Container Gardening

    This post was edited by johns.coastal.patio on Fri, Jun 6, 14 at 12:22

  • Joe1980
    9 years ago

    John, I can see you like to argue with people on the internet, and like to put words into people's mouths or make assumptions about views and intent. You assume I am complaining about commercial growers and their ROI, and that I think ROI/profit is a bad thing. You are dead wrong. I merely stated that commercial growers' number one goal is profit, and there is no argument you can make against that. Do they want to provide other things like quality products too? Sure. But, profit still trumps that. But, you've now transformed this thread into a heated argument with personal attacks, so its time for me to move on.

    Jay, I hope you find what you're looking for, and good luck in your growing.

    Joe

  • drew51 SE MI Z5b/6a
    9 years ago

    "Do they want to provide other things like quality products too? Sure. But, profit still trumps that. "

    I disagree, without quality, one will be without profit.
    At least in the long run. Such bad business practices will result in failure eventually.
    Like GM trying to save money by not recalling a part,. Did that work? Did they save money?

  • johns.coastal.patio
    9 years ago

    The important thing to understand, Joe, is that I am defending everyone's right to find their own path.

    People come back with reasons to disdain one or another successful method.

    If you really want to do that, bring it to the new thread.

  • greenman28 NorCal 7b/8a
    9 years ago

    Using uncomposted bark, I find that bark-based mixes can go approximately 3 years, and then the breakdown becomes quite obvious (and has a definite effect on drainage and aeration). I've documented some slightly different bark-based mixes after 2 - 3 years.

    In this first mix, wherein I grew my Avocado for 2 years, the breakdown was less noticeable due to the significant inclusion of various grit - perlite, pumice, scoria, turface, and some quartzite.

    Josh

  • greenman28 NorCal 7b/8a
    9 years ago

    In this second mix - bark, perlite, and scoria (red lava rock) - the breakdown was much more apparent in the same 2 year time-frame. This mix is what I used for my Giant Chainfern (outdoors in a large container year-round). I fertilized with Fish Emulsion solely, watered much more often (due to the plant being a fern), and the container received Winter rain. Notice also that the mix was colonized by moss due to the favorable conditions created by the fern. These factors together contribute to the decomposition of the bark in the mix.

    Josh

  • Jay Part Shade (Zone 10B, S21, Los Angeles)
    Original Author
    9 years ago

    Thanks Josh, that's really helpful!

    If you were to try mixing an inorganic mix (without grit, too heavy for me), what would you try? Would some combination of pumice, DE and perlite work? When potting up, it'd be great not to have to shake out the mix from the roots. Unless I'm missing something, is there any real reason why there has to be an organic component in the mix?

  • greenman28 NorCal 7b/8a
    9 years ago

    Thanks, Jay.
    The bark just happens to be an excellent filler (durable, economical, fairly light-weight, favorable pH, favorable moisture retention curve).

    Your question about creating an inorganic mix is a bit more difficult due to the moisture retention of each of those three ingredients. The function of the non-porous grit (granite, quartzite) is to adjust down the moisture, which is very helpful...but also quite heavy.

    I have some succulents (Jades) in pure Turface, and some in pure scoria (red and grey lava rock), but I'm not sure how well that would translate to larger containers and different plant species.

    If you have access to large coarse Perlite, you might be able to displace enough moisture to make a mix of pumice and Perlite work.

    Josh

  • nil13
    9 years ago

    Josh, I bet if you dug down to the bottom of those containers it would look even more decomposed.

    I should have taken pics of some of the grasses I just split up that were in 1s. The pots were only 1/4 full and the media that was left looked exactly like worm castings.

    Jay, are you thinking about adding perlite for weight? Also, if you do use perlite don't get the thermorock crap they have most places, too mny fines. You need the sifted large horticultural grade stuff.

  • nil13
    9 years ago

    Jay, if your problem with bark is consistency, just start buying orchiata or the cheaper good stuff the orchid folks use. You miht want to check out Yamada Co. Down in Gardena.

  • greenman28 NorCal 7b/8a
    9 years ago

    Indeed, Nil, the lower layers are much more evenly broken down. Thankfully, the mix doesn't compact much and so the potting mix *level* doesn't sink as much as other mixes do.

    Josh

  • Jay Part Shade (Zone 10B, S21, Los Angeles)
    Original Author
    9 years ago

    Josh, great info, it sounds like I'll probably need to experiment to get the right ratios. I'm not worried about replacing the grit, more like finding something (or a mix of something) that comes close to mimicking the bark in 5-1-1. And I'm growing in 15 gal bags, all fruit trees, mostly sub tropicals, so it seems like I should try to find something that fits their needs. My biggest concern are my avocados, I have six now, a couple rare ones, and I really want to keep those guys happy.

    Nil, you're right, I've gone through tons of bags of the cheap crap and it's like I'm inhaling fines. The hydro store in Atwater (Atwater Hydro) has both the medium and huge size perlite for a reasonable price (I think $15-20 for a 3cuft bag). I've found Greenall Microbark from Armstrong on San Fernando is really excellent quality, but it's $10/bag to Home Depot's $4 so it pains me to spend that much filling up the truck since everything at Armstrong is so damn overpriced. I mean, $50 for a 5 gal mission fig? They're out of their minds.

  • greenman28 NorCal 7b/8a
    9 years ago

    Ah, the Avocado....touchy plants in containers up here. I hate doing any root-work on mine, which is why I've kept it in the same mix for several years now. The last mix change that I did, I used a mix of screened fir bark (Greenall), red lava rock, and turface. I flood the mix these days and use a drip-tray because the poor tree is so root-bound and wilts if not watered every other day or so.

    Josh

  • greenman28 NorCal 7b/8a
    9 years ago

    Here's a shot of the Avocado mix....
    Fir bark, scoria, turface.

    Josh

  • nil13
    9 years ago

    Well Yamada has 4 cuft bags of perlite for about $10, and 2 cuft bags of orchid seedling bark for $9. The best part is they have 50# bags of Nutricote 180 for about $70.

    This post was edited by nil13 on Sat, Jun 7, 14 at 12:40

  • Ernie
    9 years ago

    One thing that I wonder, Jay, is if the wicking properties of the fabric pots will offset, at least to some extent, the compaction/breakdown of your potting media over time. Yes, the organic components (bark, peat, etc.) will break down into ever smaller particles, but, since fabric pots are less likely to support a perched water table when in direct contact with soil, does that really matter? With that question in mind, I've begun using a modified 5-1-1 recipe for all of my plants in fabric pots (degradable Root Pouches) that's five parts aged bark fines, 2 parts fine material (peat, compost, etc.), and 1/2 part each coarse perlite and D.E. My hope is that this mix will do a better job of retaining moisture while the fabric pots will help to maintain sufficient aeration for healthy root growth. I'm planning to leave the plants in these pots for at least 2-3 years before changing out the mix, so perhaps we can compare notes in a couple of years.

  • Jay Part Shade (Zone 10B, S21, Los Angeles)
    Original Author
    9 years ago

    JOSH: Good to know about the avocado, I'm betting that it actually loves being flooded that often, given how they love drainage and they're grown commercially on hills. I didn't bare root my first avocado (a sir prize). It was in a decomposed granite mix that drained really well, so I just knocked a bunch of dirt off and stuck it in. It's been growing pretty well, but I'm worried I might want to bare root it to a more consistent mix. My Jan Boyce was bare rooted and nearly died, lost all but one sad leaf and half its branch tips turned black. But now it's flushing out all new growth. The Mexicola and Lamb Hass laughed at being bare rooted and acted like nothing happened, Mexicola especially, the thing is indestructible, and the lamb hass kept holding fruit (that I've since removed). I also have a Hass and Kona Sarwil that complained a little but were otherwise fine with bare rooting. And all this was right before the crazy heat wave and fire storm down here.

    NIL: WOW, fantastic resource. I didn't know about Nutricote before but their product line is impressive -- I need to make a field trip to Yamada. It's the one in Gardena, right?

    SHAZAAM: Interesting ideas, the bags are definitely big on wicking and air exchange. None of my bags are touching the earth, they're all on my patio, driveway or elsewhere. I imagine if I put them on bare dirt, they'd act like a raised bed and one could get away with almost any mix. In fact, if I were doing that, I'd do a raised bed mix to encourage more worms and things to till the bed (I did that last year with a peat-mix in 10 and 15 gal bags and it worked great, tons of worms and growth). I just calculated how many gallons of 5-1-1 I've made. It's around 350 -- 20 15-gal bags and the rest 7 and 3 gal. I wanted to stick the basic recipe before going off the reservation, but, yes, let's compare notes. The more I read about DE, the more I think it's a great addition.

  • nil13
    9 years ago

    Yeah it's in Gardena.

    If you find a good source for big DE in LA let us know. You should know though that you can get Turface just down the street at Ewing on Colorado.

  • greenman28 NorCal 7b/8a
    9 years ago

    Jay, each time I re-potted my Avocado, it lost all the older leaves, keeping only a few top leaves. Then I finally got smart....and I put the thing in deep shade after re-potting, and I watered the new mix every day to keep the *upper* inches moist. That really cut down on the leaf loss. Now it's a monster, and still in that tiny clay pot. It's developed a lean, though, so I'll have to prune it pretty hard.

    Josh

  • Jay Part Shade (Zone 10B, S21, Los Angeles)
    Original Author
    9 years ago

    NIL: Good to know about the Turface and I've been looking for a source of Axis without success, their website makes finding it near impossible. I'm thinking I'll start with Optidry from Oreilly just to experiment before filling up the truck.

    JOSH: Nice looking avocado -- those are probably the biggest leaves I've ever seen! Grown from seed, I assume? What was the donor fruit (Hass?)? Are you planning on growing it to fruit? Or grafting? Or just decorative?

    Yeah, I stuck all my trees inside after repotting them during the heatwave and usually keep everything else in shade for at least a couple of weeks. The handles on the bags and a small dolly make it easy to move. Also, I do the bark mulch on top since avocados have a lot of surface roots. But I don't think you have any weak root issues :)

  • greenman28 NorCal 7b/8a
    9 years ago

    Hehe :-)
    I'm growing this one decoratively...it's about 4.5 year's old from seed. I can't remember what the donor fruit was (probably a Hass as they're popular up here). The seedling popped up in my garden, so I dug it up in November and have been Wintering it indoors ever since. I prune it a couple times per season in an attempt to keep it compact, bushy, and with multiple branches to its canopy. It really loves sun, water, and fertilizer....but you know all that!

    Josh