Is bagged lava-rock 'mulch' ever treated / impure? (like wood mulch often is?)

SU2

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I've only been in this hobby a year so my substrate mix has been ever-changing, I've been moving away from diatomaceous earth granules to perlite as my main ingredient, and have always been using ~15% other stuff (<5% tan sphagnum, ~10% lava rock + bark-chips) to change the properties a bit, anyways I recently read about how impure many of the wood-chip mulches are (stuff like construction lumber (pressure treated) that's further treated before getting bagged, and I don't just mean the dyed-color types!), so I've stopped using wood chips of any sort and am now using only lava rock, am hoping to find if there's any concern about the quality/purity of the lava rock you'd get when buying it by the bag (the stuff I get doesn't say 'mulch' it's just a ~30lbs sack that says 'red lava rock', I smash them and screen/sieve them, then rinse and use the multiple grades/sizes for various things from big ones at the bottoms of my containers, medium ones as top-dressing/mulch, and smallest ones in the substrate mix itself)

Am actually hoping to switch to spherical hydroponic media soon, still just learning about it though, and have been using lava rock more and more the past month so want to be sure it's not known for some problem I'm unaware of! Thanks :)
 

M. Frary

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My lava is already the perfect size. No Leavenworth activities needed.
I just use that and the diatomaceous earth from Napa.
I am going to get my hands on Optisorb because it is larger in size.
I do add pine bark when I have it and feel like it but the lava and D.E. are the main ingredients.
I would never use wood chips or commercial landscape mulch. You never know what gets tossed into the chipper/shredder. Some trees wood even prohibits the growth of other trees. Like walnut.
 

cbroad

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@SU2
I don't know much about lava but I have a ficus I'm growing hydroponically and I use Hydroton (LECA: lightweight expanded clay aggregate), but I think they are too large and will have too large of a pore space because of its round shape. It works for hydroponics because it's constantly being watered but I think it will dry too fast for bonsai culture. I have seen a "popcorn" type of Hydroton that is smaller and irregular in shape that will probably work pretty well for bonsai.

Good luck!
 

RKatzin

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Decomposed wood, like this old growth Douglas fir stump or the chunk of pencil cedar, you can crush a piece in your hand with your thumb. Crush it and sift to size. Mix with equal part of forest humus and sphagnum moss. This is raked up from the floor of the forest, under the oaks and Madrone. Cut this mixture with equal amount of pumice for a 50/50 for most deciduous trees and adjust the mix for all things considered.
Due to changes in logging practice these finds are becoming a thing of the past. Now trees are cut close to the ground and what can't be milled gets chipped. While they last it's free dirt, out there in the woods. My place is littered with them and I'm sure if you look around you'll find the same kind of stuff in your neck of the woods. If not I can box some up and boot it out to you.IMG_20170813_134251829.jpg IMG_20170813_134141473.jpg IMG_20170813_134526231.jpg
 

SU2

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My lava is already the perfect size. No Leavenworth activities needed.
I just use that and the diatomaceous earth from Napa.
I am going to get my hands on Optisorb because it is larger in size.
I do add pine bark when I have it and feel like it but the lava and D.E. are the main ingredients.
I would never use wood chips or commercial landscape mulch. You never know what gets tossed into the chipper/shredder. Some trees wood even prohibits the growth of other trees. Like walnut.
Yeah I loved them for a while as they're a good, reliable way to have 'water reservoirs' in an otherwise quick-to-dry mix, it's good for humidity in the root-zone in an area like mine where they dry quickly...but the concerns between bad product, additives, and - as you mentioned - competing hormones/chemicals from other plants, I've begun collecting wood/bark chips every time I see them, have a little bucket building-up with them - will put them to use on something I care less about than my bonsai!
 

SU2

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@SU2
I don't know much about lava but I have a ficus I'm growing hydroponically and I use Hydroton (LECA: lightweight expanded clay aggregate), but I think they are too large and will have too large of a pore space because of its round shape. It works for hydroponics because it's constantly being watered but I think it will dry too fast for bonsai culture. I have seen a "popcorn" type of Hydroton that is smaller and irregular in shape that will probably work pretty well for bonsai.

Good luck!

Are you able to explain the various types of clays(or other materials?) in these hydroponic spherical substrates? I'm just utterly confused at the 'varieties', whether they even matter... Re too-large, that can be a problem for sure, but large pore space isn't a problem as I'd just add a higher % sphagnum moss to the mix to keep it humid in there (and I do twice daily minimum visits to my garden, so get away with quick-drying media but would adjust if it were too-quick drying)

Re the 'popcorn type', I'd sooner stay with perlite - the 'ball bearing principle' of the spheres is the biggest factor in my desire to change-over to them!
 

cbroad

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@SU2
Not sure exactly what kind of clay is used, but it is high fired so it won't break down, is very porous, and I'm assuming being clay it will have a high CEC.

Adding too much organic matter could be a problem because the soil will eventually break down and fill these pore spaces and potentially clog them. Something I read said use about 30% total volume of Hydroton. I would still try to use coarse media with Hydroton, like orchid bark or unmilled peat moss for water retention, anything that will break down the slowest and not settle near the bottom of the pot as fast as a fine grade soil.

When I bought my bag of Hydroton, there was varying grades of clay balls and I'm pretty sure you can find bags with just the smaller size balls; some of the balls in my bag were about the circumference of a nickel, I bet something dime size would be better (still decent sized pore spaces but not overly large).
 

SU2

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I'd think lava is pretty inert seeing that it's blown out of a volcano at 1300 °F to 2400 °F.
I was asking about bagged stuff, I know that it's pure when fresh (just like wood is), was wondering if it ever gets processed in any way (like some wood does)
 

Shima

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I can't imagine what could be done to it.
 

Josh86

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A quick rinse would wash anything away from lava rock as it doesn't soak up anything like wood would
 
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Anthony

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@SU2,

try this 5 mm silica based gravel and some sifted compost at
1 spade compost to 2 spades of gravel.

Try it on seedlings in small 7 oz styro cups and see how you do.

To make more moist add a little more compost, drier more gravel.
Test and see how your water and atmosphere handles it.

Perlite tends to smash easily, you could use red lava for water retention in inorganics.

As I mentioned before Leca can be had at 3 mm [ the hydroponic pebbles ]
thus far the test subject is doing very well in our handmade version.
Good Day
Anthony
 
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SU2

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A quick rinse would wash anything away from lava rock as it doesn't soak up anything like wood would
Good call! I don't do any quick-rinse either, I know this'll sound pretty OCD but I split a bag of lava rock, divide it into 3 grades/sizes and store it that way, when I go to use it I rinse it until it can sit in water w/o letting off anything! I do that with all my substrates, wash the living hell out of them and sieve them to ensure no fine particles!
 

SU2

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@SU2,

try this 5 mm silica based gravel and some sifted compost at
1 spade compost to 2 spades of gravel.

Try it on seedlings in small 7 oz styro cups and see how you do.

To make more moist add a little more compost, drier more gravel.
Test and see how your water and atmosphere handles it.

Perlite tends to smash easily, you could use red lava for water retention in inorganics.

As I mentioned before Leca can be had at 3 mm [ the hydroponic pebbles ]
thus far the test subject is doing very well in our handmade version.
Good Day
Anthony

What type of place would you go for silica based gravel? I'd gotten a bag of pure portland cement (have started making bonsai pots :D ) and was planning to just use regular sand to make it mortar, after a couple experimental containers I'm fearing that my local 'sugar sand' here isn't 'sharp' enough for it so I need to find a place that 'deals in sand & stone' and home depot is the only spot I can think of....is there a stone/masonry equivalent of a lumberyard?

Re perlite smashing easily, this does bother me but the way I figure it is it only does that when perturbed, like it does not just break-down over time it only breaks when it's roughed-up, so I'm very cautious to be gentle with the stuff after I've sieved&washed/rinsed it, and even as I'm setting-up a tree in it I'm using really gentle pressure with my sticks to get it around the roots and really rely on 'watering-in' the substrate around the roots (it always drives me nuts seeing how aggressive people get with their chopsticks when setting-soil, feeder roots are very fragile! I probably use 5-10gal to water-in a typical tree when re-boxing!!) Once it's done and setup, that perlite shouldn't break down for ages unless it's messed with!

I'm certainly still interested in swapping-over to spherical leca/hydro substrates but the Irma storm really set me back in a lot of things so haven't even gotten around to finding/visiting the nearest hydroponics shop yet, have told myself I won't buy anymore perlite/lava rock though and next substrate purchase *must* be spherical!
 

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The only thing I ever found in a bag of lava was a big hunk of molten metal. Well is wasn't molten when I got it out of the bag, but it was a hunk of volcanic silver colored metal. I chucked it in my "garbage disposal" (a Rose of Sharon hedge privacy screen where I dump my shakins)
Don't know if it was silver, lead, uranium or what, but I can probably rule out uranium because the hedge doesn't glow at night and I haven't seen any 8 legged salamanders. I'll have to see if I can find and identify it this winter.

How do you smash your lava? I have 1/2 bag, and a small bag of geolite (fired clay) that has a very attractive dark grey to black color. I also would like to get some black lava as well.
 
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Anthony

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If you have access to a kiln --------------- just buy some earthenware clay say a 1lb
make a few long snakes at roughly 4 mm in width.
Cut up at 4 mm hand roll ,and send the balls to fire after drying.

Remember this is just a test, and the idea is to see how it works, not a torture
event, so no 5 lb or 20 lb etc events.

Ask at any place that does sand blasting or supplies for concrete mixing.
Just ask for the source and about stability to roots/water.

Roots also smash perlite as they grow and fill the container.
Good Day
Anthony
 
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SU2

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If you have access to a kiln --------------- just buy some earthenware clay say a 1lb
make a few long snakes at roughly 4 mm in width.
Cut up at 4 mm hand roll ,and send the balls to fire after drying.

Remember this is just a test, and the idea is to see how it works, not a torture
event, so no 5 lb or 20 lb etc events.

Ask at any place that does sand blasting or supplies for concrete mixing.
Just ask for the source and about stability to roots/water.

Roots also smash perlite as they grow and fill the container.
Good Day
Anthony
Great stuff, thanks! Unfortunately I've never even known of someone who had a kiln (excepting my arts&crafts class in highschool almost 2 decades ago!), although I can't help but wonder if it's not the type of thing you could DIY pretty simply with bricks (it's basically just an oven, right?) I'm all about DIY projects, would certainly get into this if I thought I could get my own kiln going however the substrate would be a distant second to being able to make bonsai pots with it!!!! I make wooden boxes now (or use colanders) but have recently started making containers out of cement, have two curing right now so we'll see how that goes :D

And re roots smashing the perlite, I can see that to *some* degree, I guess it depends how settled / tight it all is, but luckily in my case (a nursery of almost-all bougainvilleas) re-potting with regularity is OK, even advisable :)

Thanks again for the info, both here and my other threads!!
 

SU2

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The only thing I ever found in a bag of lava was a big hunk of molten metal. Well is wasn't molten when I got it out of the bag, but it was a hunk of volcanic silver colored metal. I chucked it in my "garbage disposal" (a Rose of Sharon hedge privacy screen where I dump my shakins)
Don't know if it was silver, lead, uranium or what, but I can probably rule out uranium because the hedge doesn't glow at night and I haven't seen any 8 legged salamanders. I'll have to see if I can find and identify it this winter.

How do you smash your lava? I have 1/2 bag, and a small bag of geolite (fired clay) that has a very attractive dark grey to black color. I also would like to get some black lava as well.

That hibiscus hedge sounds like the type of setup where I'd be thinking "god I could make something out of those trunks"!!!

Re smashing it, I've largely stopped that (did I mention doing so in this thread? I've been doing it less and less) but what I'd do is just go out to my driveway, lay down my cloth 'substrate cloth' (it's a black apron that I use exclusively with soil, like putting it over soil when carving a tree, or using it to hold used substrate flat in the sun to sun-sterilize it / dry it out), and on that cloth I pour the bag out and smash-up the bigger pieces. Whether I use a hammer or not it always ends with me rolling-up the apron, carrying it to the backyard and opening-up on a table, where I then quickly chuck all the pieces into one of three buckets (sml/md/lrg pieces), then it gets put with my bags of perlite, tan sphagnum and DE (diatomaceous earth, I get the granules from NAPA and am very happy with them!) and is ready-to-use whenever I need any, have found it's incredibly useful to have substrates and boxes 'ready to go' like this (they're not fully ready, I have strainers I use to clean the hell out of any substrates, I use the hose to rinse them in their strainer until the water runs clear) Between perlite, lava, DE and sphagnum (listed from least-->most water-holding ability), I've got everything I need! I use the largest lava as either bottom-dressing in larger boxes or as mulch on others, the smallest ones sometimes become part of a substrate, and the remaining small/mediums are used as bottom-dressings or mulches for smaller containers :) Lava rock is an exceptional mulch for me, particularly when using perlite-only substrates, as the lava rock shows when it's just a little moist so you can gauge wetness real easy if there's no DE or sphagnum in the mix to give a clue!
 

Mellow Mullet

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@SU2,

try this 5 mm silica based gravel and some sifted compost at
1 spade compost to 2 spades of gravel.

Try it on seedlings in small 7 oz styro cups and see how you do.

To make more moist add a little more compost, drier more gravel.
Test and see how your water and atmosphere handles it.

Perlite tends to smash easily, you could use red lava for water retention in inorganics.

As I mentioned before Leca can be had at 3 mm [ the hydroponic pebbles ]
thus far the test subject is doing very well in our handmade version.
Good Day
Anthony

WTF?

Lava is lava, they mine it and crush it, then sift it. After that they bag it and sell it. Nothing else is done to it to enhance it. You don't need a kiln, compost, or 5mm anything. Geeze.
 

Anthony

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Mellow,

please don't have a cow.

The idea here was before SU2's curious nature dies, to expose him to the Ball Bearing principle.
Red lava is not round.
Good Day
Anthony
 
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