Boiling bark

[sfhellwig]

I want to share what I have found about soil mixes and making your own but that is not what this thread is about. To stay on topic I imagine boiling the bark would be the worst thing for it. I understand where you're going but it would likely sterilize and actually set back the composting process. Someone else said that all organic material is composting to some degree. I know that when I knock out a dead tree or re-pot something what comes out sure looks more like dirt than the bark mix I put in. I guess that is the reason for the trend toward purely inorganic, the stability for 2-3 years between re-potting. I buy mine straight off the shelf, sift multiple times and use it. Not that I have lots of experience making me a trusted source but I have been doing this mixing for a few years and it performs as well or better than what I can get off the shelf.

As for getting the right stuff in the first place. It does sound like the one fellow had "nuggets". Someone mentioned the conditioner which sounds like the "Scotsmsn's Choice Organic Compost" that I add to my other bark. It looks like large chain saw chunks and is nice minus the fines. I used to get chipped bark from the local nursery but they always get it in too late and pull it early at the end of the season for personal use. The two times a year I want to buy it. So I found that I can use the pine bark mulch from, uh oh, Home Depot and Wal-Mart. We just have to be smart about what we buy there. Mine is a company called "Green Country" and comes from Springfield, MO so I guess that's almost local. I run it through 1/2" screen and use the big stuff to mulch pathways. Whats left can go straight for "nursery mix" or i can run it through a 1/4" screen and window screen to get a fairly small and consistent product for mixing for bonsai soil.

From there I mix it and use it. When I get it back it looks more like dirt. So I think anymore composting and you might be cutting yourself short on the usefullness of your product.

 

[Woody]

Just found this thread regarding using uncomposted pine bark.

There are three main problems I can see with regards to boiling the bark.

1. Boiling would kill any bacteria and fungi (including mycorrhizae). Ordinarily this wouldn't be a problem except that it could be of issue if you're trying to encourage an active microbial environment. Not that it would stay
sterile for long as the bugs will get back in there eventually. It's just that encouraging mycorrhizae is important for pines particularly but there is certainly evidence that other species also benefit from mycorrhizae populations
(eg junipers and even maples - it's just that their filaments aren't visible). Mind you mycorrhizae are more useful in colder climates where it's harder for plants to assimilate nutrients. In warmer climates, their presence is not
always necessary and it can even be hard to get them to grow in my experience.

2. The issue of nitrogen drawdown described by other posters. Because we fertilise our bonsai generously,
nitrogen drawdown is not such an issue. However for those that prefer to use organic fertilisers, note that any decrease in your microbial population will affect the performance of your organic fertilisers. This is especially the case for colder climates where the breakdown process will already be slowed down. Thus not such an issue if you use chemical ferts.

3. Potential for phytotoxins in bark. Another reason why pine bark needs composting is the breakdown of
phytotoxins which can slow growth down in other plants. This mechanism is recognised also where plants are planted in the presence of old roots from other plants. It's part of the way plants reduce compeition from other plants for resources etc. Boiling however is another way for these phytotoxins to be destroyed. The downside
though is that boiling invokes the two other problems addressed above.

Anyway that is what the science suggests. Actual experience stated by others may suggest otherwise but it's something to think about

 

[treebeard55]

Thanks for the input, Woody. I wasn't aware of the phytotoxin issue. Definitely something to think about!

Yes, boiling water gets hotter than a working compost pile. Composting may not kill mycorrizhae -- I simply don't know.

I think I'm going to go ahead with boiling a few quarts of bark, just for an experiment. If I learn anything of interest, I'll pass it along.

I'm also going to take a batch of fresh hardwood mulch, wet it thoroughly, bag it in black plastic, and put it where it will get as much sun as possible for a few months. That's as close as I can get to regular solarization: we have a small yard, and my lovely wife wouldn't be happy with a standard solarizing setup (such as John Kirby suggested) in public view.

 

[garywood]

Steve, throw a cup of household ammonia in the bag. It will take care of the nitrogen issues.
Wood

 

[Jessf]

Would baking your pine bark instead of boiling be of any use?

Any why do we need to compost the bark before use? I was of the impression that you can buy it from the store and use it right away.

 

[treebeard55]

Jess, baking would dry it out, which is something I don't want.

When anything organic is used fresh, fungi and microbes go to work on it breaking it down. They use up some nitrogen in the process, nitrogen you meant for the tree. You have to compensate for that. Also, as I just learned from Woody's post, pine bark and likely some others contain phytotoxins which are growth inhibitors; those need to be broken down, or they'll give your tree some grief, apparently.

The breakdown fungi, to my knowledge, don't attack the living tissues, but they can sure be noticeable! Here's a picture of the root system of a Ficus salicaria which I had potted in a mix with fairly fresh bark. All the white on the roots is fungi!

 

[Jessf]

So, composting helps to get rid of these harmful things like phytotoxins. Which leads us to your boiling question. If phytotoxins are present in the bark, and adding heat kills them, why doesn't baking work? yes, it dries it out but isn't rehydrating it after the fact an option? Once the bark is in the pot, will the good bacteria form, or is that something that only occurs in a compost heap?

I'm confused as to why we can't sterilize the bark with dry heat.

 

[rockm]

You can use wet, dry or moderately moist heat, whatever...Brent Walston says you can sterilize bark in a plastic turkey cooking bag in the oven if you put a wet towel in with it to prevent it bursting into flames

What you don't have to do is sterilize bark. There isn't really a reason to. From what I've heard over the yearsDecomposing bark in bonsai soil is of very little consequence. I think Brent posted a while back on the subject. Decomposing bark uses very little N in bonsai soil and the fertilization programs that bonsai incorporates more than makes up for anything lost to that process.

Additionally, cooking bark, like cooking anything else, hastens is structural breakdown. I would think that it would contribute to earlier soil collapse -- which would seem to be to be a bigger problem than phantom N usage...

 

[Dav4]

Thanks for the input, Woody. I wasn't aware of the phytotoxin issue. Definitely something to think about!

Yes, boiling water gets hotter than a working compost pile. Composting may not kill mycorrizhae -- I simply don't know.

I think I'm going to go ahead with boiling a few quarts of bark, just for an experiment. If I learn anything of interest, I'll pass it along.

I'm also going to take a batch of fresh hardwood mulch, wet it thoroughly, bag it in black plastic, and put it where it will get as much sun as possible for a few months. That's as close as I can get to regular solarization: we have a small yard, and my lovely wife wouldn't be happy with a standard solarizing setup (such as John Kirby suggested) in public view.

If you build a big enough pile of compostables, the middle of the pile can heat up to well over 120F. Sustained temps here for several days will kill off most beneficial bacteria and fungi...not a big deal, really, as they will quickly re-establish themselves once the pile cools.

For the record, I've used pine bark mulch, sifted, right out of the bag with no ill effects in all sorts of container plantings, including bonsai, with no ill effects. Honestly, I'd either do the black bag thing mentioned above, or just empty a few bags of pine bark mulch in a corner of the yard, wet it down, and forget it until next year. The KISS rule applies here, I think.

 

[treebeard55]

I'm not really interested in sterilizing the bark; that would be futile anyway, I think, given that it would be quickly recolonized by this and that. As several have mentioned.

My thought is more to jump-start the whole process that goes on in composting. Composting does involve some breakdown, yes, breakdown that continues in the pot and eventually makes it necessary to replace the soil. Would boiling break it down too far, haste soil collapse noticeably? I really don't know.

The more I think about it, the more I suspect that the presence of phytotoxins is the thing one would need to be significantly concerned about in using fresh bark. I haven't had a chance to research those much yet -- anyone else?

Thanks for the suggestion about the ammonia, Gary.

 

[rockm]

If you use ALREADY composted pine bark mulch, you won't have to boil, irradiate, neutron blast, or otherwise treat it.

I used composted pine bark for years in my bonsai soil. It is sold as "soil conditioner" in 25 lbs bags at Home Depot--"Nature's Pride Soil Conditioner for clay based soils" It is made of 100 percent composted pine bark. I used it straight out of the bag. Had no problems...I stopped making so much soil a while ago because it was a pain in the butt.

I've done a little research on mulches--there are no real concerns about phytotoxicity. There had been concerns about CEDAR mulch toxicity (because of its aromatic oils), but a University Of Missouri study proved it wrong. It also found that pine bark decomposes more slowly than hardwood mulch.
http://ppp.missouri.edu/newsletters/meg/archives/v7n3/meg6.htm

Hardwood mulch, depending upon its source, apparently can contain higher concentration of heavy metals (although hardly alarming concentrations) and might be more prone to spreading fungus.

 

[Jessf]

I'm not really interested in sterilizing the bark; that would be futile anyway, I think, given that it would be quickly recolonized by this and that. As several have mentioned.

My thought is more to jump-start the whole process that goes on in composting. Composting does involve some breakdown, yes, breakdown that continues in the pot and eventually makes it necessary to replace the soil. Would boiling break it down too far, haste soil collapse noticeably? I really don't know.

The more I think about it, the more I suspect that the presence of phytotoxins is the thing one would need to be significantly concerned about in using fresh bark. I haven't had a chance to research those much yet -- anyone else?

Thanks for the suggestion about the ammonia, Gary.

so would boiling or baking kill the phytotoxins? Do the phytotoxins come back? Water boils at 212f so setting your oven to 212 should produce the same effect minus the water which swells the wood causing cellular damage. I would think of the two methods, boiling might do more harm than baking. You could also freeze the bark, but again freezing can cause cellular damage as well unless you can flash freeze it. I would say if the bark is already pretty dry, a low dry heat will cause the least amount of damage.

 

[Bill S]

If you bake it, either do it at someones else's house when they aren't around, or after your wife or mom leaves for vacation for a couple of weeks.

 

[mcpesq817]

I know this thread has been percolating for a while now, but I have to ask - why do you think you need composted pine bark in your mix anyway? With the exception of my bald cypress trees, all my trees are in 100% inorganic and do just fine. Boon also recommends a 100% inorganic mix.

If you do want to go with bark for your mix, this might be a source that is widely available in your area:

http://www.agway.com/catalog/home_and_garden/soil/potting/10206640_miracle_gro_orchid_mix_8qt.html

Not to dissuade you from trying, but personally, it strikes me that your proposed methods will be way too time consuming and a pain generally.

 

[treebeard55]

Jess, phytotoxins aren't living creatures: they're chemicals produced by certain plants to suppress the growth of neighbors, or the germination of other species' seeds near them. Presumably, heat that was high enough would break them down; or, the actions of the molds, fungi, arthropods, and killer rabbits -- oops, wrong thread again -- found in composting material.

Maybe you want to conduct a parallel experiment: bake some bark and then see how it performs? Just a thought.

Mcpesq, I know many now use and recommend strictly inorganic potting mixes. I'm just not ready to make that step, I guess!

 

[mcpesq817]

Mcpesq, I know many now use and recommend strictly inorganic potting mixes. I'm just not ready to make that step, I guess!

I can understand that. I was a bit skeptical at first as well, but after taking a repotting workshop with Boon, reading what Walter Pall had to say, and experimenting with a completely inorganic mix, I realized that you don't need organics in your soil despite what bonsai books will tell you. The only downside is that you have to probably water more often, but because it's very difficult to overwater using that kind of mix, watering is a lot more predictable as you can water your entire collection every day at the same time (sometimes skipping a day, sometimes adding an extra watering in the evening if it's very hot).

For what it's worth, I have had all sorts of species in a 100% inorganic mix without any issues - junipers, pines, maples, hornbeams, elms, etc. The only trees I use organic for are my bald cypresses, and I use kanuma for an azalea I have.

Anyway, I know soil is a touchy subject on here so I'm not trying to convert you. I just throw this out there for you as it seems like you're going to go through a lot of trouble to come up with this type of soil component. Good luck to you!

 

[Jessf]

Jess, phytotoxins aren't living creatures: they're chemicals produced by certain plants to suppress the growth of neighbors, or the germination of other species' seeds near them. Presumably, heat that was high enough would break them down; or, the actions of the molds, fungi, arthropods, and killer rabbits -- oops, wrong thread again -- found in composting material.

Maybe you want to conduct a parallel experiment: bake some bark and then see how it performs? Just a thought.

Mcpesq, I know many now use and recommend strictly inorganic potting mixes. I'm just not ready to make that step, I guess!

I picked up a bag pine barch mulch. I'll sift that then give it the baking treatment. I don't think we'll know right away but I'll keep you posted.

 

[Dav4]

Alright, I'm just gonna come out and say it...boiling or baking pine bark mulch to make it a "better" or "safer" component for your soil is a waste of time. Period. As I stated earlier, I've used pine bark mulch right out of a bag purchased at a big box store. I used it in flower pots with turface for hosta, maybe 50:50 mix. I used it in very large tufa planters with turface and grit, maybe 1 part of each, for dwarf conifers. Finally, I used it sifted in my bonsai soil, maybe 20-30%. ALL of the plants grew fine in their respective mixes. Feel free to do it if you must...if you are experimenting, then fine. However, I believe all it will do is make your house stink. When I think of all the things needed to successfully grow trees in pots, boiling or baking my soil just doesn't make the list.

 

[treebeard55]

... so I'm not trying to convert you. I just throw this out there ...

John Kirby is still trying to convert me, without being pushy about it either. We dinosaurs take some convincing sometimes.

 

[stacy allen muse]

treebeard, why not try rubber mulch??? Don't boil it though... I have often found that fungi on the roots is usually caused by an excess of moisture at the roots, I would add more grit, lava/pumice, peagravel, etc. To increase air circulation at the roots. I often with my ficus grow them in a tree/shrub soil from lowe's (which has pine bark, not sure if it is baked, boiled or smoked though?) with peagravel. Mainly because of availability, and it's cheap. Now the mixture I've found through trail and error, that seems to work the best is suprisingly almost 70% peagravel to 30% soil. This seems to let the roots receive plenty of air... I still only water them every other day, and that's outside in the part to full sun...