Anyone using bark-only soil mixes?

the_yard_guy(6A)August 5, 2014

Hello all. I wanted to share some thoughts on possible container soil experiments and would appreciate hearing what other GW members think about this.

In addition to the pine bark/DE soil mixes I current am testing with my small white spruce seedlings, with good results BTW, I'm also thinking of testing three possible variations of pine/fir bark ONLY soil mixes (with dolomitic lime and a CRF added to each soil of course). If these soils would work then that means using only one ingredient to make a soil: pine or fir bark. Possible? Of course. Practical? We'll that's why I'm asking for input.

Soil #1 would be pine/fir bark screened with a 1/2" hardware cloth and would be similar to the 5-1-1 mix, except without the perlite and peat. This soil would consist of pine/fir bark 1/2" and smaller, down to very fine dust, so it would retain a considerable amount of water. Depending on the bark used the amount of fine material in this mix could change considerably. This soil could be used for any plants, trees, or shrubs that like higher amounts of moisture. This soil would last at least one growing season, but probably not much more than that.

Soil #2 would be pine/fir bark screened through both 1/2" and 1/8" hardware cloth. The bulk of the soil mix would consist of pine/fir bark between those two sizes, with small amounts of the retained fine (1/8" and smaller) material added to increase soil moisture as needed, depending on what plants are being grown in it. Again, similar to the 5-1-1 but without the perlite and peat, and the amount of find material changing depending on plant usage. This soil might last two growing seasons.

Soil #3 would be pine/fir bark screened through both 1/2" and 1/8" hardware cloth, with everything under 1/8" removed. The soil would consist of bark between 1/8" and 1/2" only. This mix should last two seasons and could be used for any plants that like very well drained soils.

Most likely I would experiment with these next growing season since it's already August and there would not be time to test plants this late in the growing season and get any meaningful results.

I'm not suggesting bark-only soil mixes are a valid alternative to the excellent gritty and 5-1-1 mixes used by many people here, just a slightly different approach worthy of a few experiments.

Any thoughts, comments, or suggestions?



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I use bark only on my Orchids because it dries out all to fast).

Even on some of my orchids, it dries out to fast..I usually have to add something that holds more moisture than just the bark or they desicate.


    Bookmark   August 6, 2014 at 3:46PM
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Mike: Appreciate the reply. Good to know others have tried using bark only as a soil mix. I have a 1 gallon container full of pine bark I'm using as a test. I soaked it overnight so I know all the bark is saturated. I plan on letting it set outdoors for a few days and then checking the moisture in the bottom (the root zone area) to see how wet or dry it is.

Of course this is not a real test since there is no plant in the container. I just wanted to see if it was feasible to use bark only for a soil mix.

Based on what you've said above I would probably need to keep at least some amount of the finer pine bark material in the soil mix in order to retain moisture. So this soil would end up being a variant of Al's 5-1-1 mix, just without the perlite.

Thanks for the note.


    Bookmark   August 6, 2014 at 9:19PM
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Hey, Mike! Hey, TYG!

I think bark alone would dry out too quickly, and I think you would take a chance of it constantly becoming hydrophobic... I'd want at least something that held a bit of moisture beyond that, unless you're home all the time to take up the slack for changes in sun, winds, drying air, etc... like a little turface, perhaps...

Like Mike, I keep my orchids in more than just bark. There's a bit of turface mixed in, some perlite... and they seem to like it. I don't have to soak them every day.

So far, I have a Dendrobium that's doing very well... and an Anselia... also doing good.

    Bookmark   August 7, 2014 at 7:25AM
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Jodi : Thanks for the info. I'll check the bark later today and see how it's drying. I'm sure that the top inch or two will dry quickly but if the bottom half of the container remains wet or at least damp then I'll have an answer to the experiment. As you said Jodi the answer might be too add a bit of Turface or DE to the bark.

I'll know more later today.



    Bookmark   August 7, 2014 at 7:36AM
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calistoga_al ca 15 usda 9

Think about the plant in the bark. Depending on the plant and the amount of foliage, it can remove an awful lot of moisture from the mix. As the plant fills the mix with roots it will be increasing demanding on more frequent watering. Al

    Bookmark   August 7, 2014 at 9:14AM
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greenman28 NorCal 7b/8a

The only plants that I have growing in pure bark are Orchid and Christmas Cactus.


    Bookmark   August 7, 2014 at 12:11PM
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Thanks Jodi, Josh, and Al for your comments and suggestions.

The prudent thing to do is to use mostly pine bark but add in some Turface or DE in order to retain enough moisture. In cool weather you might not need the extra moisture provided by the Turface/DE but in mid-summer when temps reach 90+ each day it will likely be necessary.

Thanks again.


    Bookmark   August 7, 2014 at 5:55PM
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I know it isn't popular, but I mix a decent potting mix which has peat in it, some perlite and bark. I'd say I use about 2/3 bark-perlite and 1/3 Miracle Gro or something similar.
All my potted dirt plants grow well in this and I've had no problems. It drains very well yet holds enough moisture.

I buy the bags of bark from Walmart and its inexpensive. I change the ratio depending on the plant.

With small plants you could add sphagnum moss to the bark to hold moisture, but that gets expensive for large container plants.

I'm a orchid grower and always have bags of both on hand.

Here's what I buy for large container plants. I admit, I don't screen or change the size of the bark. Everything gets mixed together. Easy.

Sorry for the feet :))


    Bookmark   August 7, 2014 at 10:07PM
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Jane: Thanks for the message. Last year I noticed that Timberline brand of mulch in my area but I have not see it anywhere this year. I made two trips to my local Walmart but both times they had no pine bark at all, but a thousand bags of cedar chip mulch however.

Your mix sounds good and very glad to hear it works for you and your plants. As long as they are happy, that's all that really matters. The fine line in these soil mixes is finding one that allows good moisture retention for roots without allowing standing water in the bottom of the container. Sounds like your mix of bark, perlite and potting soil drains very well.

I have friends who use straight MG Potting soil each year, sometimes even using the "moisture control formula", then water their containers daily, regardless of soil conditions, and wonder why the leaves of their veggie plants always turn yellow by mid-summer. Of course by that time the bottom half of the container is nothing but a soggy mess, like a bog or swamp.



    Bookmark   August 8, 2014 at 7:53AM
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I'm not trying to change the subject, but why do self watering containers work so well and they always have wet feet?

    Bookmark   August 8, 2014 at 12:52PM
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greenman28 NorCal 7b/8a

Root tissues differentiate between air-roots and water-roots, which is why hydroponics are possible. Self-watering container plants have both, with the water roots usually diving into the reservoir at some point.

This is different than a compacted soil in a traditional container setting.


    Bookmark   August 8, 2014 at 1:46PM
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    Bookmark   August 8, 2014 at 2:17PM
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garyfla_gw(10 Florida)

I follow Janes recipe except I use some of the timberline
top soil Too much water is MUCH more of a problem for me I add a layer of canadian peat to the top to slow down evaporation during dry season. Don't use perlite as they end up in the compost bin when repotted.
i grow almost all my orchids mounted except for the floofy catts those are in crushed lava and in hanging pots.
as you can tell I'm a waterer !!! lol Most of my cactus are mounted also but those in pots I use fir bark fines along with leca . No I didn't buy it was a gift from a neighbor . Don't really see much improvement over lava at about 4 times the cost . I do grow my annuals in pine bark fines worked into my sand and seashells lol . So not pure by a long way lol Good luck with your experiment about the only way you can find what works for you??? gary

    Bookmark   August 9, 2014 at 4:30AM
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