It works fine for my orchids. I use fir bark but cannot Imagine a drainage problem, at least not for the first few years. Al

Al : Thanks for the reply. I know many orchid growers use fir bark and that thought came to me as I was screening the PB.

I know fir bark holds up longer than PB but the basic idea (using bark only ) would make sense if the drainage and water retention issues were balanced and I use lime to boost the low pH of the bark.

Thanks for the feedback.

TYG

Like Al, I've used pure bark (fir bark) for Orchids and Christmas cacti. I screen the bark to eliminate the fine dust and control the particle size, which really allows you to dial in drainage / flow-through rates.

I also had a fig tree in nothing more than bark and a little perlite, and I've collected maple seedlings and plopped them into bark and perlite (with some Osmocote). Very effective for these plants.

Certainly not as effective for all plants, but good for a range of species / types.

Josh

Josh: Thanks for the info. When I screened this PB I ended up with a very nice pile of 1/8" to 1/2" bark. Since I use 2 screens at once I also had a good batch of fine PB, 1/8" and smaller.

My thought was to try the PB in a container and determine how much water it retains. If I need a bit more water retention I can add some of this fine PB material. If the PB holds sufficient water in the root area without perched water then I would leave out the PB fines.

I'll use a 1 gallon container as a test and water it heavily for a few days, then see if it holds too much, or not enough, water for growing purposes.

I believe PB should last a couple of seasons, especially if I leave out the fine material.

Sound reasonable?

TYG

Yes, sounds reasonable. Definitely do your test.
Pure bark should have about the same moisture retention curve as peat moss, though, and will have a perched water level.

Josh

Josh : So if the PB will retain perched water then perhaps a wick as Al and others have described will be necessary.

I'm assuming the perched water is due to the lack of perlite or granite?

Exactly.
Of course, even with a bit of perlite or granite, there will be *some* perched water. However, the mix will drain better and won't retain as much water to begin with, either. I think you'll find that sweet spot for your container conditions.

Josh

BTW, if I do try using PB only the pH will be very low, somewhere between 3.5 and 5. I'm wondering if the standard 1 Tbsp of lime per gallon of 5-1-1 soil would need to be increased a bit to compensate for the lack of other ingredients in a bark-only mix.

Thanks.

TYG

That should be enough Lime for the bark.

Josh

Thanks Josh. I'll give this a try. I really do not mind adding granite or perlite to the PB, but I enjoy seeing what these soil components can do in various combinations.

I'll soak some screened PB and then run a test to see about how much water it holds. I'll post the results so that anyone interested can have the information.

From what you've said I probably would not want to add much, if any, of the fine (Thanks.

TYG

One other thing you might notice is that the top inches dry out quickly, while the lower inches remain saturated. That fine bark dust would help even out the moisture, similar to the peat in the 5-1-1...but with the fine dust, the moisture retention increases, perhaps to an unfavorable level.

Josh

Yes, exactly. That's the fine line with these soils: keeping sufficient moisture and nutrients available to the plant roots but, at the same time, making sure not to keep the soil saturated and reduce oxygen levels. A delicate balance!

TYG

That's why I like using DE, it if not filled with water, DE retain loads of oxygen. I'm beginning to think though both perlite and DE would be better. I need to try that. Also every link on studies, and experts say lime takes months to work. I myself use compost to balance PH. I add lime anyway, but not sure it is working? My ph soil tests show little change with the addition of lime. A definite hike in PH with compost. Mushroom compost seems even more able to swing PH. I'm not buying anymore lime once it's gone. I bought some to make 5-1-1 which I used for experiments, and I do like it for trees, but that's about it. Experiments mentioned elsewhere show better results using other mixes for various species. Nice to see though others do understand every species is different.

Last night I screened some fresh PB and filled a 1 gallon container. I then placed the PB in a bucket of water to soak. Since the PB was fresh and not composted it was a bit hydrophobic so a good overnight soaking will solve that. My goal is to get an idea about how much water the PB retains without any added perlite, DE, granite, etc. I'm also curious about how fast the PB dries out, although that's hard to know without a plant in the soil and would be variable depending on the weather.

Obviously this is not meant to be a scientific test but I just wanted to get a feel for what would be involved if using only PB as a container soil.

Thanks everyone.

TYG