Questions on bark

[ArronOB]

Its time to make some potting mix.

It’ll likely be mainly bark. Most references to orchid bark in the US seem to be fir bark. I don’t think I can get that, only pine bark, which is probably radiata pine being the dominant forestry species here.

I’ve seen references to pine having more resin then fir, although no explanation as to why that is a bad thing.

So what is the current thinking on pine bark - I did a lot of googling and the opinions were contradictory and unscientific. Is it resinous. Is the resin a problem. Does it have other problems. Is there a process to remove or nullify the effect of the resin.

I know there is plenty of information out there on this subject but a lot is poorly informed and I can’t necessarily distinguish the good from the bad. I know there are people here with good botany or science background whose opinions I can trust.

Cheers
Arron

[camille1585]

It's perfectly fine to use Pinus radiata bark. In fact Orchiata, a popular brand of rather durable bark used by many people, is made from pure New Zealand Pinus radiata bark.

P. radiata bark is harder, so more stable over time than fir bark, so is actually a better choice of bark. That being said, all bark is processed to an extent (I think steamed) to remove most of the resins which can be toxic for orchids. If you are buying P. radiata bark sold for use on orchids it will be perfectly fine, however if you are buying a big bag meant for landscaping purposes for instance, I'm not sure if those are treated in any way.

Maybe more knowledgeable people will chime in. All I know with certainty is that the tree species has bark suitable for orchids.

[ArronOB]

Thanks Camille. The pine bark available to me is likely to be landscaping bark. I imagined just picking out the ugly bits and just using the rest.

I wonder how exactly steaming removes the resin. It’s no problem to me to steam it - I have a steamchamber used for timber bending. I guess I’d just need to know what I’m trying to achieve, and therefore how long to do it for.

I have also read of people wetting it, heaping it up and letting it mature a bit. I expect they are trying to achieve the same thing but it doesn’t make sense to me to start with bark already slightly rotted.

Cheers
Arron

[rbarata]

When I use coarse bark (Pinus pinea and Pinus pinaster) I buy 20 Kg bags (I believe it's what you guys are calling landscape bark) and, looking at some of the non-bark debris I find in the bag, I don't believe it's treated in anyway.

So far I never had any issues for using it (except some occasional ferns and weeds growing).

[camille1585]

I was doing some reading up on the topic, and saw that while I remembered the steaming bit, it's actually for sterilization. I also found the process Orchiata undergoes. They don't compost it, precisely to avoid the bark starting to break down. It's quite interesting though it doesn't answer the question of using bark from large bags as is: Orchiata Aging.

rbarata- good to know that it can be used straight out of the bag. That would certainly be a cheaper alternative than buying lots of small and expensive bags.

I had bought a bag once with the intention of using it for orchids, but never got as far as questioning if it was usable in the current state or not. I opened the bag, and since it had been packaged damp, the bark felt soft and rotted, so I mulched some outdoor plants with instead...

[rbarata]

Most all the bags I bought were damp, some of them with water inside but it has to do with storing conditions, many times outside.
But if you sieve it you cam take out what's not good and choose different sizes too (with handling the bark breaks).

[ArronOB]

Thanks for the link Camille.

I’m always always a bit suspicious when people carry on in vague terms about toxins. I wonder what toxins they are talking about.

Nonetheless, it does remind me to check the ph of anything I might mix up.

I don’t have access to Orchiata. I would love to know to what extent their claim is supportable that the outside is softened but the inside is still hard?

I can’t help being suspicious of marketing types.
Cheers
Arron

[Ray]

I avoided bark for years, because it seemed to be unpredictable about when it was going to decompose. When Orchiata became available, I had heard glowing reports about it, so decided to give it a try.

It is "the real deal". Probably the best bark potting medium on the face of the earth. It is size graded beautifully, so if you pick one appropriate for the roots of the plant you are potting, the medium will stay airy. It lasts a very long time. For me 3 years is no issue, and I repot well before decomposition threatens the roots.

As far as steaming bark to remove resins, I am only familiar with Rexius brand, and they have steamed it to the point that the particles are dry, crumbly sponges that decompose quickly.

[Anglo]

I grew Cattleyas in wooden baskets of coarse fir bark for years with great success. My orchids spend most of the year outside in hot summer temperatures, and the fir bark held a good combination of air and moisture with daily watering. It has not worked so well in recent years because the quality and chunkiness of that fir bark has become more and more difficult to find. Now it tends to contain smaller pieces with way more inner bark and debris, and less of the corky-textured outer bark. This restricts air flow and also breaks down and becomes compacted more quickly.

I have tried Orchiata bark since then, but even the coarsest grade has not been very coarse, which is the main reason I quit buying it. Another problem I had was that it does not retain moisture very well, at least not when used in wooden baskets.

Three years ago, I first experimented with course pine bark mulch or "pine bark nuggets" from Lowe's, and have been using it as the main base of various media combinations ever since. This makes an extremely inexpensive orchid medium, but it's tedious to sort through a whole bag to collect the suitable pieces from all the rest. I go for the firm pieces of outer bark, saving both large and small chunks. Then the rest of the bag is used as regular mulch around trees and shrubs, just as it normally would be.

I rinse and steam the pine bark for about four minutes in a large pot just in case of any pathogens, bugs, or eggs that might be present, but have not worried about resin. If I find a piece with a visible resin deposit when I'm potting an orchid, I'll put that piece on the very bottom of the basket or maybe just break off the resinous part. Otherwise, I have not worried about resin because I have not seen any sign that the Cattlyeas have a problem with it.

One of the pros of pine bark it that it is much more rot resistant than fir bark. A con is that, like Orchiata, it does not hold moisture long enough in my growing conditions. I have been dealing with this by adding various things. I've tried mixing in some coconut husk chips or including a top layer of fir bark or even a bit of Sphagnum moss. I have found that what suits one orchid well may not suit others well. Even different orchids of the same species can have different preferences.

[Ray]

You can improve the water-holding capacity of bark with a little pretreatment:

Before use, pour a small amount of very hot or boiling water on it. Not a soak, but enough to wet it completely. Wait 15-30 minutes and repeat.

If you're dealing with bark already in use, water the daylights out of it, wait, and repeat.