Why I think bark is the worst media for orchids

[ChrisMalaga]

I've been growing orchids for 10+ years, with ups and downs (moved to another country, lost many, had a time when I thought I would stop growin orchids, now I'm back, some are still with me after 10 years...) and, as many people, I've been using mainly bark for my orchids. I've used of different qualities (from decorative bark chips where I had to select the best chunks manually, to superior grade bark from orchid nurseries, but never Orchiata, so I can't really speak about a substrate that costs more than orchids). I usually use medium sized bark, fine bark is "better" at some things (retaining moisture, wicking, etc), but suffucating for large roots. I'm now considering that most of my bad experiences are related to this media. I will explain why and also my final conclusions about what is really wrong with bark, at least for me (everyone has a different environment and techniques and I'm sure many people will disagree 100%):

- new bark doesn't retain enough moisture. Things get better if you soak it before use and if your watering technique is soaking, especially for the first months. When bark starts degrading, it will retain more moisture... until it's too degraded and acidic and it's time to change it again. I hate soaking plants, especially considering water is so expensive in my area and ecologically wrong to throw water, and also time consuming.

- moisture is very uneven. Bark is not a really wicking material and a wet area remains wet, but you can have dry chunks beside and they will remain basically bone dry.

- it is hard to tell when to water your plants. Now this is a big NO for me. I've made tests, putting bark in empty pots, watering and leaving it there for a week. Then I checked the medium: while the top and side layers were visibly dry, due to evaporation (I always use pots with side holes), the core was still wet. You cannot see in the middle of the pot, so you need to guess. Droplets are visible on transparent pots? That really depends on temperature, you can't rely on droplets either. And still: some parts of the medium will probably be bone dry, even if you see droplets.

- it allows the creation of small water pools in the media, where bacteria can proliferate and water can suffucate roots. This happens especially with medium and large sized bark and is related to the biggest fault bark has, in my opinion. It also has to do that it's an organic media which is also a good environment for pathogens.

- now the biggest fault. The SHAPE. Bark has an irregular flat shape (there is less flat bark, but more or less, it's flat pieces). When you put bark in your pots, it can be aligned vertically, horizontally or somewhere in between ("obliquely"? English is not my first language, sorry). Unfortunately there is no control over how those pieces will be aligned, unless you want to put every single little piece of bark in your pot with extreme care, which is close to impossible. When a flat surface is positioned horizontally, water will sit on it for an undetermined amount of time, depending on your temperature and evaporation rates. This is especially true with new bark, which is less moisture retentive. I find this to be maybe the biggest reason why I've had problems with bark. A huge drop of water sitting for hours or days on a piece of organic media, has caused many pathogens to proliferate in my experience. How do I know if there are huge drops sitting in the middle of the pot where I cannot see? I can't know, but I'm sure there will always be.

One of the solutions I've tried was to add other material to bark: sphagnum, leca, pumice, perlite. While these can improve the situation to some limited extent, why should I add something to improve the material, if this material has so many faults and will also degrade faster? I prefer adding sphagnum to something else (leca, scoria, etc.) to tweak something that already works, than trying to find a solution to something that doesn't.

This is why I'm growing less and less orchids in bark and having more success with alternative media (leca, scoria, pumice and even sphagnum). I don't know if other people will share my experience, but I still find incredible that 99% of people use bark, with so many downsides. I know it's my personal experience though.

[SouthPark]

I know what you mean! I'm a scoria fan myself. But a lot of my orchid friends - that are very good and experienced orchid growers ------ use bark/perlite mixes.

I think the main thing is to figure out how to make the media work nicely for our growing region ----- working nicely for the orchid and for ourselves, over long periods of time.

With bark ----- I have read that filaments from some sorts of fungus that can make some bark in pots become water repellent ----- which makes water run straight through the pot, leading to dehydration ----- and worse. One way to detect that sort of thing --- is to hold the pot a bit sometime after watering -- to see if the pot is super light (when it should not be).

[Fairorchids]

Based on your comment that bark is 'flat', I think you have been using bark that is too coarse (large), and possibly bark that was not intended to be used as growth medium for orchids.

I mix my media from base ingredients. For most non-Cattleya & non-Cymbidium, I use a spaghnum/bark mix (probably 4:1), fingertip tight in the pot. This is the most moisture retentive combination, that also allows decent air through the root zone.

For Cattleya, I use bark/charcoal/perlite in 2:1:1 ratio, BUT:
Small plants: 50/50 seedling size (abt 3 mm) and mature size (abt 12 mm) bark nuggets.
Large plants: All mature size bark.

Then, to balance the drying period (so I can water everything on the same schedule), I select either plastic or clay* pots. * = never with holes, they dry out too fast.

In view of your comment about water cost, you might consider going primarily with spaghnum. Cattleya grow fine in the spaghnum/bark mix also.

[ChrisMalaga]

Yes, I've been using decorative bark many times, I admit it. I select the best pieces manually. But I've also used bark from orchid nurseries, many times. I've never used Orchiata, which I know is the Cadillac of barks, but definitely too expensive. However, from what I see from YouTube videos and images on the web, it has some degree of flatness.

I've been using scoria for Cattleyas and Brassavolas with excellent results. Yes it dries fast in summer, but spraying some water is not a problem, as long as I don't have to soak a huge pot to ensure that it's evenly moist, I can also flush from time to time. At least I know the humidity will be distributed evenly, because that material is wicking, and it's incredible how it solved possible rotting issues. For those orchids that need more constant moisture I'm now using self watering with a mix of leca, scoria and pumice, it also seems very promising so far. I've recently put a Cattleya in self watering and will check how this goes. For some miniatures I use different mixes, my Ceratostylis philippinensis for example is in a self watering pot with sphagnum and perlite.

I'm not sure if the idea of using bark to "simulate" natural conditions makes sense to me. Orchids grow mounted, a huge vertical piece of bark has totally different properties from smaller pieces inside a pot. I've always found it tricky to grow orchids in bark, but I know it's the most common media. I wonder if beginners have failed with some orchids for my same reasons and have never doubted it could be because of this media, just because it's the most common option.

[Clawhammer]

You have some valid critiques, thanks for taking the time to share your experiences and what you have found works best in your conditions.

In regard to the shape, I find that a little confusing. I do use orchiata (perhaps it is cheaper here). What size of bark are you using? I think the air pockets created by the irregular shape is a feature, not a flaw for the roots. Also, stating the obvious, most of the orchids we grow attach themselves to bark in nature.

[ChrisMalaga]

Originally Posted by Clawhammer

In regard to the shape, I find that a little confusing. I do use orchiata (perhaps it is cheaper here). What size of bark are you using?

I use medium sized bark most of the time. Finer bark is much better at distributing humidity evenly, especially if you water from the top like I do, and avoids the problem of those little pools of water, but it can't be used with every orchid. Larger sized bark definitely doesn't work with the way I water: I water from the top and can clearly see that due to the irregular shape of bark, some pieces of bark at the bottom will never see any water because the bark on the top blocks the water from reaching them. At the same time, some huge drops will form on the surface of those that are placed horizontally and stay there far too long, especially in winter.

[Orchidtinkerer]

hey chris,
that's some good observations.
My take on it is that bark is either people's favourite subrate or it isn't.

I've converted to pumice and lecca - for exactly one of the reasons you descibe, I just cannot tell when to water with bark.

Bark can also dessicate roots as bad as lecca can if you let it dry out excessively and bark can dry instantly at times. If you aren't there to rewet it. I try to avoid it too.

Maeks no good economy long term, needing more repots and causing damage if you delay a repot.

The wicking point is also valid, bark tends to accumulate water at the bottom while the top dries. This has cost me some orchids with not many roots as the roots are all near the surface and the water stays at the bottom.

But there are differnt qualities of bark and I should point out I have never tried the orchiata which gets more praise than other brands so maybe it was the quality of bark I was using.

[SouthPark]

Originally Posted by ChrisMalaga

I wonder if beginners have failed with some orchids for my same reasons and have never doubted it could be because of this media, just because it's the most common option.

Yes - absolutely. Not just beginners have 'failed' ------ but regular orchid growers have as well ----- mostly due to not having converged on a system (watering schedule, media size, pot size height and diameter and number/size of holes at the bottom of the pot, temperature, lighting, humidity, air-movement etc). This pretty much goes for any media.

Because we see and know growers successfully grow orchids using bark, or bark/perlite, or scoria etc etc ...... then we know that they have a working system. So the aim will be to either find out their strategy and methods, and also take a look at their growing environment ------ or to figure out for ourselves what needs to be done - to make the best out of what we have.

The system also includes knowing what to watch for or cutting down on orchid deaths due to things like mites/scale/fungus etc. Some mites/scale/fungus can cause fast or even slow death of orchids ------ leaf and/or root attacks etc.

[Roberta]

Bark quality is certainly an important factor... And it changes, since for the most part it is a byproduct of lumber production. If trees are grown in "plantation style" with rapid production and harvest, the bark is likely to be less good than from older trees. If it breaks down in a couple of years, not good. I do like Orchiata -it is very hard, and I have found that it is still in good condition 4 or 5 years out. Generally I have to repot sooner since the plant outgrows the pot. But it is on the expensive side... fortunately I have a local source so that I don't have to pay shipping (which would price it out of my market). But also, it works for MY watering regimen. (I don't get much rain, plants dry out fairly quickly) It may not work well at all for those with high humidity and lots of rain. Actually, the medium is just the means to reach a goal, which is "humid air" around the plant roots. Lots of inorganic media do the same with suitable watering. Or wine corks or... you name it. It is the goal that is important, how you get there is dependent on your conditions.

[Keysguy]

I use fir bark exclusively for my Catts and other large root orchids. Depending on the size of the plant it's either medium or large sized but always with a handful of large chunks in the bottom to promote good drainage. Even down here outdoors year round I only repot when the plant has decided to walk away from the pot and that's typically 3 years on average.

I use some sort of mix on all my other types and all of them contain some amount and size of fir bark.

When I repot, the old bark makes nice mulch for my trees.