Sphag vs. Orchid Bark vs. Lava Rock

orkid15March 11, 2007

I currently have my Phal in Sphag moss. I was wondering, from your own personal experience, what is the best potting medium/substrate used to grow Orchids in?

Ive heard Sphag holds water better and longer, Orchid/fur bark stays humid for almost the same time and is almost the same as Sphag, and Lava rock I would assume is good b/c its porosity can also contain pure water that can feed the orchid roots for quite some time.

My question is, from your experience, what do the Orchid roots like more? Do they like sitting in Sphag, clinging to Bark, or clinging to the lava rock?

What do you all have the most success using??

I know that different species of orchid have different requirements, so for the sake of argument, please lets stay focussed on Phals.


p.s. I would think there is more risk of root rot using sphag and bark, than with Lava rock??

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aachenelf z5 Mpls

Whatever you decide to use, I think it's better to take advice from someone in your area and with your conditions. I love lava rock for a lot of things, but I'm in MN. Granted our summers can probably rival yours, but that's only for a few months. Temps, amount of light, humidity, what you grow etc. all play a part in what will probably work best for you.


    Bookmark   March 11, 2007 at 1:06PM
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I agree- every grower is a little different in how they treat their orchids. I am also in Florida, and can tell you that mine do well outside in my lanai, under the overhang but they do get some morning sun since we face east. I grow them in a mixture of sphag and bark, but mostly sphag, and find this works the best for me. It's pretty easy to pick up a pot of sphag and be able to tell right away if it needs water because it is SO light! Compare that to sticking your finger down into bark to try and tell if it's still moist? I haven't had problems with root rot. It also helps to put a few of those little "popcorn" packing things in the bottom of the pot for extra good drainage.

Good luck! Florida is a great place to grow many different kinds of orchids!

    Bookmark   March 11, 2007 at 1:15PM
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johnndc(Wash DC)

I tried numerous different methods, and found that for me one method worked better than the others - not going to tell you which because... as the others have mentioned, it will totally depend on the conditions where you live, even your particular home, how you water, etc. I think you should consider trying a few different ways - sphag, bark, chc, and semi-hydro. See which one seems to work best for you over say a year.

    Bookmark   March 11, 2007 at 8:23PM
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howard_a(z6 NYC)

"Orchid/fir bark stays humid for almost the same time and is almost the same as Sphag, and Lava rock." This is not what the majority of orchid experts believe. Sphag holds at least 10X its weight in water and some brands boast 20X. Bark holds around 3X its weight maybe 5X when old. The volcanic rocks vary a lot from Perlite, the most absorbent to some Aliflor's which are the least. None should be worse than 5X or so. For the home grower the best strategy for a potting medium is only rarely a single type of material used "straight" but some kind of blend because these materials all have different weights, ph's, lifespans, etc. For instance although a combination of bark/lava rock doesn't hold much more water than either by itself, bark does age (breakdown) while lava rock does not. Although it might seem like a bad thing, the slow aging of bark usually results in some amount of nutrition being supplied to the plant in the form of trace elements and barks ph is usually slightly acid vs lava rock which is usually inert. For phals an all sphag mix can work but it is best in a clay pot and with other cultural variables at optimal levels. In a plastic pot and in less than excellent light then a mix of sphag and bark is somewhat more forgiving than pure sphag alone.


    Bookmark   March 11, 2007 at 8:46PM
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olyagrove(z9 Tampa, FL)

Growing roughly 400 orchids outside, in Florida, I love sphagnum moss. It works great for phals, and even catts (!)

But, like everyone mentioned, it is all about your conditions. I grow outside, with lots of rain in summer, and lots of light throughout the year.
I put almost everything in either clay pots or open baskets. With phals, I plant them in these:

and then hang them slanted, on a single wire. The amount of sphag is thus minimal, and I can water every two days no problem. The reason it matters is because when rain season comes, with rain for three-four afternoons in a row, the plants can take it without any rot.

Another big favorite: tree fern fiber and chunks. I mount a lot, and throw big chunks of tree fern into large catt. pots.

For example, this orchid:

has chunks of tree fern (cubes with sides approx 8-10 cm) , lava rock chunks and some packing peanuts. Not much medium at all, and lots of holes and drainage :)

To summarize, this is all a matter of experimenting and observing. More than 6 years of growing outside in Tampa, I am still tinkering and adjusting. It is fun :)

    Bookmark   March 12, 2007 at 8:54AM
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I started a few years ago using bark but I started switching over to Long fibered moss last year. Stays moister a lot longer and my Oncs. seem to love it. Repotted my little "Earth Star" phal in it a few weeks ago and a few Dens will get it soon. Bark dried out too fast....


    Bookmark   March 12, 2007 at 3:56PM
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Well I ask because Ive had my Phal in sphag moss since I bought it a year and a half or so ago. Havent seemed to have a problem with it.

Recently I moved the phal outside (2 leaves, no spike, lost it flowers and i cut the spike last Aug) after repotting it. Ive noticed that outdoors down here in Miami the sphag stays humid waaaaay longer than indoors. I only need to water once a week, where as inside after 3 days it would be almost bone dry.

I havent seen any new growth yet, although the center where the leaves connect is turning a brighter green, almost as if it is going to sprout another leaf hopefully.

Ive seen other phals planted in bark/lava rock/ and even these weird looking balls (almost like tiny coconuts) and theyve all had success. I thought maybe my phal isnt too happy in the moss. But the leaves are a nice color, and very strong so, maybe im just impatient. I think its alot happier outside in the warmer air and shaded eastern sunlight. We'll see what happens!

p.s. its potted in a clay pot with strips along the sides for good aeration and drainage. Not too tight in Sphag. I allow to dry completely before I water. I empty out a bottle of purified water onto her (zephyrhills) and allow her to drain completely. Then I lightly mist with a mixture of pure water/20-20-20/SUPERthrive (all diluted into a gallon of H2O). And let her do her thing!

    Bookmark   March 12, 2007 at 5:35PM
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howard_a(z6 NYC)

Just FYI, the phal now outdoors should be drying out waaaay more than it was indoors. Temps are higher, ventilation is about 1000 times better and light is (should be)10X better. Adds up to near daily watering for an average (6") pot. A little shade goes a long way. Shade is the enemy. It is a neccessary evil. One only uses enough shade to get the job done, no more. How much is that? It really depends on factors I cannot know. But you can. Some sun is very important say an hour or two of that morning east sun should have minimal shade.

You are also starting off your orchid growing career with habits that are going to be unsustainable in the long term. Have you done as others have suggested and located a couple or few good orchid reference books to get the basics down with a minimum of bad habits?


    Bookmark   March 12, 2007 at 6:43PM
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Well, I have to state here that when I move any indoor orchids in Sphag outdoors, they tend to not need as much water also - and I am down here in Florida like you. That may not be true up in Zone 6, but the important point here is that, as people have said above, it's all about trying to see what works the best in YOUR particular growing situation. What may be a "bad habit" in one area may be great for your orchids in another! Just learn to tell what a plant looks like when it's getting too much sun, too much/not enough water, and common diseases like scale, mites, and fungal diseases (here in Florida, I've found fungal diseases pretty common on my orchids in the pool cage - especially now, when it's humid but cool....)

So keep records, pay attention to your plants, and "experiment" a little to see what works best for you!

    Bookmark   March 12, 2007 at 7:06PM
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I agree, the humidity down here in Miami is insane. So, although it may be warmer and there is more ventilation, the humidity keeps the substrate a little more wet for a little while longer.

    Bookmark   March 12, 2007 at 8:06PM
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Just would like to comment - 2 leaves, in a year and half, is not a very good sign. You need to follow Howard's advice and get a few basic books on orchid growing. It's impossible for anyone to know your growing conditions and habits. With all the fertilizer you are using, you should have had leaf growth by now. I would suggest stopping spraying, cutting back on fertilizer and increasing the light levels.


    Bookmark   March 12, 2007 at 11:45PM
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highjack(z6 KY)

Stop misting the plant with h2o, fertilizer and superthrive. In Miami you have enough humidity and don't need to add more. Please get a book, read about your orchid and relax, if you have healthy roots, leaves and sun from the east, you will get new growth. It won't happen in the two weeks you've had the plant outside. I also suggest you buy a couple more phals to watch and take the pressure off your current one. You know the old saying, a watched (phal) pot never boils (or grows).


    Bookmark   March 13, 2007 at 7:40AM
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What are you using to drill holes in the clay pots? Nice!

    Bookmark   March 13, 2007 at 10:07AM
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orchid126(z6, NJ)

Foliar feeding all the time is no substitute for a good drenching of the roots with fertilizer. Besides, orchids don't take in much food from the top of the leaf. If you do foliar feed, do it on the undersides of the leaf where it will do the most good.

    Bookmark   March 13, 2007 at 4:00PM
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Cyanea(z11 HI)

I've used gravel for Phals before (it's heavy the plant wont topple over, and I was worried about overwatering). They send out spikes but the flowers come out ugly. For my Phals now I like to use sphag in a plastic pot. Besides water retention (less frequent watering), it is easy to tell by weighing a sphag filled pot to tell if the plant in it needs watering (which is why in certain situations - like growing Phals - I prefer sphag over bark).


    Bookmark   March 14, 2007 at 2:11AM
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