Potting Medium

[aerides]

I've recently received paphs from the same vendor potted in two mediums: sphagnum (probably recently imported in that medium) and smaller grade bark mix (the vendors choice). Personally, I prefer sphagnum as a potting medium because I can tell when it needs watering, and because dries out evenly, top to bottom. The bark mix does become lighter when it needs watering, but it doesn't seem to dry out as evenly (it can be dry in the top half and moist on the bottom, especially in those taller-than-wide rectangular pots that seem so favored for paphs). Is either one of those mediums okay, or is one more appropriate for some species than others? Or is the bark mix actually better in general for paphs than sphagnum, whether I like it or not? Thanks!

[MrHappyRotter]

Use what works best for you. There is no best and "better in general" may be meaningless in your situation.

Moss tends to decay faster than quality bark, but then high quality moss will potentially hold up better than low quality bark. Bark tends to allow a bit more air around the roots and is slightly more forgiving for people who over water. Moss tends to be more acidic, and tends to stay more moist, and is also a bit better for encouraging live moss to grow.

From my perspective, it seems more people choose to pot in bark because pure moss is trickier to water in a lot of common growing situations, particularly for plants in larger pots.

There's also no reason why you couldn't use a combination of both. Lots of growers use mixes that combine several different ingredients together instead of using one single component.

[aerides]

Originally Posted by MrHappyRotter

Use what works best for you. There is no best and "better in general" may be meaningless in your situation.

Moss tends to decay faster than quality bark, but then high quality moss will potentially hold up better than low quality bark. Bark tends to allow a bit more air around the roots and is slightly more forgiving for people who over water. Moss tends to be more acidic, and tends to stay more moist, and is also a bit better for encouraging live moss to grow.

From my perspective, it seems more people choose to pot in bark because pure moss is trickier to water in a lot of common growing situations, particularly for plants in larger pots.

There's also no reason why you couldn't use a combination of both. Lots of growers use mixes that combine several different ingredients together instead of using one single component.

Thank you very much. So I won't be repotting the paphs I have in the bark mix immediately and I feel encouraged since it seems to work for many people. Maybe I got "burned" once and shied away from it too soon. Re: pH, I don't know if this is correct, but I read that sphagnum is pH neutral and peat is acid.

[Roberta]

Originally Posted by MrHappyRotter

Use what works best for you. There is no best and "better in general" may be meaningless in your situation.

Moss tends to be more acidic

I use small bark for Paphs, and so does everybody else that I know that grows them... I had not thought about the acidic tendency of sphagnum, but that might be a show stopper. Paphs tend to like neutral to slightly alkaline environment. I know that many Paph growers use dolomite lime, oyster shells, or other source of slow-releaase calcium(and slightly alkaline) top dressing on Paphs. The Huntington Botanical Gardens uses city water or well water (pH close to 8, high calcium) on their world-class Paph collection, having found that the plants do better with that than with RO water.

Sphagnum is used on imported plants that need moisture (so can't be shipped bare root) because other media are not permitted. For Paphs, probably not a a good long-term solution.

[aerides]

Originally Posted by Roberta

I use small bark for Paphs, and so does everybody else that I know that grows them... I had not thought about the acidic tendency of sphagnum, but that might be a show stopper. Paphs tend to like neutral to slightly alkaline environment. I know that many Paph growers use dolomite lime, oyster shells, or other source of slow-releaase calcium(and slightly alkaline) top dressing on Paphs. The Huntington Botanical Gardens uses city water or well water (pH close to 8, high calcium) on their world-class Paph collection, having found that the plants do better with that than with RO water.

Sphagnum is used on imported plants that need moisture (so can't be shipped bare root) because other media are not permitted. For Paphs, probably not a a good long-term solution.

Thank you, Roberta. All of that is very interesting and informative, particularly your comments about water, Huntington and calcium supplement. Ref. my last post, I've read that sphagnum is pH neutral (as opposed to peat). I've used it for years for various orchids. It's a solid old-school choice for orchid potting medium, not just for import purposes. Environment would matter - it may not work as well in greenhouses due to high atmospheric moisture content. But it's wonderful in the house. If it's used correctly, it's reasonably open, even directly after watering but does require a little technique. Nevertheless, you zeroed in on my real concern and underscored it perfectly - that paphs prefer neutral to slightly alkaline medium. Would Cal-Mag supplement be beneficial to otherwise pH neutral medium? Thanks again! I love paphs, and want to learn as much as possible about growing them well.

[Roberta]

If your water is very pure, Cal-Mag is important on general principles. But I don't think that it will do much for pH - I don't know for sure which calcium/magnesium salts are used, but if it's the nitrates (very likely) it's going to be pH neutral. The slow-release calcium-supplying top dressing will probably do more to shift the pH. (Of course its efficacy is also a factor of the water - where I live, it is pretty useless because there is plenty of calcium bicarbonate in the water, sitting at pH 7.8 or so) But it does make sense, many Paphs are native to areas with limestone cliffs.

Brandon Tam, the orchid specialist at the Huntington, wrote an article in the current Orchid Digest (whole issue devoted to Paphs) discussing many aspects of Paph culture, including the water. In general, a terrific publication well worth the subscription. The Orchid Digest Publication

[aerides]

Many thanks!

[Ray]

All my paphs and phrags do very well in semi-hydroponics.

[aerides]

Originally Posted by Ray

All my paphs and phrags do very well in semi-hydroponics.

How interesting! I've never gone down that particular paph-path. I'll have to read up on it. Do you have a large paph collection? Sounds like it.