C. mossiae

[Frdemetr]

It's very usual to grow orchids on stones (not s/h) in Brazil (when weather is humidy, or with automatic misting systems). Fren posts the major advantaje (the roots never rot). Stones are not neutral, and this fact could harm the plants:
1) "Brita" (I don't know the word in english, the tritured rock used in constructions to made concrete) is made from granite and gnaisse are acid, and Laelia lobata, some Cattleyas grow well. Some rupiculous Laelia loves basic rocks, like calcarium, and do not grow well in "brita"
2) Acid or basic, the stones must do not have sulphur (in any quantity)
3) As I posted before, nitrogen is the great problem, if one uses only stones he or she need to mist a solution with more proportion of this nutrient
4) Do not hang the pots, they are to much heavy!

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[Ross]

If one subscribes to the philosophy of fertilizing during every watering, nitogen washing away can be an advantage with stones because there would be less chance for mineral buildup (I would think). With no appreciable breakdown of the medium, repotting would be less frequent. Also, for naturally top-heavy plants like certain specimen sized Brassias or Oncidiums, having heavy pots could be an advantage.

[Tindomul]

What size stones are being used? This is very interesting. The one thing I dislike about S/H is the mineral build up.

[Frdemetr]

Crushed stones (aggregates) from 0,5 to 4,0cm in the main measure are used; little quartz rounded stones, founded in the sand, are neutral and can be used in a great number of orchids (+/- 0,5cm diameter). Vulcanic (basalt) stones are alcaline and works for brazilian rupiculous laelias. I had bought orchids poted in stones (non-s/h) with healthy & happy aspect, but I repot all (I don't have automatic misting system)

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[Sharry]

FYI:

The stone is crushed granite which would be acidic correct? I guess most epiphytes would be growing in a neutral environment. Maybe after enough detritus accumulates around the roots, it gets acidic. t

Thanks for the interesting pointers.

[Tindomul]

Originally Posted by Sharry

FYI:

The stone is crushed granite which would be acidic correct? I guess most epiphytes would be growing in a neutral environment. Maybe after enough detritus accumulates around the roots, it gets acidic. t

Thanks for the interesting pointers.

I would tend to agree, but after a nice rainstorm, the pH would probably go back to normal 7 or so.

[Frdemetr]

I want to clarify an important point: I don't use crushed stones media, or any gravel, quartz or similar media. I just post the conclusions (right or wrong) that I've reading in brazilian papers and in the "brazilian list" of orchids in Yahoo! (orquideas : Mundo Orquidófilo portuguese only). I agree with you, Sharry; when I use tree-fern fiber media in brazilian rupiculous laelias, the media becames acid with time, and the laelias still grow and bloom (at least for two or 3 years, than I need to change the media). BTW, I've seen the same specie of laelia (eg, Laelia caulescens) growing in neutral or alcaline stones with double size and triple spikes and blooms!! So, if I had automatic misting system and a covered orchidaruim (I grow outdoors), I would try crushed stones media.

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