Question on lithophytes and lime
 

I recently acquired a Phal. maculata and was informed that it is a lithophyte in nature and would benefit from a "top-dressing of dolomitic lime". I have a more generalized question on the use of lime/limestone in growing lithophytes.
What exactly does lime do for the plant? Is it used mainly to buffer the growing medium to prevent acidic conditions? Or do these plants have a higher-than-average need for the nutrients in the lime, ie calcium and magnesium?
Also, would it be better to incorporate the lime into the growing medium, with the addition of some limestone pebbles maybe, or would a periodic sprinkling of lime on top of the medium be better? Thanks.

Lithophytes grow on rocks and cliffs. The rocks and cliffs leach minerals out when the rains beats the rocks. When the water rolls down the mountain it picks these minerals up delivering them to the plants. Typical fertilizers we use don't include the minerals calcium and magnesium in an amt beneficial to an orchid. So indeed we need to supplement the plants. Lime can also buffer the medium and why I use hydrated lime mixed in water to soak my sphagnum down. Keeps it fresh and healthy. How you decide to use it depends on the urgency. Limestone pebbles are fine for maintaining fresh media over the long run and providing some calcium and magnesium to the plant. Much more effective in feeding those nutrients to the plant is using a Calcium and Magnesium fortified fertilizer which I also use with Peters Excell Cal/Mag. All my orchids love the Cal/Mag :)

RJ - How much hydrated lime do you use when soaking your sphagnum?

Is there a source for lithophytes? I've searched the net with genera names from "Orchids to Know and grow" by Sheehan & Black and come up with next to nothing. A few sources say some Dendrobiums are lithophytic. I'm in the Gulf coast, FL.

Angraecum calceolus

Bifrenaria atropurpurea
Bifrenaria harrisoniana
Bifrenaria tyrianthina

Brassavola nodosa

Corybas geminigibbus

Dendrobium bigibbum
Dendrobium kingianum
Dendrobium speciosum
Dendrobium williamsianum

Dockrilla rigida
Dockrilla linguiforme
Dockrilla striolata

Encyclia altissima

Laelia angereri
Laelia bradei
Laelia briegeri
Laelia cinnabarina
Laelia crispilabia
Laelia esalqueana
Laelia flava
Laelia fournieri
Laelia ghillanyi
Laelia itambana
Laelia liliputana
Laelia lucasiana
Laelia milleri
Laelia mixta
Laelia sanguiloba
Laelia tereticaulis

Maxillaria picta

Oeceoclades maculata

Paphiopedilum charlesworthii
Paphiopedilum niveum
Paphiopedilum stonei

Phalaenopsis maculata

Phragmipedium besseae
Phragmipedium fischeri
Phragmipedium kovachii
Phragmipedium schlimii

Pleurothallis johannis
Pleurothallis teres

These are but a few of them. There are some on this list that are strictly found as lithophytes. Not all on the list are strict lithophytes, however. Some may be listed as epiphytes as well, but be aware that although they are called epiphytes, some will really just be around the base or roots of trees. Yet others may be listed as terrestrial, when in reality the ground they grow on is mostly rock with some organic debris trapped between crevices; or the rocks may have dried grass or dried reeds with leaf litter on top.

Thanks for the list - the Sheehan & Black book does not mention species names. Has anyone tried growing any orchid in/on rock and is there a retail source for lithophyte orchids?

db - I can't think of a vendor who sells only lithophytes. There are many growers, myself included, who use various stone products to grow some of our plants both lithophytes and epiphytes. Just curious, what's the fascination with lithophytes?

Curiosity. There are large pieces of coral rock used as decoration here on Florida's Gulf Coast and one in our flower bed has deep indentations that would seem perfect for an orchid. Of course, it's too big and gets full sun but the idea of using a smaller piece with an orchid seems like a good idea. Unfortunately, I see very few lithophytic plants on the Web - mostly hybrids - and I am unsure about growing an epiphytic dendrobium, for example, on a rock. Orchids are a bit pricy and I don't want to attempt something that is obviously going to fail.

Encyclia altissima is a lithophyte from the Caribbean islands and grows on coral rocks.

It's a xerophyte and is an extremely slow grower.

db - a few years back, just to prove a point to a friend about how orchids would grow in/on just about anything, I mounted various orchids on a whole host of items including rocks, metal and even compact disks. As long as you supply the right amount of water, light and fertilizer, orchids will grow on just about anything. I think in your case, the biggest problem you will face will be satbilizing the plant while it attaches itself to the rock. I would love to see a photo of the rock before I offer any further advice.