Too Much Calcium?
 

I've had a lot of poor results in recent years when I repot from moss to Orchiata. My problem is just "failure to thrive". I use some crushed limestone in the bottom of well-drained plastic pots and I've read that Orchiata is slaked with lime. Both K-lite and MSU-RO fertilizers have been tried over extended periods (I use RO water). It's not easy to tell how much water they want because the rocks in the bottom make the pots always heavy. I don't water when I can see condensation on the wall of the pot.

My difficulties have included Phals, Paphs, Catts, and Oncidiums. I was wondering if anybody else has had this problem, and whether there's such a thing as too much lime in the pot.

I believe, if the roots aren't wrapping the limestonr, most of the dissolved minerals from them are drained by the holes on every watering.

New Orchiata holds very little water. Lots of people take a while to learn new watering habits. Try increasing your watering - maybe a lot. Use a wooden cooking skewer to determine whether the medium is still wet deep down inside.
Using skewers to determine when to water

jmrathbun -

You are not very specific about the problems you are having.

Are the plants growing new roots, or not? Staying well hydrated, or not? Blooming, or not? Same problems with all plants, or are the Cattleya problems different from Phalaenopsis problems?

If you can be more specific about why you think your plants are not thriving, members here can be more helpful.

Photos would help as well!

Details
 

Instead of flourishing -- getting bigger every year -- many of my plants are regressing -- fewer and smaller spikes, fewer healthy roots, leaves withering and pseudobulbs drying.

I think you're not watering enough. That would account for what you describe.

water
 

You may be correct. I'll try more water and see what happens. I've always been afraid of overwatering; it seems the symptoms are very similar...

Since orchiata tends to be hard to hydrate, I agree more water (really better watering) is the place to start.

At each watering flush copious water through the bark to assure the roots are getting wet. Multiple (2 or 3) flushes in a row are beneficial. Each flush should be thorough enough to wet all the roots.

You still want the medium to be dry or nearly dry before the next watering cycle. For most plants this will mean watering 2 or 3 times a week.

John, don't be fearful of "overwatering". Water, by itself, is not an issue, and you can likely water heavily and frequently - if your potting medium is in good shape.

Where excess water becomes an issue, is when the medium is too fine and dense, either through the use of too small of a particle size to start, or if the medium has broken down. In those situations, water can be held in-between the particles, cut off the free air flow to the roots, and literally suffocate them.

That is an unlikely scenario with Orchiata.