Potting large Cattleya in low humidity?

[gdupont]

Really glad we had this discussion -- I checked the C. lueddemanniana (originally potted in medium bark & perlite) and it has almost no live roots left

Repotted it in a fresh, chunky bark mix, hoping it puts out some new roots quickly. Any suggestions? Should I put a small strand of sphag underneath the newest pseudobulbs to add a little humidity there and encourage root growth?

Can't imagine the roots died from watering twice a week in the first two weeks...

[Roberta]

Originally Posted by gdupont

Should I put a small strand of sphag underneath the newest pseudobulbs to add a little humidity there and encourage root growth?

Can't imagine the roots died from watering twice a week in the first two weeks...

That level of root problems was there before you got the plant. Roots don't rot that fast. Don't add sphag... the surface of the bark will hold enough water for humidity, the air is what's important. The plant will draw on its older pseudobulbs for energy until those new roots (and attendant new growth) kick in. (Don't worry if those shrivel a bit.. with no roots it can't take up water, but those reserves of food and water will keep it going and support the new roots and new growth.)

[Leafmite]

Here is some useful information on the Cattleya:

Cattleya gaskelliana

I have always grown my Cattleyas in red lava rock/basket pots. I like not having to worry about the medium decaying and compacting. It is also nice because, if there is a very rainy summer, I just add extra Calcium and the Cattleya is fine, roots and all. This year, I added limestone to the lava rock and put the pots in bowls during the winter (orchids are under lights and I have low humidity). I watered well and let a little water in the bottom of the bowls. By day two, the water was gone. When the orchids go outside, they will not have the bowls.

Good luck![COLOR="Silver"]

---------- Post added at 03:21 AM ---------- Previous post was at 03:15 AM ----------

[Fairorchids]

Originally Posted by gdupont

Thanks so much, ghuylar and Roberta!

ghuylar – I'll be sure to avoid sphag! Good to know about the humidity vs watering point, I'll keep that in mind. And glad to hear the pot size looks right!

Roberta – thanks for all the advice! The basket option is interesting, I imagine that in low humidity that would require at least daily watering? I chatted with Wayne & Alice about the plant a bit when I purchased it, they mentioned it was kept in the cool greenhouse. I'll go for the bark!

For mature Cattleyas in home environment, I would suggest that you do not use 'large' bark. That will dry out too quickly.

I agree with previous poster that 40% relative humidity is adequate. For mix, I favor the one used by Waldor Orchids (2-3 parts bark, 1 part charcoal and 1 part coarse Perlite). The bark & charcoal should be nuggets ranging from about 3/8" up to 3/4" size. Any larger than that, and it becomes difficult to fill the pot in-between the roots (and again, it will dry out too fast).

I mix my own as I go along.

• I use above for plants going into 6" pots or larger.
• When potting smaller Catts going into 4" pots, I use 2 parts bark in the size recommended above + 1 part seedling size (1/8"-3/8").
• Finally, potting up small seedlings, I use 3" plastic pots with ventilation slits, and a mix that is about 1/2 chopped spaghnum + 1/2 seedling size bark/charcoal/perlite.

BTW, I use primarily clay pots for plants I want to keep, and plastic pots for plants I intend to sell.

[gdupont]

Thanks for the responses, everyone, I really appreciate it! Getting a bit overwhelmed though, trying to figure out which option is right for my environment.

Yesterday, after seeing the damage on the lueddemanniana, I pulled the gaskelliana out of what I had it potted in (large bark mix, first photos in the thread), and found that the mix was still pretty wet, 2+ days after watering, which made me think that isn't the right option (nudging me towards Roberta's suggestions, but more along the lines of Kim's). However, that was in a plastic pot, so perhaps a clay pot would be better? Trying to make sense of these differing opinions!

[Roberta]

Clay (terracotta) pots do dry out faster than plastic pots - and they are porous enough to "breathe" a bit. If a basket is impractical, that's the next best for letting roots dry out. Anything to get the wet-dry cycle that Catts (and other dominant epiphytes) need. Lots of ways to get there, under many conditions... just keep the objective in mind, then you can look at the best "how".

[isurus79]

Yep, clay makes a big difference in how quickly it dries out.