Pumice: where do I find it?

[Ray]

Nope. Always use coarse, with no additives. Cymbidium roots are pretty fat, so I think going with a finer mix could be an issue.

[Asian Cymbidium Empress]

I only use the traditional Japanese Cymbidium Mix that is composed of 3 kinds of pumices: hard kanuma, baked akadama, and satsuma. I buy them as a premixed bag in a premixed ration. Of course, all 3 grades (large, medium, and small). I only start growing Cymbidium goeringii after I was able to find them. Unfortunately, it is not available in North America (Us/Canada), so I flew to Japan to get them.

FYI: There are different qualities of the pumice and you only want to use the best one. The poor quality ones will break down very fast and the pot can be water logged.

[DirtyCoconuts]

forgive an ignorant question but why pumice over perlite?

[Roberta]

Originally Posted by DirtyCoconuts

forgive an ignorant question but why pumice over perlite?

Actually, a very good question!
Mixed in with other things, perlite is great for keeping the mix open without adding to weight. The bad thing about perlite, if it is the dominant part of a mix, is that it doesn't add to the weight. For instance, I use pumice instead of perlite in my mostly-inorganic mix for the Mediterranean terrestrials, so that the pots are heavy enough not to tip over in the slightest wind. Pumice behaves pretty much the same way as perlite. In most places it probably costs more and is less available, so I'd use it just where I need the extra weight.

[Asian Cymbidium Empress]

The Japanese and Korean have been using this pumice for a long time, why reinvent the wheels?
First to answer Roberta's questions about why pumice and not perlite. There are 3 different kinds of pumices in this mix. The pumices are called Kanuma, Akadama, and Satsuma. Each pumice has specific properties that will compliment each other, for example, Kanuma provides the stickiness to the mix, so the roots can adhere. Akadama can retains the most moisture out of the three. Satsuma has the poorest water retention but it provides the aeration. When the 3 pumices are mixed in a correct ratio, it will provide the correct pH, aeration for the roots, and the correct balance of the moisture for the roots.
Now to answer Dirty Coconuts' question. You can not buy this anywhere in US/Canada. I flew to Japan to get them.

[DirtyCoconuts]

Roberta, your responses are always so well expressed and informed and they so fully answer questions, you must have a background in either education or management/leadership

thanks!



to dovetail off the original question, could one simple add a weight (inside the pot, heavy rock) or outside the pot (wide base) and then use the perlite since the "correct" pumice seems so difficult to obtain?

i am fascinated by these plants and want to dip my toe in but i have to make sure i am willing to meet their needs as i am a pretty stubborn gardener

[Roberta]

DC, actually I'm just a retired geek. (Taught high school and middle school for a few years, but decided that I needed an easier job... like wrestling alligators. I have sooo much respect for teachers!) But thanks!

rePotme does carry those various specialized pumice forms (and other media that I don't even begin to know the characteristics of, most of my orchids do just fine in conventional mixes) - a bit spendy, but if you're looking for something specific, that's certainly a source. Sure, rocks for weight work... it's all about what you're trying to accomplish. Another characteristic of pumice (the generic kind) is that unlike perlite, it doesn't crush when you look at it the wrong way.

[Asian Cymbidium Empress]

Dirty Coconuts:
I didn't see that you are from Florida. Florida is too hot for Cymbidium goeringii I think. In the summer time, it likes hot and humid (Asian summers), but in the winter time (from mid Jan for at least 50 days, the temperature requirement is just above freezing (0C/32F). During this prolonged cold temperature treatment, my growing area never go above 11C (51F).

[Roberta]

DC, another question... are you looking for a mix for Cymbidiums in general, or the specialty Asian Cyms? Asian Cymbidium Empress is correct, Cym. goeringii would not be happy in south Florida. (Cym. ensifolium or sinense might be quite OK) But if you're looking at hybrid Cyms, no need to get that fancy. They do very well in small bark with #2 or #3 perlite, in your humid climate even medium bark might be better. For those, you'd want the ones that are bred for "warmth tolerance", not needing the fall cool-down to bloom. And there are an increasing number of those available.

[Asian Cymbidium Empress]

Hi Roberta:

I would like to point out your statement about the fall cooling down. I don't know where people get this idea, it's wrong for Cymbidium goeringii.

Cymbidium goeringii's flower buds are induced and set in the middle of the summer (in the midst of Asian Summers, at least in the 30C+/86F+ where I am dying from the heat (I lived in Taiwan in my childhood and I always avoid visit my mom in the summer June/July/August).

My point is this: setting/inducing the buds have nothing to do with the cool temperature in the fall. By September, October, it is already too late to set/induce the buds, you already past the window of opportunity.

You need the cool/cold temperature from late fall throughout the whole winter to hold the bud to make sure that it doesn't blast and the low temperature is required for proper flower developmet (agricultural term is called vernalization).

I hope this makes sense.