I've been hearing about these for sometime now. Was hoping that members here can share their experences with this media. Want to hear both the good and the bad. Please be sure to include your growing conditions and locations. Such things as, can you pot up without removing the cubes? Does the roots grow threw the cubes. Can the cubes be reused. Do they hold salts? What group of orchids are you using it for? How often does it need to be changed, once a year? How often do they need to be watered in your conditions? Do you need to still sit them in an inch or two of water for phrags?
Thanks to all members that take the time to inform the rest of the members on this forum.
Jerry Fischer at Orchids,Ltd. says phrags and miltoniopsis love the grow cubes. His mix is 65% cubes, 25% perlite, 10% charcoal. I use 55/35/10 and next mix will add oyster shell. He also uses bark for phrags, but not moss, as he says it tends to be too acidic. I now grow phrags and miltoniopsis in my main level of my home high 74 day temps with air circulation, 45-50% humidity, very bright East windows, because my grow room (under LED lights) was too warm for them to be happy at 84 degrees in summer.
I water when the cubes on the surface just start to dry (phrags). The cubes, according to the manufacturer are 50% hydrophilic and 50% hydrophobic, so technically hold ½ air. Jerry says their shape causes good air spaces in the mix, especially with the perlite. 7 days is a little long for me to go, but my phrags are in small pots being rehabilitated, right now. I feel as though they stay wet, as the cubes do not dry out visibly below the surface, but there is good root growth with them (I use clear plastic).
If you search a previous thread I started in April/May "Advice, please re Phrags", if my memory serves me, PeteM posted pics of a small Fritz Schomberg he bought at the Paph Forum the same day I bought one. These were not well rooted. I downsized mine which was in bark, to bark, he downsized his experimenting with grow cubes mix. His results after just a few months were remarkable per his photo--I almost lost mine!! I've since repotted in grow cubes and moved it to cooler temps.
Re repotting without removing the cubes. Yes, according to Jeff Morris of Charlottesville Orchid Soc. who exhibits many CCM awarded specimen phrags (many of the same plants get CCMs every year he exhibits) in large (2 gal and larger containers) because the cubes never break down, he just removes the pot, puts it in a bigger pot, adds cubes around the outside/bottom and (in large pots) adds a couple of inches of bark on top to keep algae from growing. His theory is phrags don't like their roots disturbed, so they are very happy with this system and his plants certainly are a testimony to that!
Re accumulating salts, yes, so every 3-4 weeks flush with clean water, no fertilizer (per Jerry). So the last week of the month, they get clean water. I do not sit my phrags in an inch or two of water. Some do, but it has never worked for me (I killed my first Jason Fischer doing that when I went away for 4 days, it was still moist when I returned, however, declined rapidly after that.) I've not noticed my roots growing through the cubes, but I see a lot on the outside of the mix through my clear pots, but I don't pick apart the mix when repotting, so they might. Hope this helps. Look up the thread, a lot of comments there will be helpful and Pete M's photos speak for themselves!