Gordon, rock wool cubes

Slippertalk Orchid Forum

Help Support Slippertalk Orchid Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
Joined
Jan 19, 2020
Messages
252
Reaction score
202
Not a novice. I havebeen growing orchids over 20 years. But, I am thinking about trying something new with my Phrags. I would like to starting to add Grodon to my media mix. I once read on here that Grodon need a prep soaking before using? Any suggestions?
George
 
Not a novice. I havebeen growing orchids over 20 years. But, I am thinking about trying something new with my Phrags. I would like to starting to add Grodon to my media mix. I once read on here that Grodon need a prep soaking before using? Any suggestions?
George
I grew my Phrags in a mixture that was about 75% LECA and 25% Grodan cubes by volume and growth was fine. I did not like the blue/green bacteria that grew easily on the rock wool on the top surface or on the side walls in semi-translucent pots. I could have switched to opaque pots and had only LECA on the top layer. My growth and flowering were good, but the rock wool cubes compact over time and can start to become an air barrier. There are various posts on Slippertalk from people talking about abandoning pure rock wool for orchids, including Phrags, and this includes some commercial growers. I think that adding a little can be fine.
 
I use the GrodAn Growcubes for my Paphs and Phals since about 1,5year. I habe really good success with it. Before using you have to soak them, best in rainwater. During the use never let it become bonedry. Sometimes there is black algae growing on top, but this is replaced by nice moss after few weeks.
 
I just add them to my mix dry. I never measure, but about 20-25%. I always pre-soak my mix for at least a day before using it. Really wet, I have to drain water out of the mix tub before I pot.

Only been adding them for a year or two, haven't noticed any adverse effects at that mix rate. 100% rockwool cubes never seemed to work as well as I hoped, so I am just using them as a moisture retentive component in my usual bark mix. I may or may not continue to use them after my (vast) supply runs out.
 
Just to add my experiences with phrags and rockwool. 100% rockwool cubes worked well in small pots, say up to four inch ones. In pots above that size, the rockwool compacted over time. Root growth was poor deep in the pot, they were all on top or just under the surface.
 
I grew my Phrags in a mixture that was about 75% LECA and 25% Grodan cubes by volume and growth was fine. I did not like the blue/green bacteria that grew easily on the rock wool on the top surface or on the side walls in semi-translucent pots. I could have switched to opaque pots and had only LECA on the top layer. My growth and flowering were good, but the rock wool cubes compact over time and can start to become an air barrier. There are various posts on Slippertalk from people talking about abandoning pure rock wool for orchids, including Phrags, and this includes some commercial growers. I think that adding a little can be fine.
No, I am not think pure rock wool I knowit compacts and would root root!
 
I have switched all Phrags to a near 50/50 croutons/perlite. Very happy with the results. Do make sure that you not only presoak, but also pour off the water and lightly squeeze out the water. Raw, they are 8+ pH. For me usually two rinses does the trick but my tap is super soft.
 
My phrag kovachii loves them mixed in with small orchiata bark, pumice (to keep the air circulation because the grow cubes keep pretty saturated), gia flower fertilizer and glacier dust. The only problem that i do have with them is that it is noticeable that salt collects in them, because when the top ones dry it is visible. I just soak them in a large bucket of water and that draws a lot of it out. This works for me but people hear will probably attack this method so take what I say with a grain of salt or people will start an all out war 🙄🙄🙄. Also don't be afraid to do a little at a time like 25% then if it drys out add more or vis versa.
 
The mineral buildup isn’t solely due to the cubes. Your growing conditions play a significant role, as well.

The salts come from your applied solutions as well as the soluble ingredients in your potting mix. They precipitate when the solvent (water) evaporates. A particle that can hold more solution will also hold more dissolved, making the the precipitation greater when the water evaporates.

Slow the evaporation, slow the buildup.
 
I believe the larger size are called Grow-Chunks.
We are moving all our Phrags into a mixture of Grodan cubes, diatomite, leca, and coarse perlite. See photo. The instructions say to mix plant food in water. For hard water areas add lemon juice. Then, soak the Grow-cubes in the solution.
 

Attachments

  • 20231207_202725.jpg
    20231207_202725.jpg
    1.9 MB · Views: 0
I believe the larger size are called Grow-Chunks.
We are moving all our Phrags into a mixture of Grodan cubes, diatomite, leca, and coarse perlite. See photo. The instructions say to mix plant food in water. For hard water areas add lemon juice. Then, soak the Grow-cubes in the solution.
That seems like a nice mix!!! Does this also work for smaller plants or ones with smaller root system?
 
Thanks for the conversation. This is related to my recent question about growing Paphs in an inorganic medium. Seems that rockwool has many drawbacks
. I’m wondering also how the container influences root growth when combined it’s the medium. I have many plants in semi hydro, and perhaps I should stick with that, but I’d like to find a component to add to leca that retains more moisture but without the compacting and algae that seem to come with rockwool
 
I believe the larger size are called Grow-Chunks.
We are moving all our Phrags into a mixture of Grodan cubes, diatomite, leca, and coarse perlite. See photo. The instructions say to mix plant food in water. For hard water areas add lemon juice. Then, soak the Grow-cubes in the solution.
Sort of looks like my mix. Works great for my Phrags.
 

Attachments

  • DSC_0930.JPG
    5.3 MB · Views: 0
  • DSC_1118.JPG
    5.7 MB · Views: 0
  • DSC_1122.JPG
    5.3 MB · Views: 0
I’m using the mix like Eric and Ray for most of my kovachii hybrids in an attempt to keep the roots cooler. I’m not sure there is enough airflow tho. I’m getting good root growth but slow otherwise…most of my besseae hybrids in small bark/charcoal/perlite with a little rockwool thrown in seem about the same. Experiment continues….
 

Latest posts

Back
Top