Rock Wool Medium

[JScott]

This is only tangentially related to the topic, as I'm not using rockwool for SH, but I had a couple Phals and a couple Catts that I had neglected to repot in a timely manner, and they lost very nearly all of the roots. I was about to throw them away, but then I thought what the heck, let's experiment. I planted them in pure rockwool to see if that would encourage root growth and help revive them.

The results have been good. The Phals are doing great in straight rockwool. I think I'll leave them like they are indefinitely and see how they do, but they're good so far. They grew new roots, and the floppy leaves firmed back up, and new leaves are growing.

As far as the two Catts go, I don't feel like growing them in rockwool permanently would be the best idea (just a guess, I might be wrong), but like the Phals, they put out new roots (new roots on mature growths which should have been past the rooting phase, I might add), and then new growths. When the new growths started to root, I potted them back into a bark mix, and they are doing great, so based on my limited experience, it seems like rockwool may be useful for helping to recover plants with severely compromised root systems.

I had the rockwool on hand because in Milton Carpenter's article about his warm blooming Cym hybridizing program, he mentioned that he was growing Cyms in pure rockwool with excellent results, so I decided to try it, and I potted one of my Cyms in pure rockwool. It hasn't been in there long enough for me to really tell what the results are going to be, but so far there are no negative results. The plant is growing happily so far, so I'm optimistic, and I'm interested to see how the one in rockwool compares over time to the ones potted in organic media.

[DirtyCoconuts]

Very interesting

I wonder if it is the incredible humidity (stays wet but is porous) or maybe the fine texture that is so encouraging to root. Catts rooting out of phase is worth noting as an indicator of something.

Thanks for sharing.

[JScott]

Originally Posted by DirtyCoconuts

Very interesting

I wonder if it is the incredible humidity (stays wet but is porous) or maybe the fine texture that is so encouraging to root. Catts rooting out of phase is worth noting as an indicator of something.

Thanks for sharing.

I thought so too. I was optimistic about the Phals. I thought they had a chance. I was very surprised it had that effect on the Catts.

[Ray]

A little bit of data from my experiment:

I had 3 identical 3.5" Square pots I had acquired from Chula orchids



I filled one with Grodan (1cm) mini cubes, one with a 50/50 mix of that and LECA (particles approximately the same size), and later, one with LECA.

They were weighed dry, then I ran water through them from the top, saturating them totally. I waited 15 minutes and repeated that. I waited another 30 minutes for them to drain, then that gave me the initial (t=0) weight.

As a point of reference, the dry weight of the rock wool cubes was 44g and they held 228g of water. The Mix weighed 142g and held 150g water, and the straight LECA weighed 272g and held 26g water. (Note: It is obvious the LECA was not saturated, as prior experiments showed that absorption to be about 20%, not closer to 10%, but I threw that test in there to see how it would fare with "traditional" culture.)

The pots were in my packing room in my garage. Over the time I tested (4 days), the temperature in there ranged from 75° to 81°F, and the RH was fairly steady at 60%-67%.

I weighed the pots at random times, ending about 1 pm Monday 10/26:

[DirtyCoconuts]

Wow. So iniatial data suggests that the mix is the way to go. Almost the same retention on the curve

[Mr.Fakename]

I'm thankful the world has some people like Ray, so the rest of us can just wait for the results and enjoy better plants!

[Ray]

They both seem to perform similarly. One thing for sure, the mix weighs more than just cubes, so it might be a better choice for taller-growing plants.

I have transferred all of my phals out of sphagnum into the cubes, and am still experimenting with slippers.

Here's what they look like in the pot, wet and a light bit compressed. Still plenty of air space in both.

[vegetalmatter]

Originally Posted by Ray

Over the time I tested (4 days), the temperature in there ranged from 75° to 81°F

I'm interested in whether or not there is significant difference in evaporative cooling when comparing LECA vs rockwool vs LECA+RW

Am I right in thinking that better water retention = less evaporation = less evaporative cooling?

[Ray]

Originally Posted by vegetalmatter

I'm interested in whether or not there is significant difference in evaporative cooling when comparing LECA vs rockwool vs LECA+RW

Am I right in thinking that better water retention = less evaporation = less evaporative cooling?

That is my thought, as well.

I suppose I could stick a thermometer probe into the middle of the pots of media to check, but it's probably not significant at the moment, with our humidity...

[estación seca]

The evaporative cooling will be directly proportional to the loss of weight, since the cooling is directly proportional to the evaporation of the water.