Rock Wool Medium

[Ray]

Originally Posted by The Peloric Orchid

I read that it's not recommended to use organic fertilizers with rockwool because it will grow algae. Do people that use organic additives (Kelpmax and Quantum) still use them after switching to rockwool and rockwool mixes?

Absolutely!

I don’t know where you’ve read that, but Organic/inorganic/shmishorganic. No matter the origin, nitrogen + water + light = algae.

[WaterWitchin]

I've recently been doing a lot of my repotting in shmishorganic. Seen some amazing results.

[Roberta]

Algae doesn't hurt the orchids.

[WaterWitchin]

Originally Posted by Roberta

Algae doesn't hurt the orchids.

Ahem, yes, a sensible moderator's response on the thread. I'm trying...

The best solution for not seeing algae growth in a pot, whether organic, inorganic, or schmishgamic, is to not use a clear pot. When I still grew in a bark medium a clear pot was still my choice, giving me a better view of what was going on beneath the surface. Algae would also grow on the bark in the pot. It just wasn't as noticeable because of the color contrast between bark and algae. I have a plant in tight sphagnum in a plastic basket right now (sent to me that way) and it's totally covered in a mix of algae and moss.

As Bill says... light+water=algae. Algae is irrelevant to the plant. It's just an aesthetic choice.

[Ray]

I will add that if algae buildup is extreme (which can lead to moss growth that can stifle airflow), you are probably overfeeding.

[camille1585]

I'm about to repot some Phrags and was thinking of doing a leca/rockwool mix. For those of you who did some experimenting back when this thread was active, how are those plants doing now?

[Tim P.]

Originally Posted by camille1585

I'm about to repot some Phrags and was thinking of doing a leca/rockwool mix. For those of you who did some experimenting back when this thread was active, how are those plants doing now?

Honestly, don’t use it. It led to a lot of heartache. I used it exclusively on my phrags, and it killed many a prized phrag due to erwina to the point I have completely started over and currently only have two in my collection. It just stays too wet if you use saucer culture. I recently went up to Orchids Limited and they too are transitioning all their phrags out of rockwool, which is quite telling. One of their reasons was it breaks down too quickly.

What am I using? Good old orchiata, with chunky pearlite. 1/2-3/4 inch chunks. It’s a chunky mix that would work with cattleyas, but it’s working better so far.

I still mourn the loss of some of those phrags

[WaterWitchin]

I started off around the time this thread began by transferring about ten phrags to the leca/rwool cubes. By end of year had all phrags and paphs in the same medium mixture. Within next year redid a bunch of other genus to the same. By now, I'm not sure if I have anything that isn't the same mix. So obviously had good results or wouldn't still be doing it.

All are in semi-hydro, so I can't speak to Bill's method of regular pot in a tray, but I see them both as performing about the same way. It increased by a few days the amount of time span before re`watering, and improved the dry line issues during lower humidity months in the winter. I think Bill mixes his leca and rockwool, or at least used to. I do it in layers for the most part.

The only negative issue for me is I refuse to wear gloves and sometimes handling the rockwool when dry makes my hands itch.

[Dalachin]

All of my Phragmipedium have been in leca and rock wool with a water reservoir for over a year and thriving. I added rockwool to the leca when I repotted some paphs recently, but it is too early to say if it will be an improvement over pure leca.

[Ray]

Mine are doing well, too.

I think what it comes down to is how much time do you have to water, and do you like doing so? If the answer is "Yes", the 100% LECA is probably the better choice. If "No", then the mix is advantageous.

Keep in mind that going from LECA to a blend is still changing the root environment, so time your repots accordingly.

There is a guy in SC who grows them in rockwool cubes with about 5%-10% horticultural perlite, which provides air spaces between the particles, but the container is still mostly rockwool. Lots of awards, but he took some time to convert them and learn how to grow them that way.