# Grodan/Perlite growing media . . .



## LWP (Mar 8, 2021)

What experiences have members had with the above mix. I have seen it recommended for Phrags . . . do Paphs do well in it also.

tks, . . .


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## NYEric (Mar 8, 2021)

Just those 2 media!? The closest I have heard is the mix that Orchids Limited was growing Pk in, grodan, perlite and diatomite.


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## Ray (Mar 8, 2021)

My paphs and phrags - under my growing conditions - seem to do better in a coarser version, 50/50 Grodan 1cm cubes and LECA, than they do in straight cubes. I know it’s not the mix you asked about, but I think the amount of open air is similar with straight cubes and cubes+perlite.


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## ScientistKen (Mar 8, 2021)

My experience has been similar to Ray's. Adding something to open it up helps. I use either perlite or LECA or often both. If using perlite only, use a very coarse version. Most of my rockwool cube experience is with phrags. Paphs have been kind of hit and miss and even when they do great, the roots haven't looked so great when I go to repot. The tops can fool you. You might have a different experience depending on your watering approach, humidity, etc. I haven't tried the cubes on paphs larger than compot size.


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## Anca86 (Mar 9, 2021)

I am using as Ray says 50/50 grodan LECA. I have 2 paphs and most of my phrags in this mix. The Paph micranthum I put in LECA/grodan is growing a new fan so I would say it likes the mix.


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## sergeharvey (Mar 9, 2021)

I've been using 3 parts minicubes of Grodan with 1 part coarse perlite for the 'wetty' Phrags - bessae, schlimmii and kavachii primary hybrids. They grow like mad. Water every 3 days or so at a water pH of about 6.8, and I fertilize 3 times out of four with a variety of fertilisers at about 100ppm N. Don't use clear pots because it gets rather quite slimy with algae though it doesn't seem to hurt the Phrags - so far.


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## NYEric (Mar 9, 2021)

Hi Canada!


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## Kyle (Mar 9, 2021)

NYEric said:


> The closest I have heard is the mix that Orchids Limited was growing Pk in, grodan, perlite and diatomite.



Do you know if they are still using that? I experimented with straight Grodan a few years ago and had favorable results.


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## PeteM (Mar 9, 2021)

I’m still slowly switching the collection of phrags over to grodan mini cubes and 15-20% perlite with styrofoam peanuts in the bottom. So far kovachii, and it’s hybrids I grow are performing well. I’m also experimenting with net pots both large and small. Also enclosing the media in a solid exterior pot or using a rand aircone pot. So far I think the results are positive. I am seeing stronger growth with the enclosed pots in the current winter / spring conditions, the enclosed pots have more active roots and less dried tips. I’m interested in the exposed net pots for summer, to increase airflow and evaporation / cooling the roots in the warmer summer months. On the other hand.. m Some pictures included. I seem to be really good at growing moss.. moss might need a hair cut soon.


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## cpmaniac (Mar 10, 2021)

I have been using a similar mix to what Pete M is using, with good results for "short-petaled" wet growers. I bought a sack of LECA recently, and plan on mixing it roughly 1:1 with cubes, and using for the species and hybrids that I have in bark mixes.


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## richgarrison (Mar 10, 2021)

love that moss... guessing these are under lights... what's your watering regime?


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## PeteM (Mar 10, 2021)

richgarrison said:


> love that moss... guessing these are under lights... what's your watering regime?


Hi Rich, yes this table is under two COB LED fixtures (1800 Watt X6 Cob Led Grow Light Full Spectrum Led Plant Light with Daisy Chain, Temperature and Humidity Monitor, Hanging Hook, Adjustable Rope Amazon.com) maybe this link will work. I hand pump spray with diluted fert (25-50ppm) then water with a hose of RO every evening about an 1.5-2 hours before lights out.

FYI.. I’m not recommending these lights to others, it’s was the best value at the time of purchase about Two years ago. Tech has improved rapidly since then but I still get good results with these. Hope to swap there out with a passive ‘fan less’ system when these fail.


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## Anca86 (Mar 10, 2021)

PeteM said:


> Hi Rich, yes this table is under two COB LED fixtures (1800 Watt X6 Cob Led Grow Light Full Spectrum Led Plant Light with Daisy Chain, Temperature and Humidity Monitor, Hanging Hook, Adjustable Rope Amazon.com) maybe this link will work. I hand pump spray with diluted fert (25-50ppm) then water with a hose of RO every evening about an 1.5-2 hours before lights out.


Why in the evening?Everywhere is written to water in the morning. By the way, your orchids are great and I love the moss.


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## PeteM (Mar 10, 2021)

Anca86 said:


> Why in the evening?Everywhere is written to water in the morning. By the way, your orchids are great and I love the moss.



From what I understand.. like everything else that live in these unique tropical montane environments, it is beneficial for the system to experience a drop in temp at night but also a spike in humidity. Most orchids utilize a CAM system, (Crassulacean acid metabolism) and if there is drop in humidity at night I believe there will be more water loss when the stomata open at night. Francisco Mirenda mentioned this in one of his online talks..either the cattleya forum or AOS webinar.. his example was fog rolling in at night for a region. Interestingly, since researching chameleon husbandry for a Montane species (a new covid hobby), the common practice is to ‘fog’ the cage at night and try to get the spike of humidity in order to keep the chameleon well hydrated.

So, I water my vandas, phrags and a few mounted plants in the evenings to help cool down the phrag roots and help generate that night time spike in humidity for the grow room and the chameleon that lives in a cage in there.


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## Anca86 (Mar 10, 2021)

PeteM said:


> From what I understand.. like everything else that live in these unique tropical montane environments, it is beneficial for the system to experience a drop in temp at night but also a spike in humidity. Most orchids utilize a CAM system, (Crassulacean acid metabolism) and if there is drop in humidity at night I believe there will be more water loss when the stomata open at night. Francisco Mirenda mentioned this in one of his online talks..either the cattleya forum or AOS webinar.. his example was fog rolling in at night for a region. Interestingly, since researching chameleon husbandry for a Montane species (a new covid hobby), the common practice is to ‘fog’ the cage at night and try to get the spike of humidity in order to keep the chameleon well hydrated.
> 
> So, I water my vandas, phrags and a few mounted plants in the evenings to help cool down the phrag roots and help generate that night time spike in humidity for the grow room and the chameleon that lives in a cage in there.


Very interesting. Thanks for the info.


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## cnycharles (Mar 11, 2021)

I had seen reports from some a few years back where they showed their mounted plants benefited most from watering or misting before nightfall


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## PeteM (Mar 11, 2021)

Anca86 said:


> Very interesting. Thanks for the info.


I just wanted to add for others that you must have fantastic air movement for watering in the evenings, especially in the winter. My grow room does not drop below 60 at night. But on occasion I will add too much water at the wrong time, even with the lighter hand pump sprayer. I have lost a few cattleya seedling leads that have rotted with sitting water in the leaf. It's a 'routine' , but one that you have to constantly be mindful of and question yourself about temps, timing for drying out a bit and also physically getting the water on the roots and not the crown of the plant.


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## richgarrison (Mar 11, 2021)

" Most orchids utilize a CAM system, (Crassulacean acid metabolism) ..."

Carlos Fighetti has also presented those concepts as reasoning for watering Phals at night... especially since (according to Carlos) Phals in situ are typically watered by mother nature right before they turn in for the night... In Carlos talk he contrasted the C3/C4 photosynthetic processes from CAM. With examples of orchids that were not CAM... He gave that talk back at the IPA meeting in Phila 2018 (i think). This article has some readable information..


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## PeteM (Mar 11, 2021)

richgarrison said:


> " Most orchids utilize a CAM system, (Crassulacean acid metabolism) ..."
> 
> Carlos Fighetti has also presented those concepts as reasoning for watering Phals at night... especially since (according to Carlos) Phals in situ are typically watered by mother nature right before they turn in for the night... In Carlos talk he contrasted the C3/C4 photosynthetic processes from CAM. With examples of orchids that were not CAM... He gave that talk back at the IPA meeting in Phila 2018 (i think). This article has some readable information..



'Compared with terrestrial orchids, epiphytic CAM orchids usually grow under conditions where the volume of substrates is limited because of the scouring action of frequent rainfall.Furthermore, because those regions have relatively high temperatures, the potential for daytime evaporation is elevated. Stomatal closure is a very efficient strategy for minimizing water losses during the daytime. At night, the relative air humidity is very high there, which may lead to a low rate of evaporation and prompts those orchids to open the stomata for CO2uptake. Photosynthetic carbon gain is optimized in some orchids that are facultative CAM plants but also induces C3photosynthesis under well-watered conditions (Kerbauy et al., 2012). For example, Dendrobium officinale exhibits a typical CAM pattern when the content of substrate water is diminished (Zhang et al., 2014), but those plants reveal a concomitance of C3and CAM patterns when re-watered. A shorter light dark cycle leads to a C3pattern alone. Consequently, substrate moisture and the light dark cycle are inducible factors for switching between C3and CAM patterns in that species (Zhanget al., 2014). Thus, the CAM pathway is an important strategy by which many epiphytic orchids prevent water loss and acclimate to fluctuation in water availability.'

Thanks for this article. I thought the section on nutrients was also very informative.


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## Ray (Mar 11, 2021)

I agree that the nutrient section was particularly interesting.

Two of the "pluses" of Quantum-Total are the nitrogen-fixing and photosynthesizing microbes in the formulation, but compared to Inocucor, there are no mycorrhizal fungi. They used _Saccharomyces cerevisiae_ - brewers yeast - so it ought to be easy enough to add. That might be upcoming on the experiment list...


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