Lava Rock & Lecca

[SADE2020]

I have some doubts, maybe someone would be so kind to answer if they know. (@Ray I am sure you have some inputs :-))

Lava Rock and Lecca during cold months maintain the same temperature?

I have done a Lava Rock test in winter with 5v plants and the truth is that the humidity retention is very good compared to Lecca (not in SH).

What happens if I combine the two for a weight and stability issue and in Winter I DON'T do SH and in Summer YES, with the same setup?

THANKS!!!!

[Ray]

As a medium in traditional culture, I doubt there will be much issue with temperature. In S/H culture, I would guess there would be more of an issue.

My guess at the scenario: a little bit of evaporating water has a little bit of cooling effect. Once the water content of the medium decreases, the cooling effect does, as well.

In semi-hydroponics, the water content in the medium doesn't decrease, so the evaporative cooling effect continues, making the medium cooler. There is a moderating effect, of course, as the cooler temperature slows evaporation.

[SADE2020]

Thank you, Ray. So helpful as always.

I think I am going to for that setup with some repot I have to do.

[OrchidLoverCA]

Originally Posted by Ray

As a medium in traditional culture, I doubt there will be much issue with temperature. In S/H culture, I would guess there would be more of an issue.

I see in your answer you mention traditional culture done in Leca/Lava.
I am relatively new to SH, and some of my Phals are struggling a bit during the winter in their SH setup. I have lost some roots due to the media staying too wet all the time.
Should I assume from your answer that I could do traditional culture during the winter while maintaining the same media in order to keep the roots drier? How is it done, please?

[Ray]

The loss of roots probably wasn’t due to them being too wet. If the roots grew in the moist LECA, then they are perfectly adapted to being in the wet conditions.

Instead, I’d bet that evaporative cooling due to lower humidity coupled with lowered winter temperatures resulted in the roots being too cold - an extremely bad combo when wet.

[Leafmite]

I would agree with Ray. Maybe you could try putting your S/H orchids on a heat mat until the roots have adjusted.

I use lava rock but not for S/H...just as a medium. I have not had any trouble with it in the winter. It seems to work better for me in cooler temperatures than any of the other mediums...probably because it allows maximum air flow to the roots.

[tmoney]

well i know you asked ray, but figured since we have some similar issues with phals in s/h that i would chime in. we simply drain the reservoir really well with our phals. especially this winter. so, they are in leca and s/h but pretty much just grown with a dry reservoir. our 3 phals treated this way made it fine this winter...

[estación seca]

Ray has pointed out roots grow adapted to the current conditions. Semihydroponic-adapted roots would likely struggle in standard culture, and vice versa. Switching conditions with the seasons might lead to regular root loss.

Staying wet is not a problem for Phal roots if temperatures are correct and they have plenty of air. They are wet most of the growing season in habitat.

[MateoinLosAngeles]

S/H is the only setup that has never resulted in any issues for me. Plants seem to adapt and thrive very quickly provided that:
- You bought LECA that is fairly uniform and good quality (e.g. not colorful LECA that is coated and has diminished wicking).
- You prepared the LECA well.
- You repotted at an appropriate time (Although I've "rescued" plants by moving them from whatever media into S/H in the depth of Winter without issues).
- You water frequently and abundantly (flooding the pot) with pure water (RO, rain...) and feed lightly at every watering.
- Your temperatures are right.

I keep all my Phals on heat mats and some of them have little plastic discs on top to slow evaporation down.

[OrchidLoverCA]

Many thanks to all who replied to my comment!
I really appreciate the useful info and help.

To be more specific, towards the end of last summer I decided to transfer most of my orchids from bark to SH. At the time I had mostly Phals in bark. They were very large vigorous plants and I have been very successful with them for several years.

The reason why I wanted to transition to soilless media was that I needed to get rid of a huge infestation of fungus gnats that had been plaguing all my indoor plants despite the many 'remedies' I have been trying over the years.

I grow all my orchids indoor on a windowsill facing south-west, in Southern CA, so my temperatures are fine for most orchids even in winter (57-70F in winter and 75-90F in summer). Humidity around 50% on rainy days, 30% or less the rest of the time.

So, at the time I transferred my Phals to SH they had huge active root systems adapted for bark (large chunks, lots of air gaps, dry-wet cycles as usual).

After several months in Leca, though, some of the Phals have grown new roots into the Leca, but have also lost many of the old roots. The lost roots looked as if they couldn't adapt to the highly moist media that is Leca in SH. They kind of got squishy and rot. One Phal lost all of the roots. Another almost all, and it is now down to only one root left. The majority of my other Phals kind of adapted, have grown new flower spikes and many are in bloom right now. And yet, the leaves are not as good as they used to be. I know them, and I cannot say that they are very happy. They are just 'ok', but not thriving as they used to, if you know what I mean...

As for winter temperatures. Before, when they were in bark, they have been overwintering without problem, with no heating mats. After I transferred them to Leca, though, I placed them all on heat mats, cause I know that Leca SH has a cooling effect and is much more wet than bark, and I wanted to help them with the transition.

I also have many Paphiopedilums and Oncidium Alliance hybrids in SH, and they all have responded wonderfully, even Miltoniopsis. Only the Phals are kind of struggling.

So, when I read that one could grow in Leca but in a traditional way, instead of SH, I thought that maybe I should try to keep my media drier (much dryer in fact) instead of keeping the reservoir filled with water at all times, cause that's what's killing the roots, right now, I think. Too much moisture compared to what the roots were accustomed to in bark.

If you grow Vandas, you'll know what I mean, when I say that my Phals now look like when you try to grow a Vanda in a pot filled with media instead of bare rooted.

The thing is, I'd rather not go back to bark with my Phals, if I can help it. First because orchids don't like changing media again and again. Second, I don't want to go back to the fungus gnats problem. But I don't want to see all of my Phals slowly decline either....

What do you guys think?