Scoria/lavarock as a substrate

[Ray]

Originally Posted by KingKong

one disadvantage with leca is it dries out too much at the surface so needs to be covered by another media like moss or gravel.

I'm going to quibble with that a bit.

All media have inherent wicking rates, but the evaporation rates depend upon a variety of factors, from shape and packing density of the medium, to temperature, humidity, air movement and light levels.

In my greenhouse in PA, LECA stayed wet, clear to the top, and I never had a need to cover it with something to retain moisture. Growing on my deck here in NC, the same is true, but when I bring the plants in for the winter, it is drier, but I just water more frequently.

[farley101]

Ray, I've got one plant that I'm growing in leca that I have consistently had issues keeping the top inch from drying out. It's in a very large pot but I really didn't do much in the way of sorting by size of leca so I'd guess there are some inefficiencies of moisture transport due to that.

From what you mentioned above it seems I should water more? I've tried other ways to keep the top layer damp but nothing has been too effective. I try to water at least twice a week, should I try every other day or so? Thanks!

[KingKong]

you heard Ray Farley, if he says it is so then you are imagining your issue - it's in your head because it is not so

But in case you want a placebo pill to rectify your imaginary issue I would suggest you use a diffferent substrate as the top layer. For some plants it doesn't matter too much that the top layer dries out but with orchids that have thinner roots it seems to matter more.

Something that does not have the dessicating effect dry leca has (so pretty much any other media you prefer apart from seramis, that is even more dessicating), but still covers the roots from air drying as much.

In tall pots and depending on ones watering method this will all vary how much moisture reaches the top layer.

Like Ray points out his climate made a big difference too.

I am also not a fan of semi hydro, with semi swamp conditions. Everyone's situation is different - it does seem to be known by now that the top layer drying can be an issue but that would mean Ray would have to admit his semi hydro has flaws which it hasn't of course

[Ray]

Originally Posted by KingKong

you heard Ray Farley, if he says it is so then you are imagining your issue - it's in your head because it is not so

But in case you want a placebo pill to rectify your imaginary issue I would suggest you use a diffferent substrate as the top layer. For some plants it doesn't matter too much that the top layer dries out but with orchids that have thinner roots it seems to matter more.

Something that does not have the dessicating effect dry leca has (so pretty much any other media you prefer apart from seramis, that is even more dessicating), but still covers the roots from air drying as much.

In tall pots and depending on ones watering method this will all vary how much moisture reaches the top layer.

Like Ray points out his climate made a big difference too.

I am also not a fan of semi hydro, with semi swamp conditions. Everyone's situation is different - it does seem to be known by now that the top layer drying can be an issue but that would mean Ray would have to admit his semi hydro has flaws which it hasn't of course .

Is there a reason you have to be an insulting ass, Swimmy?

If you had read - and understood - my last post, I was not disagreeing about the dry top layer of LECA potentially being a problem, I was explaining why that can happen and that it can happen with any medium, but to different degrees. I made that explanation to correct your overly-broad and ignorant comment that I quoted.

I grow my phalaenopsis in straight sphagnum and that happens with that too, in the winter, when they're indoors.

I have never claimed S/H culture is perfect for everyone. I don't find it is perfect for all my plants either, and the mix of plants it is good for has changed since my environment changed.

Farley - There are any number of ways to remedy the "dry top" situation, each addressing the evaporation rate. I water more often because it's easy. Others mist the surface. Still others place some sort of barrier layer on the top to slow the evaporation. Some folks who grow in semi-hydro culture place the drainage holes higher in the pot sidewall so the reservoir-to-top distance is reduced. Ideally, you would adjust your growing conditions by increasing the humidity or decreasing the air flow, as that would likely be better overall for the orchids, but if you cannot do that, there are other alternatives.

[WaterWitchin]

I find the same thing in summer vs winter growing. My summers are very humid, plants outside, rarely does the top dry. Winters, in the BatCave, can't keep the humidity as high, top layer dries more rapidly.

For the orchids where it matters, I put stones that don't wick on top of the LECA. For others, I just water as usual and don't worry about the top being dry. Examples: Paph and Phrag, get pebbles. Anything that has active root growth (not many) get pebbles. Ones where humidity matters a LOT, get pebbles. The rest, nothing different.

Over time, one learns which need the assist and which don't. For me, in my climate and under my care, it works best for me. For me, I never grew as well in bark medium. I think that's likely more my choice in how I care for plants, rather than the actual medium involved.

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PS And I'm still waiting to see how it works for me in a greenhouse.

[DirtyCoconuts]

i am using a LOT of the SH techniques in my growing now and almost all of them are a slightly different take to a radical change that the SH fans might not even say is SH at all...but the concepts are similar but i am adapting it to a semi-swamp climate as well.

find what works for you and tinker to see if i can be improved

[WaterWitchin]

Originally Posted by farley101

Ray, I've got one plant that I'm growing in leca that I have consistently had issues keeping the top inch from drying out. It's in a very large pot but I really didn't do much in the way of sorting by size of leca so I'd guess there are some inefficiencies of moisture transport due to that.

From what you mentioned above it seems I should water more? I've tried other ways to keep the top layer damp but nothing has been too effective. I try to water at least twice a week, should I try every other day or so? Thanks!

And a PS or two Farley101... A "very large" pot does tend to have more dry line issues. More surface area. I don't think sorting LECA has much to do with it. I've been known to say if I start sorting LECA, just go ahead and get my padded room ready...or other words to that effect.

Use a deeper reservoir, put a layer of stones or marbles, or flat pieces of shale, etc, on top. The top layer being dry won't matter much unless it's trying to push new roots down, or because the plant is drinking that much water. I have a Cymb in a kitchen wastebasket with a five inch reservoir, and top layer is always drying (a lot of exposed LECA). But it also can drink that reservoir almost dry in a week's time.

[farley101]

Thanks (most) everyone for the replies! Camille, I apologize for hijacking your thread a bit. 😑

FWIW I am experimenting with lava rock for growing some juvenile cattleyas. They came in sphag and the new roots were burning off when they hit the top of the medium so I decided that something else should be tried. Also, they were $3 a piece so cheap enough to experiment with. They seem to be doing pretty well, I water ever other day or so and there are new roots making their way into the rock. It's pretty interesting to see with as seemingly sharp the rocks are!

Ray, I've tried a few different ways to combat the dry top - plastic barriers but the plant is so irregular that didn't help much and spraying the top, not great when I travel fairly often. It's a large Sharry Baby that I hacked 90% of the roots off last fall, it's in a 6"x8" glass cylinder and just starting to put out some decent roots and 2 new growths. Of course we got our first 90+ degree day today and that tested the resolve of all the plants I had outdoors that were not used to that yet! Luckily they are all in the shade after 1 or so so they didn't get cooked too bad.

WW, I'll look into adding some non-evaporative rocks to the top layer. Seems like the best option currently. I am hoping once it gets some roots in the pot I can do some adjustments since it ended up a little weird due to the no healthy root issue. 😆

And DC - I have the same urge to tinker and try to experiment with what I'm doing to try and make things work better or easier if possible! I like that I can fuss over my plants and water a lot if I want with inorganic medium, I just have to make sure it'll work in the crap winter when everything has to be indoors! You've got it made down there!

[DirtyCoconuts]

No doubt, my friend.

You northern folk who actually have to work at keeping these plants are heroes. No joke. I am always saying it and I’ll keep saying it. I am not good at growing plants. I am just good enough at not letting them die.

[farley101]

Ha! Even if you don't think so, I do believe you have to have a little skill to have plants that thrive as you do.

I live in a very urban area but have tried to add as many native plants as I can for minimal maintenance. Unfortunately those plants are thriving with the lack of competition they face in the wild, so I'm finding they are a bit more work than I was expecting. I grow lots of wildflowers that the bees love, so I'm happy to put in the effort!

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Also, appreciate the friend comment! I feel like the core of people on this board are really great, welcoming and helpful and I'd like to think we're all friends (unless they're jerks &#128518

I've gotten so much great advice from the OB, I really appreciate the input I've been given. Especially since I'm a rookie at this! Thanks everyone!