LECA vs Charcoal for Orchids

[Orket]

When would one use LECA and not charcoal and vice versa? To my knowledge, both are similar in that they do not break down and they allow good aeration to the roots. I would think LECA would retain more water due to its smaller size, as compared to charcoal chunks. How does it compare to charcoal chips and is there any advantage/disadvantage to using LECA rather than charcoal? Charcoal is definitely more cost effective though.

[Chris in Hamilton]

Charcoal isn't really used for aeration although it probably helps some. More for absorbing pollutants in the medium.

[JDT]

I would agree with Chris. One thing I would add being in an area where our heat and humidity is similar, charcoal will break down over time. I have some friends here that use LECA as the only media in some of their orchids, it is more expensive but in the long run you don't have to repot as often so it works out in the end for the extra cost, I use it in my media that I mix myself!

[Orket]

I see. Here everyone seems to use either charcoal chunks (dendrobiums etc) or sphagnum moss (phalenopsis) as the potting material. Most of mine are using charcoal with a top dressing of sphagnum/charcoal only/sphagnum only. The charcoal does seem to dry out too quickly for my liking but the dendrobiums dont seem to mind. Was hoping maybe the LECA might help with water retention...

I have a bag of leftover LECA from a failed hydroponics experiment. Im currently using it on a new Cynoches, so far it hasnt complained (yet). Would be interesting to substitute some of the charcoal for LECA at the next repotting to see what difference it would make.
Posted via Mobile Device

[JDT]

I see. Here everyone seems to use either charcoal chunks (dendrobiums etc) or sphagnum moss (phalenopsis) as the potting material. Most of mine are using charcoal with a top dressing of sphagnum/charcoal only/sphagnum only. The charcoal does seem to dry out too quickly for my liking but the dendrobiums dont seem to mind. Was hoping maybe the LECA might help with water retention...

I have a bag of leftover LECA from a failed hydroponics experiment. Im currently using it on a new Cynoches, so far it hasnt complained (yet). Would be interesting to substitute some of the charcoal for LECA at the next repotting to see what difference it would make.
Posted via Mobile Device

You should try that! I use sphagnum in my Cynoches/Catasetums and they love it!

[Barunario]

I agree with Chris. Charcoal is said to be capable of absorbing polutans (example : overdose fertilizer).
As for water retention capability, I think both are similar. I water every morning and every evening as I check the pot, it dries out completely. Maybe I'll check a few hours after watering this weekend. Fortunately my catts doesn't seem to detest this situation.

Oh and I live in Indonesia, you can say coastal area.


Cheers,
Baruna

[Chris in Hamilton]

I see. Here everyone seems to use either charcoal chunks (dendrobiums etc) or sphagnum moss (phalenopsis) as the potting material. Most of mine are using charcoal with a top dressing of sphagnum/charcoal only/sphagnum only. The charcoal does seem to dry out too quickly for my liking but the dendrobiums dont seem to mind. Was hoping maybe the LECA might help with water retention...

I have a bag of leftover LECA from a failed hydroponics experiment. Im currently using it on a new Cynoches, so far it hasnt complained (yet). Would be interesting to substitute some of the charcoal for LECA at the next repotting to see what difference it would make.
Posted via Mobile Device

I know in the Philippines Dendrobium are often grown in a split coconut husk filled with charcoal then tied back together. In that case, yes, it is being used partially to drain quickly. That works well where the climate is warm/hot because you can let water fly everywhere outdoors. In temperate climates and especially for people growing indoors you do need something to hold the water longer so straight charcoal wouldn't work.

[Dorsetman]

I don't think either material ( charcoal, leca) holds water itself, unlike sphagnum moss. It is on the surface of the chunks. And then the roots follow the surface of the chunks to get at the water. The capillary action effect which moves the water through the pot, works when the space between nearly touching chunks is just right - perhaps a fraction of a millimetre. So drainage, and water availability to the plants depends on the size of the chunks, and also on the surface texture. Rough surfaces hold the water longer ; smooth surfaces allow complete drainage. Quite a complex subject and I have never found any sensible scientific treatise on the subject ( but a lot of hooey which made me laugh out loud ). I did quite a bit of experimentation, using glass columns, and seeing tghe different rates of evaporation from the top etc., to apply to my own culture. But I couldn't make up "laws of capillary flow" from them.

[daenna]

Had success growing cattleyas using LECA as a medium. I just have to water them a little more often.

[Orket]

Recently, I posed this question to a local orchid nursery owner. He says that charcoal (large chunks, not flakes) retains water slightly better than LECA. Typically charcoal dries out in a few hours when used indoors, which is fine for Catts, Vandas and the like.

I repotted one of my dendrobiums into LECA out of curiosity and the results, although not "scientifically tested" :P seem to support his opinion. As I'm quite a reluctant water-er, guess I'll use the LECA for my hydroponics stuff instead.

The garden centre I frequent sells "orchid stones for cymbidiums", which seem to be pumice stones. How would these fare in comparison?

(Btw, just looked at the Cynoches that I mentioned earlier in this thread and it is potted in sphagnum now... haha I must have transferred it over at some point and forgot... it seems to be quite happy there though with lots of roots in the medium)