Using red lava rock for outdoor orchids?

[SaraJean]

I recently acquired a gorgeous Den. Spectabile from an orchid show in my area it looks as though is was recently repotted but I really don't like the media that it is in. The current media is way too water retentive for my taste since most for my guys are grown out in the elements. I am seriously concerned about root rot and would like to switch out the media to something very fast draining. Has anyone, especially those in hot and humid climates, had much experience growing their dens in red lava rock? Some people say it is too water retentive, others say it dries within a day. I have also seen an article stating that it changes the ph of the water (can't recall off hand if it made it too acidic or too alkaline). I also have some leca that I could use or combine the two together.

I am also wondering if there would be any difference in switching pot types. It is in a net pot right now, could switching to clay do more harm than good? I like clay simply for aesthetic reasons and don't mind experimenting, but this orchid is too pretty to kill over something petty

Thanks!

[Subrosa]

I don't use it much for orchids, but I can tell you that in aquariums it can lower the pH due to residual by products of the volcanic activity that formed it. These by products can be strongly acidic. I would think this would be less of an issue if it's broken down into pieces small enough to use as orchid medium.

[pipsxlch]

In my experience, it can work great- with the clay pot also. Quick draining and maintaining airiness is one of its biggest perks. I prefer it to bark mixes, though out of laziness/availability I do often use bark.

Leafmite here I believe uses it exclusively, though she isn't a year round outside grower.

[SaraJean]

I should also put it out there that I am lazy. I don't want to keep repotting every two years and disrupting the roots just because my media keeps breaking down fast with my humidity.

[Leafmite]

I use red lava rock for nearly all my potted orchids (Phrag is in LECA and the Vanilla is in soil/sand mix). I pair it with basket/net pots.

Red lava rock is nice because no matter how much/often it rains when the orchids are outside, you never need to worry about the roots rotting. It never compacts over time like bark does. When it is hot, I can water away and not worry that the medium is rotting. I don't need to keep spending money to replace the medium and, instead, can spend it on buying more orchids.

Some things I have learned with the rock is that you need to flush it well (I have other plants and the soils also need flushed, too) to remove excess fertilizer that builds up. It helps to add a bit of Calcium to the plants (Cal-mag) if your water doesn't have enough (or if you get quite a bit of rain). When re-potting, be careful to stake the plant very well and not move the pot for a few months until the roots are well-established (the rock is sharp and if you move the pot, they can cut new, delicate roots).

[pipsxlch]

Then I think it could work for you. The laziness I referred to is in locating local sources for appropriate sized rock. With inorganic media like this, you don't have to repot as often as the media isn't breaking down.

I only use clay when I use a traditional pot due to heat/moisture retention issues. I've used it successfully with many dens including spectabile. I haven't had the good luck with net plastic pots that I've had with wood baskets- or clay for that matter. Anymore I only use net pots with things that want a lot of moisture like oncids.
Just what works for me though, your experience may be totally different.
(plastic baskets have worked well for me though)

[SaraJean]

Originally Posted by Leafmite

Red lava rock is nice because no matter how much/often it rains when the orchids are outside, you never need to worry about the roots rotting. It never compacts over time like bark does. When it is hot, I can water away and not worry that the medium is rotting. I don't need to keep spending money to replace the medium and, instead, can spend it on buying more orchids.

THAT'S what I'm talking about! And yes, I will definitely flush more frequently. I can treat it like I do my s/h ones. I hadn't thought about the roots getting cut on the rocks, so I will keep an eye on that. Thank you!

---------- Post added at 09:14 PM ---------- Previous post was at 08:44 PM ----------

Originally Posted by pipsxlch

Then I think it could work for you. The laziness I referred to is in locating local sources for appropriate sized rock. With inorganic media like this, you don't have to repot as often as the media isn't breaking down

I hear you on the laziness you refer to. I went to 5 different garden centers before I found any lava rock that wasn't in some god awful massive quantity. I just want to wake up and have all of the stuff I need waiting on my doorstep; maybe I should sign up for Amazon prime I never care about tending to my orchids daily but just the thought of repotting turns me into a procrastinator

[lacivic99]

I keep my top-heavy dendro in a clay pot with 1/4inch lava rock. It's been working extremely well indoors. The 1/4 inch works well for the finer roots of this dendro, and maintains enough moisture indoors, while the clay pot ensures the excess moisture is wicked away. If you are growing outdoors, I would consider going with a larger 1/2 size.

[ramonypony]

I've only been able to find it in a bulk bag with large pieces. They're too large for me to use on their own because I don't want to water every day. If you can find small enough pieces lava rock works great with dendrobiums. I like to mix it with bark for my cattleyas, especially in plastic pots because it weights the pots so they don't tip over.

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[mexicowpants]

I prefer to use white pumice stone for pretty much all my orchids, the exceptions being the more moisture-loving ones such as paphs and stanhopea. I even have a catasetum in pumice which is positively thriving. A little faster draining and less water-retentive than red lava, it's almost impossible to overwater. It's also softer and much less sharp than red lava, and therefore much kinder to roots during repotting. Downside? Yeah, if course there is. It weighs practically nothing, so you'll have to find another solution to keeping your top-heavy plants upright. So light, in fact, that it floats, so moderate-speed watering is strongly advised unless you want half your media all over the floor!

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