Inorganic media

[Leafmite]

Years ago, I grew mostly standard Cattleyas along with a mix of others but I have downsized to smaller orchids.

When I grew the larger Cattleyas, I used the one inch lava rock. If you use basket pots, moving it to a larger pot is just setting it into a larger pot with more rock, no need to disturb the roots. I always potted them into a pot that would allow growth for many years, though. The rock and basket pot allow plenty of air-exchange so rotting roots are not a concern.

Now that I grow smaller orchids, I use 1/4 inch lava rock. Like with the larger rock, the roots of the orchids I grow can grip the smaller rock so that, after a time, if I knock over the pot, most of the rock will stay in the pot.

What I am growing in the 1/4 inch rock:
small Cattleyas, Zygos, a Dracula, a Paph, two Phals, a Psychopsis, three small Oncidiums (Twinkle and the parents), and some Cyncs. Except for the Dracula (small basket pot due to the way it flowers), I use pots that have small holes all over for increased air-flow.

If you do choose lava rock, rinse the rock either outside or in a bucket that is dumped outside as the dust can clog sinks. Flush the rock well, now and then, with water to get rid of any excess fertilizer that is unused. Always stake and wire the orchid very well in the pot when it is first planted as the rock can scrape, cut roots if the orchid moves. Once the roots are well-established, this is not a problem. I would pot the new Cattleyas in the rock in the spring and, by the time I brought them inside in autumn, I could remove all the wires/stakes. If you have any rootless Cattleyas, just stake them over the rock and water the rock well when you water the other orchids. The humidity will help the new roots grow.

If you have any smaller orchids, mounting is another option. I have a nice collection of small mounted orchids, including a Cattleya walkeriana. I was thinking of mounting the Cattleya schilleriana and aclandiae but they are doing well in the 1/4 inch lava rock and I hate to disturb them.