Lava rock instead of perlite

9 years ago

I don't use much bark for regular orchids like Cattleyas Oncidiums etc but do in the cold house for the Cloud Forrest plants. The routine there is to start of small plants in sphagnum moss and when they get big enough switch them to bark mixed 3 to 1 with perlite. The perlite adds air to the mix. I was talking to John Leather from Hawk Hill and learned that they stopped using perlite a couple of years ago and use 3/8" lava rock instead.

Bark is preferred as SM has to be replaced every year. Pine bark does not lasts much longer and gets way too soggy as these plants get watered every 2 days. Orchiata on the other hand, does well in this situation.

The reason is that orchiata bark lasts so long that perlite deteriorates and becomes degregated before it is necessary to change the bark which can last up to 5 years. Lava rock also aerates and retains moisture which orchiata does not. I got a couple of bags of the stuff and mixed up medium orchiata bark with it at a 3 to 1 ratio. Repotted some Masdies with it and will see how they do.

It does make sense I plan to switch over from this point on.

Nick

Comments (3)

jane__ny
9 years ago
I haven't tried it in Florida but did try lava in NY. I didn't like it. I found it held too much moisture.

I have orchids from Odoms which came potted in a grey, slate type rock. It is light weight. I love it although it is hard to find locally. I find Cattleyas do very well in it. So far they are the only nursery I have found which uses it exclusively.

I am a bad waterer and let my plants go too long between waterings. I am working from rain-barrels and it is more time consuming than using a hose. No excuse, but the reality here.

As a result, I have started mixing some bark with this grey rock (I think its called Stalite). With some plants I'll mix in some perlite or sphag to increase moisture retention.

I'm still finding my way in this terribly hot climate but the Catts seem to like the combination.

The Phals I grow go in sphag mixed with bark. Some of the large Phals with thick roots will get some rock mixed it.

Nick, you water regularly and I don't. I am finding the Orchiata stays very dry. I haven't tried the smaller size and maybe that would work better for me. I also use the long strand sphag which I find holds up better...maybe that's because it doesn't stay wet. I don't know but I've had luck with that.

I might give lava rock a try in Florida. It might hold more moisture and get me an extra few days.

Jane
orchidnick
Original Author
9 years ago
I'm using the lava rock/orchiata combination on Masdies, Dracula, Pleuros etc. With one word moisture loving plants. I would not use it on Cattleyas Onc etc to moist. Tried it a long time ago and found it unsatisfactory for them.

Nick
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shavedmonkey (Harvey in South Fl.)Z10b
9 years ago
I use a lot of lava rock. It suits my heavy hand with the hose. I just changed an encyclia from a bark, charcoal, pearlite mix to all red lava rock. It was growing but blating blooms. I find that it holds water but will dry by the end of the day if watered early. Never rots. I use Orchid plus fertilizer, it has no urea which avoids salt build up in the lava rock. I fertilize full strength to allow enough time and water to flush the pots clean, every 2 weeks.

When i get plants that were potted in sphagnum I can't get it all off without harming the plant. So i surround the sphagnum with lava rock. It gives another zone of choice for the roots. Wet sphagnum or dryer lava rock.

I'm buying either 3/4" or 1".