Corybas diemenicus

[SteveC]

First time that I have flowered this tiny Corybas diemenicus, aka Corysanthes diemenica. It hails from Australia; Victoria or South Australia to be precise. When I say tiny, the whole plant would fit under a UK 5p or a US penny.

Elsewhere on the forum I have seen these described as easy or beginner's plants but some accomplished growers here in England have had trouble with them rotting off so I just hope that I can keep them going.

[MamaLiberty]

Oh, my goodness! How interesting. I would never have dreamed there could be such a tiny orchid. Used to have a big terrarium (made from a leaky old fish tank) where I kept a collection of different kinds of moss and a few miniature house plants. Orchids like this would have been a super addition. I'll have to rethink the possibility of doing something like that again.

[SteveC]

I think that they would like it in a terrarium, shady, humid, but cool. The biggest problem would be finding the tubers if you ever had to strip it down. They are about the size of half a grain of rice!
On second thoughts they might rot when dormant so not so sure.

[katrina]

oh my...I'm afraid I would lose that little one. So, so cute though. Reminds me of something out of a sci-fi movie.

[WhiteRabbit]

Wow! Awesome!

[King_of_orchid_growing:)]

Originally Posted by MamaLiberty

Oh, my goodness! How interesting. I would never have dreamed there could be such a tiny orchid. Used to have a big terrarium (made from a leaky old fish tank) where I kept a collection of different kinds of moss and a few miniature house plants. Orchids like this would have been a super addition. I'll have to rethink the possibility of doing something like that again.

Like Steve had said, it'd work for the growing season. During dormancy, it wouldn't hold over quite as well. Tuberoids are easy to lose if you drop them or if your enclosure is very large. The tuberoids are very small, (about 3 mm in diameter).

Corybas species from Malaysia/Indonesia are humid and intermediate to warm growing. They also have a distinct wet and dry season/growing season and dormancy period. These guys are primarily found growing on limestone outcrops and rocks with moss growing on them.

Corybas diemenicus is primarily found growing in granite type of soils with some vegetative debris.

I think you're better off growing them in a deli cup with holes used for transporting pet reptiles, amphibians, arachnids, and insects.

These orchids tend to be very easy to rot out during the dormancy periods. They have to be taken care of properly or you could lose an entire colony really fast.

I don't recommend these to beginners. They are more for intermediate to advanced level hobbyists who are somewhat familiar with growing orchids that have tuberoids. Because of their diminutive size, they are far trickier to grow than something such as Ophrys or Anacamptis.

[Andrew]

Steve,
Personally I find the Europeans harder to grow than many Australian terrestrials so the problems the English growers have with Corybas might be due to familiarity with how Australian terrestrial requirements differ from the European species. The Corysanthes-type of Corybas are the easier of the Australian Corybas to grow and while they aren't as easy as Pterostylis curta, my native orchid society still recommends them as good starter plants. The tubers are small and are prone to desiccating in summer so they do better with a bit of moisture in the pot during their dormancy. The mix shouldn't be damp but it shouldn't feel dry and dusty either.

As far as how Australian terrestrial culture differs from European terrestrials, I've found a lot of European growers recommending leaf moulds from birch, etc in their mixes. Australians who use leaf mould in their mixes usually choose Eucalyptus, which is much more fibrous and slower to break down and probably makes the mix a lot more open than birch or oak leaf mould. I'm not sure what is on the surface of your mix but it looks a little wet. We typically topdress pots with a layer of fallen Casuarina or pine needles. This keeps the mix off the leaves and lifts the leaves off the surface of the mix so that leaves and collar dry off quickly after you've watered. Even when we put covers over Corybas to keep the humidity up the topdressing stays quite dry. eg this incurvus:

[SteveC]

Thanks for this Andrew.
Pterostylis curta, coccinea and fischii grow like weeds for me. I give loads away or my greenhouse would be full of them!
I do not know use any leaf mould in my orchid mixes. Beech was recommended, but the leaves took years to break down and I could not make enough. I tend to use a layer of fine grit as a top dressing, pine needles not being easily accessible in this part of the world. I had just watered when I took the photo.
Going off topic slightly, I find most of the available Pterostylis easy. My Thelymitras do fine, my Diuris bulk up but are flower shy, but Caledenias are really difficult. Any thoughts?

Finally I guess the overall problem may be geographical. Very few people in Europe grow the Australians and since the arrival of CITES they are really difficult to get hold of. We do not have a lot of experience of growing them in our climate, with materials available to us. Presumably the situation is similar with European plants in your part of the world. Obviously forums like this help!

[Andrew]

Originally Posted by SteveC

Going off topic slightly, I find most of the available Pterostylis easy. My Thelymitras do fine, my Diuris bulk up but are flower shy, but Caledenias are really difficult. Any thoughts?

That sounds about right.
I don't know which Diuris are available in the UK but a lot of the species with long tubers like orientis, longifolia, etc flower better in their second or third year in the pot so if you repot annually and break apart the clusters of tubers, you won't get many flowers.
Caladenia are difficult to grow. I don't think there is an easy way to get around that. I don't grow many of them as they need more attention than I have time to give. A couple of species like latifolia are good growers but most species tend to have a strong fungal association that is difficult to maintain long term. In general, avoid repotting to minimise disturbing any fungi in the pot. If you have to repot, keep a few cm of the stem attached to the tuber as this is where Caladenia fungi is supposed to reside and the fungi is thought to reinoculate the new shoot as it grows through the old stem. Probably the best way of repotting Caladenia I've seen is to put the pot on top of another pot and let the plant send the new tuber down into the 2nd pot.

Originally Posted by SteveC

Finally I guess the overall problem may be geographical. Very few people in Europe grow the Australians and since the arrival of CITES they are really difficult to get hold of. We do not have a lot of experience of growing them in our climate, with materials available to us. Presumably the situation is similar with European plants in your part of the world. Obviously forums like this help!

Yes, it's the same situation with European terrestrials in Australia. When we can get hold of them, we're pretty much trying to guess how to grow them based on what we think the Europeans are doing and we don't usually have many plants available to experiment with different conditions. I've been lucky enough to have had people who are considered some of the best Australian terrestrial growers show me the ropes of growing our native terrestrials. There's a lot of aspects to growing these plants that we either take for granted or do without realising that make a lot of difference to how well these plants grow.

[801229001]

Amazing! corybas are very very hard to come by it seems. they are some of my favorite orchids!