European Terrestrials Drop
 

Tarzane Group has just dropped a list of Mediterranean/European terrestrial tubers. For those in the US who want to give these a try, here's a rare opportunity to get these from a domestic source (so no shipping glitches that tend to happen when getting these from Europe) and the import paperwork has already been done.
SHOP TERRESTRIAL ORCHIDS. These will soon be waking up from their summer dormancy, so this is the ideal time.

I was gonna make a new post about this, but since it’s here, I might as well ask.

Hi Roberta,

I’ve read your input on Mediterranean terrestrial orchids in other posts, read the article about Scott McGregor you’ve mentions in past posts, and had to ask.

Potting medium? It sounds like perlite, pumice, and sand are standard for inorganic media, but what else can I use if I don’t have either on hand?
Is vermiculite, black lava rock, or akadama all ok to use?
Are there any inorganic medias I should avoid?
Also, media size? Should everything be in a fine-medium grade? Is there such a thing as too fine/coarse a grade for these? Is a mix of all three sizes ideal? Will the medium size affect how the roots or tubers spread themselves in the medium, or how the leaves and stems pop out from the top?

Lastly, I know I'm going to place them sideways when I place them into the medium since I can’t tell, but is there an obvious up or down side like tulip bulbs?

Sorry for the interrogation. Lol
Thank you

Hey, questions are what this forum is all about! Ask away.

For the inorganic part of the potting medium, it's passive so I don't suppose it matters a lot. I'm not familiar with akadama... is it neutral? (I use some kanuma with my Australian terrestrials since it is a bit acid which they want) European terrestrials should have a neutral to slightly alkaline mix. You could probably use "pea gravel" - I'd shoot for a particle size of around 3/16 inch whatever you use. (That is the size of pumice that I use and it mixes well with the soil, in any size pot) Having never used vermiculite, I can't judge on that one, but I suspect that it would have the same problem as perlite, too light when dry so pots would tend to blow over in wind. The goal is about 80% by volume inorganic and the rest organic, I use cactus mix from Home Depot for that part.

As far as the "which end up"... there is a little "nubbin" on one end, the other completely smooth i most cases. The bump is the top. That is where both new growth and the roots will emerge. After it has grown and bloomed, the new tubers develop on the roots. When you repot next year(during dry dormancy) you'll often find them still attached to the stringy old roots but they fall off easily.

Ahh thank you for all the insight.

I looked up the ph of akadama and the Internet said it has a neutral ph at 6.9. I’ll definitely try a few mixes and see which ones will or won’t work.

Regarding potting/repotting. Since the tubers I got from the Tarzane Group are about 1/2-1 in, should my pot size reflect that? Like a 1in tuber in a 2in pot or should I up the size to 3-4in to compensate for the root growth and future tubers? Does pot depth matter?

Thanks again.

Being terrestrials, you don't have to worry about overpotting. With luck, the number of tubers may actually increase for next year. I don't put any of these into anything smaller than 3-4 inch pots. Next year you may want to even go up a size. The rationale for not overpotting epiphytic orchids is that you want to allow for air flow and partial drying, and don't want a wet center of a too-large pot. Epiphytes in nature have their roots mostly in the air, of course in a wet and humid environment, we put them in pots to manage them in our less-than natural environment. Terrestrials, on the other hand, don't have that issue. During the growing season they want to be wet, when they are dormant they want to dry out and be ignored. So there's really no such thing as "overpotting" for these. Only reasons to keep pot size reasonable are shelf space and consumption of medium. (I'm lazy, don't want to mix up more than I need to, especially since I will probably do it again next year) In fact, when I repot, I put all or most of the old medium back into the pot, and then just add more to fill up a larger pot. If anything, you'd want to capture any mycorrhizae that may have established themselves. Since the medium is mostly inorganic, and dries out during the summer, there is nothing to break down and no chance for anything nasty to develop.

Next year, when you go to repot, you'll find the new tubers, the rest of what you'll find is quite dead. That's normal. There is no root system that carries over from year to year. All the energy from the growing plant goes into making new tubers for the following year.

Thank you for this. This totally helped me understand growing them a lot more than just the basic needs the internet can provide.
If anymore questions pop up, I’ll post again or dm you.

Thank you Roberta.