Sawdust mix for Catasetinae

[euplusia]

I have been using this mix over three full growth cycles now, for about 300 plants. So I can say it is tested.
I did not notice a nitrogen deficiency. I mostly use a balanced fertilizer, because I was afraid of rot when giving too high nitrogen doses. The sawdust does not decompose within the first year. And then I prefer to repot.
Pet Shops are often a good source for clean unexpensive potting media. Bird grit is an example.

[NYCorchidman]

Nice info!

Also, thanks for the photos.
I see that not all "resting" catasetums lose their leaves.

[Bud]

I understand your concern, Steve. But New York City have an array of botanists that monitor if a tree is sick and the whole tree is disposed of and the mulch is incinerated. I have seen it done. The sawdust I have is from healthy trees and they were just pruned. The trees I mentioned do not have toxic sap that make orchids die; in fact they are used for mounting.

---------- Post added at 02:02 AM ---------- Previous post was at 01:56 AM ----------

....trivia: the sap of pine trees if ingested by humans can give them stomach ache but they will not be hospitalized.

[euplusia]

This pic demonstrates the increase.
I prefer sawdust from ripe heartwood, not from bark. But a bit of bark does not harm.
I avoid used wood with residues of chemicals, paints and varnishes, timber preservative etc.
Sawdust of a chainsaw from beech, hornbeam, birch, ash, poplar, elder, apple and pear tree are promising, to name a few.