Adding lime to Orchiata

[Jugyjoy]

Well, I’ve learned that Orchiata is amended with some dolomite (to raise its ph as Pinus Radiata is otherwise too acidic). The manufacturer recommends liming it every 9 months or so because the dolomite gets exhausted. I have googled how to do it and it appears that you have to unpot your plant and remove the bark. Then, you leave the bark to dry out, and when dry, you add a small amount of lime. Apparently you have to do this repeatedly. raising the ph in small increments until you get to 6.5. The problem with this is that you disturb the plant which would sooner be left in peace. Then again, if you don’t do it, the ph drops too low and the orchid finds itself sitting in a very inhospitable medium. Do you lime your bark? If so, how do you do it?

[Roberta]

I never heard of that one... and have plants that have been in Orchiata for multiple years. Before considering this "actionable" I'd do some testing - run water through the pot, and check the pH of the effluent. Where I live, the tap water pH is about 7.8, I tested effluent of a pot that contained cheap (not Orchiata) bark that was clearly broken down and the effluent was pH about 7.2. Even a really "acid" mix, the broken down stuff, couldn't change it much. If you water is more pure, with lower pH to start with, your results may differ. So test...My suspicion is that this is not an issue in the real world.

[Jugyjoy]

Yes, need to test prior. I will paste here what the manufacturer says just fyi:

Dolomite is a natural mineral that contains calcium and magnesium. Research shows dolomite addition to substrates is very beneficial. We add dolomite to Orchiata to:
Stabilise the substrate by increasing the pH to within a range of 5.5 to 6.5
Prevent salt accumulation
Provide the minerals calcium and magnesium, essential for plant growth
The dolomite in Orchiata provides the plant with an initial start up supply of these two minerals. Growers must remember though that after a good length of time (around 9 months), dolomite will have broken down and growers must reapply dolomite or other liming compounds to maintain optimum plant growth.

[Roberta]

"Optimum plant growth" needs a bit of definition. I suspect that is very condition-specific. If my water were deficient in Ca and Mg, I'd be supplementing anyway, would not depend on the medium to provide. Actually, the majority of orchids prefer "slightly acidic" to "slightly alkaline". Noteworthy exception being most (but not all) Paphs.

I haven't seen sign of breakdown of Orchiata in even 5 years (Catts that don't stay wet, in baskets so they don't need repotting) For plants in pots, you're likely to be repotting sooner than that because the plant has outgrown the pot.

All that being said, Fred Clarke (Sunset Valley Orchids) prefers Kiwi bark (also Pinus radiata), which isn't treated.

[Mountaineer370]

I have never heard of this being something to worry about, either. As I mentioned in one of your other threads, I've been using Orchiata for probably around eight years. I repotted a bunch of Phals last fall, and a couple of them had not been repotted in three years. With all but one of them, I used the same Orchiata that was already in the pot, just added more for the larger size pot.

If the pH of the bark changes over time, it's not something that's showing up as a detrimental factor in my collection. I believe my plants are getting plenty of calcium and magnesium and other minerals from my municipal water supply and the fertilizer I use.

If that's not the case for you, then maybe you want to look into it, but I feel that there are other aspects of culture, like getting light, temperature, and watering optimal, that are far more important.

[Jugyjoy]

Thank you, ladies! 🙏❤️🙏