Sorry for the long delay with answers, I will try to catch up...
Hello All,
OK, I noticed that your newer pictures have the crushed oyster shells on the top whereas your older pictures did not. Are your older kovachii from 06 still alive? Did you add oyster shells to them also? Or do you not need to after they reach a certain size?
Yes all of my kovachiis are still alive.
I have added oyster shell or crushed limestone to all kovachii.
I think kovachii will benefit from limestone presence through all stages of growth. I will explain later on.
I emailed Ray and he thought there might be enough calcium in the MSU Pure water formula but wasn't sure. Do you add the oyster shells for additional calcium or to raise the pH? If it is for calcium can you just add a calcium supplement?
I added oyster shells to both add calcium and raise the pH. Also top dressing restricted the air flow through the media. Contrary to normal s/h practice this is what I wanted to do. The leca is to coarse for small seedlings unless they are top watered frequently or maintained in a very high humidity. With new seedlings the new roots come from the base of the plant which sits on top of the leca pebbles. The very surface of the coarse leca stays too dry to support a perfect environment for these delicate new emerging roots. By top dressing with oyster shell the moisture content of the media surface is increased and more humidity is maintained in the upper zone of the pot. This creates a better environment for the new "baby" roots.
I do not think the added Calcium from the oyster shell dissolving plays much of a role with kovachii. I did trials using
additional Calcium Nitrate and the results were not dramatic. However kovachii does want more Calcium than MSU fertilizer provides.
That brings me to my biggest question that I hope you can answer. I've searched but can't find anything specific about pH of water and fertilizer solution and PrimeAgra. I can find the pH of the soil/medium kovachii naturally grows in (7.9), and I can find the pH of the rain water kovachii naturally gets (6-6.5). However, I don't know how to apply that to PrimeAgra. I understand the soil/medium will raise the pH of the water and I know kovachii likes more alkaline conditions whereas most other orchids need a slightly acidic environment to absorb nutrients.
Alfredo Manrique in Lima was kind enough to show me a bag of freshly collected soil from the root zone of a wild kovachii. The soil consisted of chunks of limestone and clay. NOT MOSS. The pH of the soil will be high. The flowing water will be direct rain water and the pH will be near neutral. So much rain falls in the habitat that the water does not have much chance to saturate with salts or minerals before it passed through the root zone. The roots need to be wet and the soil is not well aerated at all.
I'm assuming that PrimeAgra will not adjust the pH up or down so we can limit/focus just on our water fertilizer mix pH. Since I've read kovachii likes slightly alkaline conditions could I/do you adjust the pH between 7-7.9? But then if so does this restrict the plant in being able to take in needed nutrients?
Do not assume PrimeAgra will not effect the pH. In all my sampling, the pH of PrimeAgra was constantly dropping low.
With my kovachii I have not seen pH to be super critical although higher is better than lower so I would not say kovachii must have an alkaline media.
Rather than trying to adjust the pH up I would (I did) add limestone to the media. Mix crushed limestone or oyster shell throughout the pot, not just as a top dressing.
My thinking is also that maybe in its natural habitat the alkaline soil balances the acid in the water and the sum is slightly acidic and it can still take in nutrients? Maybe the reason why people are adding oyster/calcium chips and lime is to overcome the acidity of the medium and then the fertilizer/water solution they are adding.
I think the roots of kovachii want to be in direct contact with wet limestone. There is likely a benefit for the root hairs to actually touch the mineral that goes beyond simple pH.
It seems like there are so many possible variables and since you have much more experience with kovachii in S/H maybe you have figured out all this pH stuff. I did read that someone asked you about this but you had (I think) left your pH meter in Peru and had not been testing pH.
I have since retrieved my pH meter. Normal low pH will not kill kovachii. High pH will not make kovachii grow faster. Don't get to preoccupied with pH, just keep it from dropping too low.
I also read that you were just using the MSU at 50 ppm Nitrogen and then going to 100 ppm when they got a bit bigger. However my own testing of MSU and pH is that even the pure formula drops the pH down to the 5/6 pH range, of course this is using 125 ppm nitrogen.
This is the problem with trying to replicate Nature. How to maintain a high media pH while applying an acidic fertilizer. There is no simple answer. I do not think you can even come close with true s/h culture. You need to constantly refresh the media with irrigation water. By washing the media with the nutrient solution frequently you will keep the pH from falling lower. But the you will be hydroponic and not simi hydroponic. But who cares what you call it.
Well, I hope this makes some sense, if it doesn't please ask for clarification. I guess to sum it up have you found the best adjusted pH value for your water and MSU RO formula mix that kovachii likes? Do you have to supplement calcium chips/oyster shells to the mix for older kovachii plants? If so is there a more elegant way/amount of adding calcium? Am I missing the point entirely concerning oyster shells and they are needed for another reason entirely.
Your questions make sense.
Mix limestone into your mix, this will in effect adjust your pH.
Add Calcium with periodic irrigations of Calcium Nitrate if you want to be elegant.
Water often and do not rely on wicking of the leca.
Keep the humidity of the soil surface high (wet).
Any other questions?
P.kovachii grows well in leca especially fresh out of the flask.
For several reasons I am now growing all my kovachii in a more traditional mix.
I'll try to get some current photos posted, a few plants are on their 3rd growth but they all grow slowly compared to hybrids.
