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I think your Cattleya experiment is giving minimum winter rests to plants and we will now get to see what they do. The windowsill gave them a natural winter rest with reduced day length, reduced light intensity because of the sun angle, cooler temperatures, and probably you reduced watering and...

Is that four flowers on one spike?

So, if you chronically have a substantially acidic pot medium (most likely this is an organic medium) and you want to counter this long term, dolomite could be top dressed (or mixed in) to gradually release buffer that would bring the pH up. It is not a very effective way to increase Ca or Mg...

Roth, do you think urea fertilizer only works with organic media with a strong microorganism population? Do you think it can work with LECA as the medium, an almost hydroponic situation with intermittent fertigation from above?

Dolomite is a mixture of calcium and magnesium carbonate. I think I am understanding you to say that you put a layer on top to mostly to provide the carbonates for buffering of the acid fertilizer OR do you think it is also providing necessary additional Ca and Mg?

Your collection of the old records is extremely valuable for those of us who really like orchid history and the evolution of plants and awards. How did you collect them? Currently, we focus strongly on individual flowers and forget that in the 1920s through the 1950s these Cattleyas were for...

Can you even compare and contrast the wonderful group of white hybrids that you have?

Some very interesting things to me. Registered in 1951 by A. Joseph, the hybrid name certainly suggests US origin and I apologize for not being able to find out who Joseph was. He was likely important to our orchid past. The first cultivar to be awarded was 'Orchidglade' in 1954. Twenty-three...

I think the pH of the solution only matters for the short amount of time that the solution is first in contact with the roots. The velamen absorbs the first things that hit it. If the ions are in solution, they will enter. Most of the rest of the fluid leaves the pot, depending on the medium. If...

Will be interesting to see what Roths says, but I think he has not been doing this with kovachii because he focuses on getting the pH correct with fertilizer with good amounts of nutrients, including Ca and Mg.

Citrate is used as a substrate for metabolism by a number of bacteria involved in fermentation, so maybe it is being actively used in the solution. The cloudiness could be partly from microorganism growth. I don't want to use citrate to lower pH or the basic potassium salts to raise pH. When I...

We need to know your water, fertilizer, fertilizer concentration, fertilizer frequency. If you happen to know the EC and pH of your fertilizer concentration some of us will be very pleased. If you don't, we may be able to infer it based on your water and fertilizer.

I think you are probably right. The higher the pH, the more bound to other things Ca, Mg, and P become, reducing the available ions. It doesn't make sense to try and feed kovachii at a pH of 8.0. Although I have purchased dolomite and crushed oyster shell, I am thinking I will not use.

So, if you have Ca at about 80 ppm and Mg at about 20 ppm in a fertigation solution at a buffered pH of 5.8, you have enough of those ions available for most orchids, including kovachii? In that situation is top dressing with dolomite (or crushed oyster shells) adding anything?

Roth, ignore the foliar analysis. How do you assess the “soil” analysis by Manrique? Do you think that indicates a higher pH/higher Ca medium for growth? Or, do you think that in pure LECA (Hydroton) receiving intermittent fertigation from the top that a pH of 5.8 solution with 80 ppm Ca would...

What a great collection of heirloom albino Cattleyas you have.

I took a screen shot of the following section from a September 2008 Orchid Digest article by Alfredo Manrique. His analysis seems to indicate that Phrag. kovachii takes up/needs more calcium and magnesium. The higher pH of the growing media is from the calcium (and probably magnesium)...

What do you think about the orchids that are supposedly calcareous, like Phrag. kovachii (I know there are some Paphs that may be calcareious)? Do you think it is mostly about wanting more Ca ion or is the higher pH important for various reasons?

I have always admired the OL picture of ‘Elly’ and your pictures confirm that. I have been reluctant to risk my growing conditions with a pretty expensive plant. Do you have a reasonably large Cattleya collection? Grow indoors or in a greenhouse. We are both in Minnesota.

What form of limestone do you use?