Paph. delenatii question

[Tom-DE]

Thank you. I think I will ask HD people about limestone chips and hopefully get some. I saw the other day they had some landscaping stones but I could not tell if they were limestones.

 

[kman]

I’ve only used cal-mag for a brief period and have never noticed any difference. I use R/O and MSU

Something to remember is that most epiphytic orchids grow so slowly that patience is needed - along with careful observation and measurement, to really know whether a particular cultural practice is having a positive effect. In many cases there are so many environmental and cultural variables that years rather than weeks or months are necessary for any degree of certainty.

The only somewhat rapid change I've been able to positively notice is when I started adding urea to my fertility program. There the change was visible in days for Phrags and other faster growing species, weeks for Paphs. I've always used as a base a CalMag fertilizer, so can't comment on what it might be like without it.

 

[JustinR]

I have books by Lance Birk and Harold Koopowitz, as I recall they both concluded years ago that adding shells or limestone doesn't make any difference for most if not all paphs. So I never tried it, they seem to grow fine without it... but if it works for you

 

[Tom-DE]

I have books by Lance Birk and Harold Koopowitz, as I recall they both concluded years ago that adding shells or limestone doesn't make any difference for most if not all paphs. So I never tried it, they seem to grow fine without it... but if it works for you

It all depends on the water...and the species.

 

[Stone]

I have books by Lance Birk and Harold Koopowitz, as I recall they both concluded years ago that adding shells or limestone doesn't make any difference for most if not all paphs.

That depends on your water, your fertilizer and your potting mix. That is an unqualified, sweeping comment by those two authors.
Eg., If you use acidic mixes, use ammonium/urea and your water is very pure, you will kill your plants sooner or later. If you use alkaline mixes, use nitrates and have hard water, your plants will suffer all kinds of problems. If you use finely crushed powdered limestone you will see different results than if you use big chunks of limestone and do not make adjustments to cover that.
As an example, (but not with orchids), I once grew many hundreds of Clivias. I gave each pot a small handful of osmocote and nothing much changed for months (the colour of the leaves was just ok) but when I added a finely ground dolomite limestone mix, the leaves returned to a beautiful deep dark glossy green with one month. My water obviously did not supply enough of the required elements Ca and Mg and their carbonate forms to balance the ammonium N.