# Potassium Monophosphate



## Brian Monk (Jul 28, 2011)

I have been reading quite a bit about Cymbidium culture recently, mostly because I am partially responsible for a collection of several hundred Cyms. 

Monopotassium Phosphate is used by commercial growers to shut down vegetative growth. The heat-tolerant ensifolium hybrids will continue to grow into October here in south Florida if I let them, so this is a particularly good application for me.

I also intend to use it for some of my Australian Dendrobiums, and a few Cattleyas that need to stop growing in order to bloom better in the winter (loddigesii, walkeriana).

My question is, would this technique work for Paphs? I think this technique may be more appropriate for species that experience a definitive monsoon season, but I really don't know the answer to the question at all.

Thoughts??


----------



## Brian Monk (Jul 28, 2011)

Sorry, potassium monophosphate.


----------



## paphioboy (Jul 29, 2011)

Paphs don't go dormant, per se, so I'm not convinced it will work as opposed to cyms and Aussie dends. Still worth a try on more 'disposable' plants.


----------



## Rick (Jul 29, 2011)

Plants in general rarely see high levels of potassium in their environments.

If you want to use more K then make sure you balance it with an equal amount of calcium nitrate, and a dash of epsom salts.

Also if you are using CHC you will "poison" the CHC. It will discharge any divalent ions (Ca/Mg) in preference to the K. Ultimately you will end up with a Ca and Mg deficiency in the plants since excess K at the roots blocks the uptake of Ca. Bark and sphagnum will also do this to some extent. If you are determined to try this, then you should stick to mounted or SH systems so that residuals can't be accumulated.

We've had a lot of discussions about the K Ca Mg relationship lately.


----------



## Brian Monk (Jul 29, 2011)

YEs. I'm not convinced completely that the arguments concerning low potassium are completely valid. But that really isn't the point. Artificial systems being what they are, and manipulation being what it is. I am talking about manipulation of the environment outside of a natural system.


----------



## Rick (Jul 29, 2011)

Brian Monk said:


> YEs. I'm not convinced completely that the arguments concerning low potassium are completely valid. But that really isn't the point. Artificial systems being what they are, and manipulation being what it is. I am talking about manipulation of the environment outside of a natural system.



Understood. Use of CHC is also an un-natural media, and I think has inherent problems for use with paphs in conjunction with high rates of potassium supplementation.

Jim Tooney added a post about supplementing during the fast growing season in Florida, that included a shot of K in conjuction with Cal nitrate and/or epsom salt. This advice came from a large comercial grower who produces a lot orchid biomass anually.

I think for really fast growing plants during the fastest growing times you can speed them up a bit more with a shot of K.

Most of the use of K has been developed for fast growing, single season to harvest crops, and there's a ton of easy to get litterature on the web for review. Because expert farmers measure the available K, Ca, and Mg in soil, and know with a high degree of certainty what the standing biomass of crop will be at the end of season, they can tell you exactly how much K will be needed per acre of crop produced. Farmers have figured out exact K applications (frequently the soils already have plenty of Ca and Mg, but if that was deficient would include a dolomite application) for all common crop species. Things like corn wheat, rice, carrots get a relatively high amount of K. Species like coffee, that have relatively small amount of harvestable biomass, get very little K.
The amount of K needed is dependent primarily on the amount of harvestable biomass and no inherent differnces in species physiology.

But our hobby orchid application is different. We have relatively slow growing plants that live for multiple years that have little biomass lost to anual harvest. 

I've mentioned that I have an article on the predisposition of (non orchid) plant species to disease genera (like Erwinia) when K leaf tissue exceeds Ca and Mg. It just occured to me that one of the prime orchid feu-pas, watering at night causing rots, may be another case of "un natural" fertilization practices for the sake of getting "un natural" high growth rates.

Kind of a live by the sword die by the sword thing.


----------

