Vanda coeruea problem

[Rick]

DUNO recommends 8-5-25 for aussie natives. He said to avoid high N fertilizer like the plague..... He said that they need the extra K for the carbs and sugars....

Maybe the species that annually produce big underground tubers are a special case, but this recommendation is a rarity. K ends up more concentrated in roots fruits and flowers, but K is not much of a component of carbs and sugars (almost nothing but carbon and hydrogen), but K is used in the enzymatic reactions to make carbs and sugars.

There are several articles by potash industry associations that don't go this extreme.

http://www.extension.umn.edu/distribution/cropsystems/dc3425.html

Here's an article on potatoes. An annual plant pushed for high production in short time frames. This falls within the N vs K levels Stone has seen in literature, but doesn't advocate reversing priority of N to K fertilizing.

Note in the first chart the relative amounts of NPK Ca Mg in production vines versus the tubers.

 

[Stone]

I'm looking at Dutch figures for optimum growth of a range of hydroponic crops ranging from Tomato to Chrysanthemum, Rose, and Cucumber etc.
K levels in every case are over 100% of N levels and Ammonium approximately 10% of Nitrate.

These figures are for plants grown in totally inert media with probably very low cation exchange and on continuous feed. It shows how much K plants can use given certain circumstances. Of course it doesn't necessarily follow that we should feed paphs like that because as you say most of the organic media we use has high to very high levels of K in it along with the capacity to hold even more. Mineral soils also usually have a good amount of K in them
as your paper says so these figures aren't applicable there either.
But I use fert. within this range for all my epiphytes on cork and they do extemely well. With paphs though, I will try to cut K percentage because of the interference with Ca and Mg you've been talking about.
The important thing for me is good root and as you know Ca is vital for root growth and good root growth is essential for Ca uptake.

 

[Rick]

I'm looking at Dutch figures for optimum growth of a range of hydroponic crops ranging from Tomato to Chrysanthemum, Rose, and Cucumber etc.
K levels in every case are over 100% of N levels and Ammonium approximately 10% of Nitrate.

These figures are for plants grown in totally inert media with probably very low cation exchange and on continuous feed. It shows how much K plants can use given certain circumstances. Of course it doesn't necessarily follow that we should feed paphs like that because as you say most of the organic media we use has high to very high levels of K in it along with the capacity to hold even more. Mineral soils also usually have a good amount of K in them
as your paper says so these figures aren't applicable there either.
But I use fert. within this range for all my epiphytes on cork and they do extemely well. With paphs though, I will try to cut K percentage because of the interference with Ca and Mg you've been talking about.
The important thing for me is good root and as you know Ca is vital for root growth and good root growth is essential for Ca uptake.

Your data base brings up the points I've been making all along. With the exception of the roses, all the other plants are annuals. Going from seed to harvest in less than one year, and plants are selected for maximum fruit or tuber production (which also requires/sequesters K). The potato link in my earlier post is in the same "agri-application" type. If you switch to perennial crops like fruit/nut trees, coffee bushes.... in non hydoponic settings the K use drops dramatically. The GA ag extension recommendation for pecan nut growers indicates no fertilizing at all except for rare additions of N and zinc. Leaf tissue values of pecan trees (which matches the values for tropical leaf litter) has low levels of K in leaf tissues.

Another issue with high K is that plants become susceptible to disease. I've distributed a short paper on this to a handful of ST members on demand. I'm hoping that eventually ST may have a library function that we can upload papers to). The disease problems in the paper I referenced were Erwinia bacteria attacking annual plants like beans. Going back to the high K hydroponic growing methods for perennials like roses and orchids reminds me of all the posts on things like crown rot, soft leaf rots, botrytus, black mold.....which seems to plague are orchids and roses grown with these standardized agriculture fertilizers. Subsequently we have standardized the practice of heavy use of anti bacterial and anti fungal chemicals and practices of "only water in the morning" and "don't get water in the crown".

I have seen amazing plants grown under high K feeding regimes (some in my own GH). Ive seen many of these same plants crash and burn the year after coming back from a show with a CCE. Ive also seen plenty of CCE quality plants grown with no fertilizing whatsoever, and have been extra impressed that some of these plants have been in the owners collection from decades with no extra special care or consideration. No use of crazy chemicals.

I realize that growers have a zillion strategies to accomplish there growing goals, I'm just finding out how much the low effort versions are all converging on the same basic formula.

 

[Rick]

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Good and bad roots before and after K reduction V. sanderianum


Potting method and roots of V. roebelingiana

Mounted Esmerelda clarkii. Generally considered a difficult cool growing vandaceous species. This plant was less than the palm of my hand when first purchased less than 2 years ago, and growing very quickly on a low K diet.

 

[Rick]

Also depending on how you look at it, some people consider mounting another form of hydroponic growing. Except exposure to feeding media is once a week instead of continuous to once and hour.

 

[Makule]

The knotty roots may also be related to the plant itself, as alluded to earlier. I have had several V. coerulea and some show that trait while others do not. All types are grown in the same area under the same conditions and culture.