Mexipedium Ph

[keithrs]

I was wondering what ph everyone is use to grow them? Do you guys add limestone or oyster shells as a top dressing or use cal nitrate or both? Is it better to have a slightly higher ph medium?

I'm asking because I got a 'Windyhill' from Andy's collection. He couldn't really give me good info on how to care for it. He had it in bark and perlite. I want to put it in a shallow pot with inorganic medium mix.

 

[Rick]

I have been growing the Oaxaca clone for several years. I think that's the main one that came out of Windy Hill.

It's up to 20+ growths in a 12" pot. The base mix is bark with charcoal, perlite, but with plenty of limestone gravel, regular building sand, and "Cichlid sand" (which is mostly aragonite, a pH buffering sand for aquariums). The pot is also half full of styrofoam peanuts, so the bark mix is only a few inches deep.

I also use calcium nitrate to "dilute" the potassium in the MSU fertilizer I mix.

Actually I fertilize with 1/4 tsp MSU, 1/4 tsp CaNO3, 1/4 tsp of anhydrous MgSO4, all per gallon of very soft water.

I don't use straight RO water any more. I use a 10:1 mix of RO water with my well water and final hardness is between 20-30 mg/L as CaCO3

It likes lots of light and can tolerate high temps pretty well. They need to be watered as well as just about any paph. I think general Cattleya culture would be fine.

If you use the search function on this site you should be able to come up with lots of threads on Mexipedium culture.

 

[keithrs]

Thanks for the info Rick.....

Have you measured the ph coming out of your pot? And how about the ph of your irrigation water?

Thinking if I add more(mostly) limestone gravel and use a ph of about 6.5-6.7 to break down the limestone.... Kinda like a calcium reactor of a coral tank but no CO2 added.... Than I won't need so much CaN03 in my irrigation water. What you think?

 

[Rick]

It may be a bit hard to compare pH values with my irrigation water since it is so soft.

Pure water a gas balance has essentially 0 alkalinity and hardness, but pH is theoretically at 7.0 But with 0 alk and hardness, it doesn't take a lot of CO2 to have very low (~4) pH of pure water.

My irrigation water (without fertilizer) has a pH between 6.5 and 7. Hardness is about ~30 and alkalinity ~15. With fertilizer added, it will go to about 6 and will be more stable.

I haven't measured the pH of the Mexi pot. Since the upper portion of the pot is still mostly bark, I suspect the pot pH would run between 6-7.

The reason I use additional calcium nitrate with my MSU fertilizer is not to supply xtra Ca, but to 1) Maintain a nitrogen feeding rate of ~100ppm, and 2) to ensure there is always more soluble Ca than K in solution. I'm really more interested in "diluting" K rather than "adding" Ca.

Its not inconceivable that I may play around with a different formula that uses:
CaNO3 (to 100ppm N), a dash of phosphoric acid, 2 pinches of Epsom salts, a few drops of Protekt (for sconch of K but mostly silicates), and a 1/4 tsp of my seaweed extract (for organics, and trace metals).

 

[cnycharles]

that sounds like a recipe for a vanilla malted (with foam).... with a sprig of mint on top

 

[Ray]

Pure water a gas balance has essentially 0 alkalinity and hardness, but pH is theoretically at 7.0 But with 0 alk and hardness, it doesn't take a lot of CO2 to have very low (~4) pH of pure water.

That's what I always thought, too, but as the reduction in pH of pure water by dissolution of CO2 is an equilibrium relationship with the concentration in the surrounding air, for most folks having somewhere between 3.5-4% CO2 in the air, that should be about 5.3-5.6. That suggests that if it's lower, something else is contributing.

However H2CO3 is such a weak acid, almost anything overwhelms it and take over "control" of the pH.

 

[Rick]

That's what I always thought, too, but as the reduction in pH of pure water by dissolution of CO2 is an equilibrium relationship with the concentration in the surrounding air, for most folks having somewhere between 3.5-4% CO2 in the air, that should be about 5.3-5.6. That suggests that if it's lower, something else is contributing.

However H2CO3 is such a weak acid, almost anything overwhelms it and take over "control" of the pH.

You're right Ray for standard gas balance. And my post implies standard atmospheric or just exhalation pH.

The RO unit we have seems to pressurize a bit and strip out O2, so straight off the machine we have a higher percentage of CO2 than normal atmospheric and a lower pH.

Just shaking the water in a jar for a few seconds will raise the pH at least up to 5.5 and adding mild aeration for a short time will get it close to 7.

This was mostly illustrative on how pH is not always in step with alkalinity.

In the above case the pure water has 0 alkalinity the whole time the pH is running up to neutral. If I added a drop of dilute H2SO4 to the water, pH would drop below 4.0 (titrating for 0 alkalinity uses an endpoint of pH 4.2).

 

[Fawkes]

... The base mix is bark with charcoal, perlite, but with plenty of limestone gravel, regular building sand, and "Cichlid sand" (which is mostly aragonite, a pH buffering sand for aquariums). The pot is also half full of styrofoam peanuts, so the bark mix is only a few inches deep.
.

Huh... I bought a division of 'Windy Hill' a couple of years back when I was in St Louis to judge. Marilyn had it potted in bark - and it still is. I asked Marilyn about care later and it seems that she talked more about watering. I should have her message here - I will post it.

 

[Fawkes]

I was wrong... Marilyn does talk about limestone. I have converted her message to me to a web page and it can be found at:

http://www.proinnovation.com/Mexipedium xerophyticum characteristics and culture.html

 

[cnycharles]

thank you! .. for people looking for really large shallow plastic pots for potting things like mexipediums in, realize that you can take a cheap plastic waste paper basket, small or large garbage can or storage tubs and cut the tops off, melt or cut some holes in the bottom. My co-worker took the bottom of a storage container I had to make an outdoor tree bonsai container with

I'll bet orchiata would be great for mexipediums!

 

[keithrs]

Thanks for the link.....

That is a good cheap way to make you own pot.

Being so close to the border, I have access to all kinds of terra cotta pot for cheap. Cheap like $1.50 for a blue glazed 5"x4"x1" pot..... I would of liked a plain pot better but beggars can't be choosers!

 

[Rick]

I'll bet orchiata would be great for mexipediums!

Most likely:wink:

 

[cnycharles]

I have to repot mine, and I found an old tupperware cake container at my sister's while helping pack/clean for a move; easy to cut and melt some holes into (though maybe i'll wait to cut as the high sides might help keep humidity up in the winter) 'jewels from junk'

 

[cnycharles]

I was wrong... Marilyn does talk about limestone. I have converted her message to me to a web page and it can be found at:

http://www.proinnovation.com/Mexipedium xerophyticum characteristics and culture.html

hello, this page (server) isn't responding tonight. is it a local computer that's turned off?

 

[SlipperFan]

hello, this page (server) isn't responding tonight. is it a local computer that's turned off?

I just had problems, also, not just with this forum -- must be the internet.

 

[John M]

I can't make the link work either. :sob:

Being so close to the border, I have access to all kinds of terra cotta pot for cheap.

What border? What country? Please put your general location of where you are in the world, in your profile. Thanks!

 

[keithrs]

I'm in San Diego, Ca..... Baja Mexico boarder.