Question
QUESTION: Hello Jeff & Jacob!!..

I'm starting again with VFT from seeds.. but this time to be more precise I've bought an EC meter and a Ph meter...

I've no sowed the seeds yet since I had the idea of testing the soil (50% peat moss 50% perlite)..


For my surprise the water falling down the containers and crossing the soil measures the following:

Ph: 4 - 5 (It's ok, I'm not impressed for this value)

EC: 0,5 - 1,0 mS (MILI siemens) depending of the container tested.

I think that 1,0 ms is a lot for CPs and more yet for VFT !!! (?)


Normal plants that I grow measures 1,0 - 2,0... (?)

That value so high explain why a lot of algae and moss grew inside the containers and VFT died last time I tried..

I can do a water-wash (I got rainwater, (0,01 - 0,02 mS))

that is something like 10 ppm, that's really fine since I've read that for CPs 50 ppm (0,08mS) it's ok.

I did some rain-water-washing with some containers but there are 2 problems and that is why I ask help..

1st problem, I don't know when to STOP washing... Some containers now measures something like 0,25 mS.. I "think" that it's too much yet but I don't really know..

So the first question is: how much (EC) water coming from bottom of the containers should measure? .. which is the highest value? .. 0,08 mS ?? (0,08mS = 50ppm)


The second problem is that collected rainwater measures 6,9 (ph).. and washing raises Ph to heaven..

I think I can use some acid to correct ph of water for washing.. but I don't know which acid.. I've tested vinegar (water for washing @ ph 3,8 - EC 0,1 mS (Because vinegar dilluted raises pure rainwater EC from 0,01 - 0,02 to 0,1)) and I concluded that vinegar is too weak, because ph of water falling down the containers continues raising (6,4 @ this time)..  I hope you have understood.. I don't know if I can explain  my "reality" in a "writen form" and worst (to me), in english..
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A brief summary of all writen above should be:

How much (mS) should measure water coming from a tray with CP SOIL ???

and.. if I want to correct pH for water that I use for watering my plants.. WHICH ACID should I use??..

thank you very much, and excuse me for writing this "long question"..



ANSWER: Hi Jose,

Wow!  To grow Venus flytrap seeds, the trouble you are going through is a little bit like renting a flamethrower to light the candles on a birthday cake. :)

The information you've collected is very interesting, but my first question, is what is your source of peat moss?  Here in the U.S. I always tell people to buy peat moss in the bales since it is 100% Canadian sphagnum peat moss and nothing else.  Smaller bags are mostly marketed by Scott's/Miracle-gro, and almost always have fertilizer in them.  That would cause the algae problem you are experiencing.  Even good quality peat can get some algae growth on it, however, so a partial sterilization of the media surface can help.  Products such as Physan 20 or Consan 20 are quanternary ammonium compounds normally used in disinfectants.  In the correct dosage, they make a great preventive spray to kill algal and fungal spores on soil media.  If you can't find peat moss bales, consider using long-fiber sphagnum moss, or something inert such as rockwool.

Don't worry too much about measuring the total dissolved solids coming from the media since the tannins in peat moss can add to this figure.  The tannins are good for cp.

Don't try to acidify water.  This is one of those measures that might give a drop of good, yet can be very disasterous if you add too much.  If your peat moss is giving an alkaline measurement, it means dolomite lime has been added to it.  Again, the problem is the type/brand of peat moss.  Better to find a different media.

Normal pH in sphagnum bogs is usually around 5.  You wouldn't want to be lower than that.  The 3.8 measurement you got from the vinegar would kill most plants.

With water don't worry about the pH.  You want the total dissolved solids to be 50ppm or less.  If it's more, then you need to consider getting a reverse osmosis unit for your tap water, or take a look at how you are collecting your rainwater.  It's almost unheard of in this era of acid rain for the pH of rainwater to be alkaline.  Something the water is passing over is raising the pH.  As I mentioned above, acidifying the water is dangerous.  You just want to get that TDS low.

Good Growing!

Jeff Dallas
Sarracenia Northwest
http://www.cobraplant.com

---------- FOLLOW-UP ----------

QUESTION: Hi Jeff!!

The peat moss that I bought is the only available in the market here, It's imported by a local seller and I don't know where it comes from... it has a good pH as I told you but 1 mS/cm (EC) seems to be too much..

I've seen on the internet some peat moss analysis, for example:

http://www.premierhort.com/eProMix/Horticulture/TechnicalData/pdf/TD2-PRO-MOSS-H

The value of 0,07 - 0,3 mmhos/cm (ms/cm) in this analysis definitely is lower than 1.0 from my analysis... I would be very happy if my peat measures something like that.. I think that peat moss here is fertilized or simply it's a bad quality.

There are no choice, this country is not USA :) .. nobody sells live sphagnum, there are no other peat mosses.. that's why I'm very worried..

I have more than 600 VFT seeds, and 300 drosera seeds... and I want to do the best this time...

and about rainwater.. I think you didn't understand.. my rainwater measures 0,01 - 0,02 mS/cm .. That's something like 6 - 13 ppm .. I believe that rainwater is excelent..

So.. I have two options at this time.. I can sow the seeds on the media "as is" (PH=4, EC=1,0mS/cm) or I can do a rainwater-washing of the soil.. that lowers EC to safe levels ( < 0,3mS/cm ) as shown in the analysis of good quality peat mosses on internet.

The only problem with that is that washing with pure (and neutral ph) rainwater raises the ph to 6,5 and may be more...

I think it's too much alkaline but if I don't wash, the soil "as is" seems to be "strong fertilized"....

I've discovered why NOBODY grow CPs in this country... :@

thank you very much for your help!!

Answer
Hi Jose,

If your peat starts out with a nice low pH then rises after washing, that is happening because of tannic acid being washed out.  It does sound like your rainwater is just fine.  Your peat moss may be ok also.  The link is from a company in Canada who's peat moss we've used.  It is fine.

Here's what I would suggest trying.  Boil your rainwater before using it, and sterilize your peat moss also by putting it in a big pot with your rainwater and bring it to a boil for a few minutes.  This will help remove any fertilizer present, and kill any algal spores that seem to be plaguing you.  After that water only with your boiled water.  By doing this you should really slow down algae growth.  Try using this sterilized peat with a small quantity of seeds and see what happens.  Let me know how it goes.


Good Growing!

Jeff Dallas
Sarracenia Northwest
http://www.cobraplant.com