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Potting soil for carnivorous plants

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I recently decided to give raising carnivorous plants another shot and found out quite a bit about the potting soil and other requirements. They do vary some between the different plant species but there are certain elements in them that are the same. I'm caring for Venus Fly Traps and a Sundew variety that should do OK in the same soil. So, that is the specific mix I went for. 

In the course of learning the "best practices" way of doing this I spoke to peat producers, professional plant growers, a couple botanists, sales people and several enthusiastic and helpful hobby growers. Everyone had an "I killed my plants story." and everyone had something interesting to add. 


 
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Step 1: The components and "tools"

Peat Moss- see below
Sand- See below
A large mixing bowl
A measuring cup of some sort- I used the bottom half of a glass soda bottle.  

Peat moss, specifically sphagnum peat. Not to be confused with green moss, long fibered peat or carpet moss, all of which can be found in bags calling them "peat moss". There are differences and they usually have negative effects. Almost all are not immediately evident and will only show up after weeks or months of seemingly healthy growth though some chemicals that are found in certain products may kill your plants very quickly. 

I used Uni-gro premium organic peat. It's distributed through L&L Nursery Products here in California. It doesn't state the source on the package so I called them. It's Canadian sphagnum peat that comes to them from a company in Alaska and is then packaged by L&L for resale. This is a good one for US growers. No chems, fertilzers, wetting agents, just peat moss. It was just a few dollars for a 4 quart bag. 

The other component I used was a very clean chemically inert black cover sand from Mosser Lee. Again, no chems, additives, fertilizers or anything else. It's cleaner than the washed sand recommended by more sources than any other component and it's non-leaching so you won't need to worry about mineral content over time. 

Distilled water. Yes, you need this to make the soil. Rain water will do but it is so easily contaminated you'll either need to control the harvesting process carefully or just go ahead and buy distilled water. This is not the same as bottled water and chlorine isn't the big offender, so setting a bucket of water out for 24 hours the way you might do for fish will not make it safe for your plants. Many bottled waters have salt added for taste. If you must, you could buy low sodium drinking water but it's a poor risk with distilled water easy to obtain. Soft water is not acceptable for the same reasons. While these things might not kill your plants right away, some will and all they will over time. Again, the salt in Bottled water added for flavor is negligible as a food additive but will accumulate over time and harm your plants.  

Notes on other materials:

Perlite or pulverized lava rock may be used in place of sand if it is additive free. Just make sure it doesn't have a fertilizer component like miracle grow and maybe call the producer and bug them about salt content as well. 

Coconut husk will work but requires several rounds of soaking to force out the small amounts of salt that are present in the coir. If you really want to use coconut fiber and have an extra month to process it there is information out there. Using it as is, out of the package, will likely kill your plants after a few months of watering when the salt finally starts to effect the roots.

I did not do a soil salinity test on any of the materials but did do a pH test on the final batch for the plants and based on direct information from the producers of the products was assured that there were no salt or chemical additives. 
Wow, thanks for the information on the brands and how to measure the volume ratios of the peat moss, esp that different types contain undesirable elements for flytraps. I was wondering; is that a real skull? If so, the acidity of the environment will leach minerals out of the skull into the soil. It's probably plastic, right?
Culturespy (author)  GossamerSails3 years ago
No, its a real skull. The bone is actually slightly base rather than acidic. The real contribution to the soil is potassium but with a whole bone rather than something like bone meal, it doesn't leech much. Though, it doesn't take much to killthose plants. I transplanted the ones in that terrarium to an apothecary jar about a month ago and gave them to a friend. I didn't include the skull. They are doing fine as far as I know but the bone was probably a bad idea and not something ill do again or suggest for such sensitive plants.
afridave3 years ago
But seriously,ive purchased a package that contains a variety of seeds for 5 diffrent carnivourous plants but have held back on planting them as the instructions about the soil are rather sophisticated and i dont want the plants to die so ive read this with great intrest and will research a bit further and only plant when i feel confident that i know whats too be done,thanks for the tutorial.
afridave3 years ago
Has anybody managed to cultivate a triffid yet?
Very nice! I have a copy of The Savage Garden, and it really is a helpful book.  Here's an article of when Peter D'Amato was on "Gardening by the Yard".  I can't find a video of it, but it was a good episode.
I find these plants to be fascinating, but with small children in the household I've put off getting any for fear someone would get hurt. My friends tell me I'm being silly, but I just don't know. Clearly you know quite a bit about this topic, so I'd really appreciate your opinion. Am I being an overly-protective parent, or is it reasonable to be concerned about the danger posed by these carnivorous plants?
Having spent a good deal of time around both small children and carnivorous plants (including giving presentations in science classes), I can say that there is only one caution I would advise: make sure the muscileginous "dew" from a Sundew plant does not get in your eye. It can sting, but flushing with water, like you would do for any other irritant, clears it right up (it is water soluble), with no lasting damage.

Other than that, there is no additional danger with carnivorous plants and children than you would find with any other plant.  If you're okay with a Poinsettia, you should be okay with CPs.

The same is true for pets.  I have known many dogs and cats that have lived harmoniously in homes with lots of carnivorous plants.

I have heard unconfirmed rumors that Sundew leaves have actually been used as an ingredient in salads.  Let's hope the leaves were free of insect carcasses!
Culturespy (author)  Mr. Potato Head3 years ago
I'm not aware that there is any danger from these plants unless you are a small insect. They don't sting or "bite" and while you'd want to confirm this, I don't recall reading anything about them being toxic. I would say it's wise to be concerned about any plant in your home, while as far as I know these are perfectly safe, many common house plants can be lethally poisonous if eaten. So, I'd say ask your retailer when you go to purchase them but carnivorous plants should be totally safe. They won't eat our children ;)
zennmaster3 years ago
BEAUTIFULLY done instructable!

A couple of things to keep in mind: The main purpose of the peat is to hold water, and the main purpose of the sand is to "open" the mix. The exact ratio isn't as important as maintaining a plentiful source of water for these thirsty plants.

Nicely done!
Culturespy (author)  zennmaster3 years ago
Thanks!
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