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Re: [Aroid-l] Re: potting mix

Hi Ken,

Well, as you know I use only pine bark and perlite anymore. It is interesting about the pine bark comment earlier. You can surely tell where people live almost by how they talk about pine bark. Here in the north it is a non-starter to get any little fungi growing on top of your potting mix containing pine bark unless something is really wrong, but I know that the Frittilaria growers out in Oregon (Jane McGary) despise it because it causes their Frits to rot! The Frit growers in Philadelphia (John Lonsdale Edgewood Gardens) at have no problem at all wth pine bark. I imagine the humidity down south causes the same problems.

I have also found that any peat based product is a guarantee for rot in my climate. We are simply too cool in the summer with too much rain here in Pittsburgh. I've read that we get the second highest rainfall for any major metropolitan area in the U.S. and I can believe it!! I should say that I do not have a greenhouse so that very much limits my possibilities in terms of restricting water. I could not agree more with Derek's comments about watering as anyone that grows bonsai knows the Japanese take watering of these plants very seriously. Unfortunately, for those of us who grow our collections outside in the elements it is usually not me that does the watering but good ol' mom aka mother nature :o)

I have tried a different mix for my titanum, hewitii, decus-silvae, gigas and a few others recently that stay inside all year (Dracontium also). I use turface (this is high fired clay and so is very, very porous but holds water in the pores much like the high fired clay pellets that you use for hydroponic growing) mixed with the pine bark and charcoal (roughly 2:2:1). While I have only used this for approximately 2 years it seems to work well and I have not lost any to rot as of yet (knock on wood). I tried this because it is what I use for my bonsai collection for the past 15 years and the people at Phipps conservatory use it for their titanum and bonsai as well. You can buy turface by the pallet full also, but my needs are no where near that great!!

I think it is very important when considering a potting mix to look at where you grow and your climate and or greenhouse conditions. I just do not think that what someone uses in Miami or Tuscon will work for me here in Pittsburgh without some modification. Our climates are soooooo different that it is hard to extrapolate from one to the other. Of course, if they use a GH where the only water is from a well-monitored hose then all bets are off. There is nothing quite like 25 out of 30 days with rain and highs in the high 70s to low 80s (F) (the summers of 2003 and 2004) to make you appreciate drainage and rot in a whole new way!!!

Unfortunately, I really think that like most things in life it is trial-and-error coupled with listening hard and long to your mentors (I've e-mailed many of you with questions like this) until you think that you have it right and then your favorite plant gets kicked over by the kids anyway :o)

Good luck, Ken,


Gibsonia, PA (outside of Pittsburgh)
zone 6a (with a nice white covering of cold, fluffy stuff on the ground)

----- Original Message ----- From: "Ken Mosher" <ken@spatulacity.com>
To: "Aroid list" <aroid-l@gizmoworks.com>
Sent: Saturday, December 17, 2005 9:27 PM
Subject: [Aroid-l] Re: potting mix

MJ and Hermine,

I will post my results, but it will take at least one year, if successful, or more if I have to try again. In the meantime we can all benefit from the advice that's flowing back to us now.

MJ, our problem is a very bad one because of the high rot danger. It must be cured!

I didn't know that Fafard would do a custom mix. 5 or 6 cubic yards is a lot to me but it's one scoop to them!

Hermine, I had thought of acquiring a cement mixer to ease the mixing chore, but I didn't want to endure all the dust and I have no place to keep the darned thing. I mix all my cactus soil by hand and sometimes the dust is awful. Can't really wet it if I need it right away because you don't introduce damaged cactus roots to moisture unless you want increased risk of dead plants.

Scott Hyndman said something that alarmed me, that coir rots faster than peat?! If that's really true then a lot of us cactus guys better stop using it. That's our big complaint about peat is the rotting. Coir's been marketed heavily to the cactus world.


MJ Hatfield wrote:
Hi Ken,

Your problem with potting mix is the same as mine, except I grow in the winter year round and my greenhouse is ½ the size of yours. Top 2” dry, bottom wet. Over water more than under water. Rot. Work full time. Water by hand (too much lime and minerals in the water). This has been my worst year ever. Very sad. Please be sure and post what you find out. I need to do something.

MJ Hatfield

Middle of Iowa
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