Marin Orchid Society

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Take Advantage of Mary Ann’s Experience

Over the summer and fall, I repotted all of my orchids … over 400 (I lost count).  Our editor asked me to share my experiences because I am using the redwood bark that Tom Perlite discussed.

For those who did not know, I was an avid fan of a potting mix names Aussie Gold and I used it almost exclusively. (I sometimes I used sphagnum moss and still use it.) While I had amazing results using Aussie Gold when I grew indoors, I ran into problems growing in my greenhouse. My fault really; I just could not stop watering every week! in the higher humidity of my greenhouse, the poor roots were kept just a little too wet. Not so wet that they did not survive, but wet enough that they did not thrive. To remedy the situation, I repotted almost everything (except for those who loved that moisture) in Rexius Bark, medium or small, depending on the type of roots. Even all my bare-root Vandaceous orchids went into bark.

I have also been experimenting with gorilla hair (shredded redwood bark that can be cheaply bought at any landscape company). I really like it; so far it is working well. I have a couple of small Catts, a couple of Oncidiums, and a couple of Bulbos in the stuff. All are doing okay. We’ll see what summer brings. I don’t want to have to water more than once or twice a week, so I may go back to moss for some; time will tell and I will report the results later in the growing season.

Because I was worried about the orchids being too dry compared to their previous medium, I added diatomite to the bark and to the gorilla hair. (I also added a little charcoal.) The neat thing about the diatomite is that the water it holds evaporates out of it s-l-o-w-l-y without keeping a whole lot of wet at the roots. I used roughly a 1 to 5 mix of diatomite to bark. For the gorilla hair, I lined the bottom of the pot with diatomite, depending on how much moisture that orchid likes.

I am happy to report that all my hard work (and it really was, although a labor of love) really pleased “the girls” as I like to call them! The Catts have thanked me from week one; they seemed brighter and stood up better and I now have new growth and plants flowering that would not before. The Vandas are also spiking and flowering well: no more blasting (as they were doing before being repotted). The Oncidiums seem to be doing okay, although I am worried that they may need more than weekly watering in the summer. If this turns out to be the case, I am unwilling to do this and they may need to into moss.

For those who want to know, you can buy enough Rexius bark at the Marin Orchid Society meetings to report a few plants. This mix contains charcoal and perlite. If you need to replant a lot of orchids, I bought huge bags of Rexius bark from Jim and Kris Foster of the Sonoma Orchid Society. The diatomite can found online.

Happy repotting next season!