potting mixes

relative newbie, pros and cons of organic verse inorganic potting mixes, time to start repotting some of my first Phals, up to 180 plants now i can see repotting is going to be an expensive proposition, would inorganics keep me from having to repot, right now i use msu fertilizer, would i have to change fertilizer, would i still use coarse mix for bigger roots, medium for medium rooots and fine for fine roots, still on the steep side of the learning curve, thanks john lapointe

Choice of media is a choice based on lot of factors ( watering frequency, relative humidity, your grow area micro climate). Choice of media just one the factors in orchid growing. Given that you have about 180 plants, you can try a similar looking phals may be 2-3 in organic and inorganic and observe them and then decide what works in your environment.

Coming to coarse, medium and fine media. I use same media for all my Orchids and they seem to be doing ok.

Concerning the fertilizer, it really doesn't matter much, as the plants get very little nutritional value from organic potting media - unless, of course, it is decomposing, in which case, you'll want to change it anyway.

There are two extremes in potting media selection: 1) use the same one for everything, and adjust your watering for each individual or small groups of plants with similar needs, or 2) adjust the medium, customizing it as needed, so you can water everything at once. And of course, there's any number of variations in between.

Concerning the use of inorganic media, while they will require less frequent replacement, none are truly "permanent", as they do absorb plant wasters and fertilizer minerals, eventually concentrating them to a degree of toxicity. The use of pure water, low rates of fertilizer addition, and frequent, thorough flushing can extend that tremendously.

I have evolved over these many years to Raybark's #2: "adjust the medium, customizing it as needed so you can water everything at once." My evolution comes from getting different orchids, after I got over buying and rescuing big box store cast offs like Phalaenopsis. Different orchids seemed to require different potting style.

For Phalenopsis, I have half of my plants in New Zealand Sphagnum Moss and the other half are in bark mix. In either case I pot them in clear plastic pots with slits allowing for air exchange and moisture evaporation. The plants in moss are not watered as often as those plants in bark. I live in Fort Wayne, Indiana so in the winter time it is critical that my plants have good air circulation, good relative humidity, and warm fresh air. In the Summer, when these plants go outside I have to pay close attention to moss potted plants as if it rains too often, these plants can suffocate with too wet moss and not enough air/dry time. The bark mixed plants--no worries.

My bark mix: Orchiata medium size, equal sized sponge rock or grow stones, charcoal, and LECA.

With the amount of orchids I was getting I went to mounting as many of them as I could, cuts back on the amount of media and time to repot every 2 years. Yes I have to water my mounted plants more often but that was one of the reasons why I put an irrigation system in.

For those I do repot every 2 years I make my own media mix to fit the requirements for all of them.