Since starting my orchid collection, I've always used traditional media such as orchid bark and sphagnum moss in either traditional glazed ceramic orchid pots or plastic net pots. There are a number of shortfalls and inconveniences to this method, the biggest of which is the investment of both time and money required to replace the media every one to two years as it breaks down. To combat this and the need to frequently water when using traditional media, Ray Barkalow developed a culture method called semi-hydroponics. For more about Ray or for much more in-depth information on semi-hydroponics, check out his website at https://firstrays.com/.
I was first introduced to semi-hydroponics by a few of the YouTube channels I watch such as Astrid, Michael's Orchids, and MissOrchidGirl. To be honest, my initial reaction was that it was unsightly and unneccesarily complicated. As my collection grew, however, I started seeing the value in media that was reuseable and that wouldn't break down.
Semi-hydroponics works by using LECA (lightweight expanded clay aggregate) in a container with a reservoir at the bottom. The LECA wicks a nutrient solution up through the container but, being more-or-less spherical, they leave a lot of space for air. Because most orchids are epiphytes (that is, they grow on other plants such as trees), they require a balance of moisture and air to their roots. Not enough of one or the other and they'll perish. The reservoir is made by placing two ~1/4 inch drainage holes on the side of a water-proof container a certain height from the bottom. The container is then partially filled with LECA, the orchid is placed with its roots in the container, more LECA is added to top off the container, and then water or a nutrient solution is added to the container up to the drainage holes. Once a week or so, water is flushed through the pot and out the drainage holes to prevent salt build-up and to remove anything else that might be in the container and then the reservoir is topped off with nutrient solution. And, for the most part, that's it. There is no need to repot the plant until it outgrows the container and there is no need to replace the LECA. The moisture level in the container is clearly visible as are, eventually, the roots so there is never any need to poke your finger into the media to find out if it is time to water or dig out the plant to determine its health.
As awesome as semi-hydroponics is, it isn't for every orchid or every orchid grower. It is good for most epiphytic or lithophytic orchids. It isn't suitable for terrestrial orchids for the most part, because it keeps the roots too airy, or for some vandaceous orchids that do better with bare roots. Ray actually has an article on his site called “Will It Grow In Semi-Hydroponics?" all about what can and cannot be grown in semi-hydro as well as a section of example photos of various orchids being culture this way.
After a lot of consideration, I decided semi-hydroponics was the way to go for me. Michael tends to use glass vases and other glass containers that he drills drainage holes into with diamond-tipped drill bits. MissOrchid girl uses a soldering iron to poke holes through decorative plastic flower pots. Astrid uses a variety of containers like plastic cups and deli containers. Ray himself sold premade semi-hydro pots that looked like deli containers with drainage holes. I decided to go hillbilly-chic and use mason jars with Hydroton brand LECA. My drill, however, had other plans and crapped out on me before I got many of the drainage holes finished. So, instead, I ordered a bulk pack of 32 oz plastic deli containers and poked holes into them with my cheap little soldering iron. For the nutrient solution, I've started with rePotme's granular MSU formula and I plan on rotating between that, Dyna-Gro Orchid-Pro, and Growth Technology Orchid Focus GROW.
As of now, almost my entire collection has been converted. I'm waiting on another order of LECA, more deli containers, and for a few plants to finish flowering before I convert the rest of them. The only orchids I don't plan on converting are my Calanthe rubens, my Vanilla planifolia, and my Vandas. I'm looking forward to seeing how my collection takes to semi-hydro and if it really works out best for me. I also grow some epiphytic myrmecophytes, bladderworts, and Nepenthes that I might consider experimenting with in semi-hydro at some point if it works out.