I forget to mention...this is in a ten gallon aquarium tank!

Dendrobiums will rot in potting soil, in that particular setting! Also, is this a 150W CFL, or is it a 150 incandescent equivalent?

Keep us posted!

Your dendrobiums will die because, #1 - they don't grow in soil. #2 - Your lighting is weak. #3 - The aquarium will be too moist.

Try planting them in clay pots with bark and putting them in a very bright window. You will be surprised how well they do. Hard can dendrobiums are among the easiest of plants to grow.

They're under a CFL light. Will the Dendrobiums that i kept in the original pot have a chance in this environment. I have a screen top on the aquarium - will it still be to humid for them?

Much Thanks.

Sorry to say, but the African violet will also rot in that setting. Moisture holding potting soil is best used in a situation where you might experience droughts or periodic dry conditions, usually in your garden. I personally would never use it for houseplants, but it was great for container gardening in my concrete yard that gets baked by full sun exposure and 95 degree weather in the summertime. In a terrarium, which is meant to be humid generally, I think that both the dends and the African violet will rot pretty quickly. The screen top will hold in less humidity but will not help that much with preventing rot at the soil level.

Additionally, it's hard to answer whether or not that CFL is enough light until you can say if it is a 150W CFL, or a 150W incandescent equivalent. It's a huge difference in light levels between the two. A 40W CFL is a 150W incandescent equivalent, roughly, whereas a 150W CFL is a 500-600W incandescent equivalent.

Not trying to be a downer, but I don't feel like this situation works as is. I grow orchids in a terrarium, but they are almost all bare root, mounted on cork or a wood plaque, and require less light than dends do. I do not have soil in my terrarium, but a mix of bark, tree fern fiber, and coco fiber, and nothing is planted directly in it. Just curious, is there a reason you want to grow them in a terrarium, instead of on a windowsill? They're not the first type I think of when I think of terrarium orchids.

Hope this didn't sound harsh, but I want you to be able to successfully grow your orchids, and to help you figure out a solution that will work well for you : )

Harsh? No not at all. I'm here to learn and this post helps me immensely.

Not sure why i used the moisture retentive soil...your explanation makes perfect sense. The light is a CFL 150Watt. I just removed the dends that were buried in a pot - they were soaking wet even though the original bark was left in the pot. The edges of the leaves were starting to brown. Hopefully they can survive in a window. I have a nice window to grow them in but there are trees that I would not want to get rid of shading the window most days. This time of year i'm okay as the tree is deciduous. That is partly the reason i tried them in a terrarium.

What types of orchids do you grow in a terrarium? Perhaps I'll go to mosses and ferns for it as so many sites suggest. I just need something in my home office for meditative purposes.

Thanks so much.

Sorry, I never answered your question. I primarily grow Angraecoid orchids in my terrarium, and of those, most are Aerangis species. They are fun for me to grow because they are small and have lovely white flowers, but they have some specific needs. Humidity and good air circulation are really important for these guys.

But I also grow a Phalaenopsis equestris in another terrarium, and it is pretty happy there. I used to have a fan in that terrarium too, but everything dried out much too fast, so I removed it, and nothing seems to mind. There is also a Cattleya luteola in there, as well as a Phalaenopsis stuartiana and a Streptocarpus hybrid (not an orchid, but related to African violets). The only one that is in a pot is the Streptocarpus; everything else is mounted on cork. I put Hydroton at the bottom, a layer of charcoal and bark on top of that, and a mix of tree fern fiber and coco fiber on top of the bark and charcoal. But nothing is planted in it. There used to be a selaginella (club moss) in there, but it dried out and died during the time I had the fan in the terrarium.

I would say that you could grow some nice things in the terrarium with a different mix, and different orchids. Or head over to the terrarium forum for some ideas. I haven't been there in a while because it didn't seem that active at the time, but it was fun to browse or search the forum, and to see what other people had set up.

How are the Dends doing in the window?

I also grow jewel orchids in terrariums, but there are a couple of key things that need to be kept in mind... it's great you have a drainage layer, they are a must have. Above the drainage layer needs to be a substrate that does NOT hold moisture - because you'll have humdity coming from below you actually want the water to run right through and not sit on the plant roots. I use a mix similar to what quinnfyre mentioned. The water in the drainage layer must not ever get deep enough to actually come in contact with the substrate.

I also start all my terrarium plants from cuttings, as they are starting lost of new growth (roots and leaves) and they quickly adapt to new conditions since the new growth is adapted to the conditions it grows in. I do this with both gesneriads (including AVs), as well as jewel orchids which tend to be trailing plants and root from any node. Start AVs by dropping a leaf in the tank, rather than the whole plant you bought from the store which is hardened off to be a houseplant.

Just a note as well... mosses and ferns can be some of the more challenging terrarium subjects I found! Ferns like air movement like most orchids do.