Growing orchids mounted on live trees.

[SG in CR]

I've been living here in Costa Rica for several years now and when I got here I was excited to be able to grow plants that were strictly houseplants back in Michigan outdoors. So I got some orchids from a nursery and mounted them on a rambutan tree behind the house. It seemed like it had just the right amount of shade, enough to keep them from frying in the sun in the dry season and not so much that they wouldn't get enough sun.
I got what looked like a couple hybrid dendrobiums, a spider orchid and a couple phals. I proceeded to tie large chucks of coconut husk to the branches and then mounting the orchids to that. I figured the coconut husk would help hold water and give the orchids something to grow their roots into.
Well, it didn't work so well and after a few years of remounting and coddling them, I think I've found some things out that I wish I had known back then. So maybe I can save other people from making the same mistakes.
1. Mounted orchids like to be firmly bound to a solid substrate. Mounting the orchids to the coconut husk worked out OK for a while but as it started to decompose the orchids started to do worse. I found that tying them directly to the branch tight enough so that the wind can't shift them around on it made a big difference. It didn't take long before they anchored themselves down solidly with new roots that clung to the bark like they were glued on. If it's an orchid that I think needs more moisture, then I tie some live moss on top of the roots so that they hold the moisture there. Eventually the moss will start growing and look more natural.
2. Don't let liquid fertilizer dry on the leaves. At first I was using an orchid fertilizer I brought back from the States and I would just spray the plants with it diluted to what the instructions said. The orchids didn't like this. Leaves and roots started to yellow and dry. I found that going back with a sprayer full of clean water before the fertilizer dried and spraying off the foliage made a big difference. I'm not sure how much the plants can absorb in 15-20 mins before I washed it off again, but they seemed to grow and bloom just fine.
I switched to a new method of fertilizing them now though. While visiting the Lancaster Gardens orchid house I noticed they were using slow release fertilizer pellets inside small mesh bags to fertilize the orchids. I started doing the same after I brought some Osmocote slow-release fertilizer back from the States and it seems to work great. Especially for my Gongora, they grew 3-4 new pbulbs from each of the previous year's.
3. Let your orchids go to seed if they get pollinated. I had a Brassia that was doing really well at first. And I kept trimming off the flowers if I seen they had gotten pollinated, figuring I would rather the plant spend it's energy growing and flowering. And so it did. It kept flowering till it was so spent that it died. Later talking to someone who had more experience than I, he told me that some orchids once they get pollinated are so determined to go to seed they'll kill themselves in the process of trying if never get to finish maturing the pod. Since then I've always allowed one pod per flower stem to mature if they get pollinated and the orchids still bloom every year. In fact two of my Gongora bloomed a couple months ago and are developing seed pods and now they going for a second run with new flower shoots coming out.
In any case, these are things that work for me growing mostly native orchids outdoors. I'm sure more experienced growers can correct me if I am making any false assumptions or giving bad advice.