About a year ago I got a piece of Stanhopea tigrina var. nigro-violacea 'Predator' FCC/AOS from our Society's auction table. The donor said she didn't have time to water it often enough, and it didn't grow well for her. Nobody bid on it. I offered the minimum bid, which I have since realized was far too low for this very valuable plant that has never been mericloned.
It had seven small pseudobulbs, a few with leaves. All the roots had been cut off right at the bases of the pseudobulbs.
I don't have a lot of experience with this alliance.
There is a thread here by rbarata about his experiences growing Stanhopea wardii from bare-root pseudobulbs, and I learned a lot from him.
I knew it would only make new roots from new growth. I knew it would only grow during warm weather. I knew the tiny remaining root system would have trouble supporting the plant before then.
I set the plant into a low but wide glass candy dish on my kitchen windowsill, and set the base into a very shallow layer of water. I took it out almost daily to rinse off, and exchange the water, turning over and examining the plant carefully, top and bottom. I cleaned the dish regularly.
It sat there for months, dropping leaves one by one. As we went into winter it was leafless. I continued the care.
This spring I soaked the whole plant, monthly, for several hours, in KelpMax solution. In about April, when it was very warm, I turned it over, and saw the plant was beginning 7 tiny new sprouts. I didn't know how soon it would make roots, so I waited, keeping it wet in the candy dish.
After the first sprout began unfurling a leaf, but with no new root growth, I decided to pot it up. I lined a wire basket with decorative dry moss. I filled it with a mixture of extra large perlite and potting soil. I nestled the rootless pseudobulbs and backfilled with potting soil. I put it into bright shade in my humid sunroom, and kept the medium around the pseudobulbs always moist.
The first leaf matured. Then it began making a few roots.
Slowly over the summer 5 other growths have emerged. In the photo you can see the largest, oldest growth. There are three other growths with smaller leaves. One of them, in the lower left, has two leaves. And emerging below the oldest leaf are two other new growths.
I haven't seen the seventh growth yet, but I'm still hopeful.
Our society member also gave anybody who wanted a very small (and also rootless) division of another Stanhopea. I put my piece, with three pea-sized pseudobulbs, into a teak basket with long-fiber sphagnum moss. I kept it wet. In spring it began a new growth, but despite me keeping it wet, that growth died, and the pseudobulbs soon followed. I don't know why that happened.