Bletilla were my favorite garden weed in California (Zone 8b) where it was coming up anywhere that was shady and damp. I brought some with me to Reno and planted them last spring. They did great over the summer (afternoon shape, morning sun). I didn't mulch so am waiting impatiently to see how they survived the winter.
Maybe in warmer zones they need a lot of dug in compost and shade to grow. Mine were competing with baby tears and cyclamen. I don't understand why such a rampant grower is so expensive to buy. It's like Helleborus. They are weeds that cost $25 for a 1 gallon pot.
Good luck in your project. I know that when growers bring Bletilla to Orchid shows and sales, they are gone in an instant.
Also Stream Orchids. The native one, Epipactis gigantea. Rampant growers that sell out fast at shows.
Daisy