One of the sites where disa uniflora can be found is on Table mountain (Cape Town, South Africa). They grow on wet slopes and on the edges of rivers/streams and aqueducts on the mountain. They like to grow in clumps and can make spectacular flowering displays. Blooming typically happens in Feb, the hottest month of the year.
Here are some photos from a recent trip to see the blooms. One of the aqueducts where they typically thrive seems to have had some maintenance done on it resulting in some plant losses

but hopefully they'll bounce back. This year the best flower show was in previously un-spectacular areas.