Certified GKH Gardening Expert
They might be getting too much light! They will want quite a bit of shade, and no direct light as the temperatures warm up.
Make sure that the soil does not retain water for more than just a couple of days, as they need high airflow to the root zone. This can be achieved with a cactus mix, or cactus and orchid mix, together.
Here is an article that will help you to care for them: