[PhalPal]

Your leaves may be getting sunburned. Cyms like lots of direct light, not direct sun. They also like to be very crowded in their pots, very crowded. Move them out from any direct sun and water them more heavily during hot spells, never letting the media dry out completely. Humidity is the more so the enemy to cyms then heat; many experienced growers cannot grow them in Florida and other areas of the east coast. Our temps have been above 100 for several days but with low humidity, and my cyms are just grinning through it. I have them outside under a eucalyptus tree in the shade with indirect light and they do fine. I am sure some other geeks with higher humidity conditions can help you more, but for now move them out of the sun!