Dracula not growing

[Subrosa]

I can't speak to those particular species, but too high a temperature and not enough humidity are likely causes. I have 2 species that are currently outside in our summer heat and humidity. Luckily (for my plants anyway!) here in The mid Atlantic region extreme heat is usually accompanied by high humidity. And they do get night time drops of 20-25 degrees F. My anthracina has just about stopped growing, but the soennemarkii is growing steadily. The new leaves aren't as large as those it grew in cooler conditions, but it's growing ok. If you could arrange for a greater temp drop at night it certainly wouldn't hurt.