Quote:
Originally Posted by totziens  I have seen a friend who dumps her narrow leaf fern in a pot at the balcony without any fan or chiller...and she had no problem at all. |
If her ferns are getting natural light (from Malaysian tropics), I'll bet the daylength for her plants is at least 12 hr/day.
I would forgot about nutrient deficiencies. By adding more fertilizers (especially iron), you're more likely to kill them with metal toxicity than help them.
I'd also rule out temperature. Kasselmann's book shows that the temperature optimum for Java fern is 20-28C with a maximum of 30C (86F). They can take the heat!