How do i keep my Araucaria heterophylla plant alive and health indoor in a dry envionment?

Question

Leaves were dark green, but are getting lighter green

Answer 1

Hummm, it sounds like a nutrient deficiency from your description. If it was just the humidity, then you would see the leaf get thin/papery and browned out from dessication. If you are already watering the plant correctly you need to occasionally fertilize the plant (light green usually indicates nitrogen deficiency, yellow/chlorosis usually indicates iron deficiency). Too much fertilizer is bad too, you'll get a gangly plant and weak growth . You should mist the plant with water from a sprayer every other day or so depending on how dry your house is.