Agree whole-heartedly!
Illustrates the point a seem to always bring up,
one size doesn't fit all,
so even amongst the few "groups" we designate of H.L./L.L. & Intermediate,
each plant will have its own unique preferences for temperature, humidity, lighting, etc.
So not all Highlanders want exactly the same conditions... hence one of the reasons that
one plant may be doing better than another, even though they are from the came "group".
As mentioned also, some plants grow faster than others, or have their own strong points too.
It is for this reason that actually growing plants and learning their language & what they are telling you they need, is the best way to master the hobby. (Like oh! my leaves seem anemic...! I need light, food, cooler or warmer temps, etc.)
Without knowing someone else's conditions, (like lights, temps, efforts at humidity, etc.) how thcan others hope to guess what the causes of the problems are? Especially if we have to guess what the conditions are too!
And I agree that the lighting could be boosted a bit, although the middle plant seems to be greener than previous leaves on it... likely new plants (less than 3 months old) or new conditions. As far as humidity, the plant pots, leaves and trays look bone dry to me!
(See how we have to think like Sherlock Holmes in order to figure out the conditions too, as they weren't provided. This is so common for so many people to do here!
Indeed, at least a picture was provided this time, so we are ahead of the game compared to most!
By the way, don't people read up on plants & how to care for them... if not before, but at least right after purchasing them? Especially expensive ones!
Well again, good luck. Swords & others have given a lot of good info. Bottom line is, you can't grow plants well, if you don't give them the conditions they want & need. With many plants, close is not good enough! They need what they need!