Does brighter light result in smaller leaves in climbing aroids? I have few plants which produce tiny leaves compared to the leaves they came under my care with. One thing they have in common is that they are all placed in SE windows and get direct sun for 2-3 hours in the first half of the day. Could that be the reason? If so, how could I place them best in order to encourage them to grow mature leaves?

Side info: they grow in moist media with bark and perlite and get a water soluble fertilizer 1-2 times per month. They grow really fast, but I'm concerned about the size of the new growth.

(Philodendron hastatum as an example)

I am not an expert in this. Bu I have read that climbing aroids are either positive or negative phototrophs. Positive phototrophs grow up and IN the light as much as possible and produce bigger and better leaves as they climb. Negative phototrophs climb more toward the interior of the tree they are climbing on, seeking some shade from the brightest light, until they reach high enough to come out into the sun fully. I don;t know which plants are which, I am sure among species its quite variable

Thank you very much, Gina. Well, it started growing much smaller leaves the moment I picked it up from the shop - and the first thing I did was placing it on a very bright window sill. So I will go ahead and assume that this phototroph is negative

Does it then mean that I shall place it in a shade some distance away from the light source? Or just in a shade next to the window?

I am not sure about P. hastatum. Did you research its natural environment?