How to tell if plants are overcrowded

Do you mean like if they are too close together?

PM will set in overcrowded rooms,you will also get more vertical growth not horizontal.

How close are your plants, or post a pic.

In my garden... I leave enough room for my hand to pass horizontally in between plants ....without touchin the leaves

i don't let fans give more than half a leaf of coverage from 1 plant to the next
they touch but only by an inch or 3

Shit my girls are all up in eachothers space! I feel so sloppy now...but I'm clean I swear

It is a sog grow. The leaves sometimes touch the buds on the adjacent plants. They are more crowded now than in the pic.

hay mate did u not veg at all ? wat size were they wen they went to 12 /12 looks good