Hello,

I am very new to growing cactus and would greatly appreciate a lesson with the issue I'm having.

These are pilosocereus seedlings (mixed species) planted from seed on 04/15/2015 using a bag method. I removed them from their bags starting on June 1, opening the bags a bit every couple days. Then on June 6, I removed them from their bags completely.

They are grown under HTG T5 flourescent lights placed 9 inches from the seedlings.

Here is a pic on June 6th:

And here is a pic on June 9th (today):

Are they getting sunburnt, dehydrated, both, or other...(or something else)?

Also, please correct me if I am making any beginner mistakes. Thanks!