Hey Gardening & Landscaping SE, happy to be a new member! I am concerned for my cactus shoots and hope you are willing to help me out.
Short version: My 3,5 months old cactus shoots are starting to droop and some are turning a dull olive color (the two farthest away from the camera). The drooping is not visible in the photo as I have moved soil around the base to make them stand straight. Should I be worried?
Details: This is my first time trying to propagate Echinopsis pachanoi (also known as Trichocereus pachanoi or San Pedro) from seed. I planted the seeds in a metal tray with 3 cm deep soil consisting of cactus potting mix, perlite and sand. For the first 3 months I kept the tray in a plastic bag to retain moisture. One month before opening the bag, I moved the cacti from a dimly sunlit window sill to a lighting fixture with three 18 W fluorescent lights. The tray started out 35 cm below the light source, but a week after removing the bag I noticed the shoots were rather pale, so I moved them to 20 cm below the lights. The cacti gained a nice deep green color at first, but after a week some are starting to droop and turn an olive color that doesn't look all too healthy.