Mine was when I had a huge Critical Kush plant with at least 100 bud sites in coco ready to go into flower or become a mother. I mixed a gallon of RO water with nutes and balanced out the PH which was real low. Problem was, both the bleach drops and PH up drops were in similar brown dropper bottles and the black marker labels had worn off. I thought I was adding PH up to the mix but it was bleach. Probably added 25 drops or so to the gallon trying to get the PH to 6.0. Plant withered up and was toast within a week. Didn't realize what I had done until it was too late. Let's hear about your worst strainwreck.
Used gh ph down instead of bloom for a feed a couple years back. Color blind mf'er that I am. FYI...Lucas formula is shit with 5ml micro, 10ml ph down. Didn't kill them, but wounded them badly enough to drop yield by 25-30%. Forgot how much that sucked!
ooo I got one. Years ago I was growing in a garage that was split in 2. 1/2 was the grow room and 1/2 was just uninsulated garage space. Well it was way below freezing out, and in the non-grow half of the garage...probably about 10 degrees F(-12C). Well I noticed a few banana flowers on a new strain I was running, about 9-10 big plants that were about 3 weeks into flower. I pulled the plants and put them in the other half of the garage. I called a friend and asked if he wanted to finish them out, he was super excited and said he'd grab them tomorrow. I think - 'ok cool I'll just put them back into flower til tomorrow'. I opened the door to the other room (only about 5-10 minutes had passed) ..to my horror, all the plants were completely withered and dead...that quick. I never would have guessed that would happen so quick. I had to call my friend and give him the bad news ----------- **oo I got another one. When I was young and on my first real indoor grow. I was about 5 weeks into flower, plants were small but looking great at the time(my first indoor grow that made it to flowering). I think...hmm I want to add some CO2 to make the buds bigger, cuz I read that in high times. CO2 = bigger buds. So I grab the fire extinguisher, thinking that it's pure CO2. I thought I was so smart...I blasted those plants with what turned out to be a dry chemical fire extinguisher. Completely covering my little plants in a yellow powder....and my floor, walls, bed, dresser, table, myself..pretty much everything in my room had a fine yellow powder on it. Plants were ruined. I threw them out and spent the rest of the night cleaning up that damned yellow dust.
I was growing commercially (not my personal fuck up but it was my responsibility) and I had one of my employees see a herm and not take it out. He said he saw it but lost it and forgot. Well you know what happened. Seeded a whole room of 900 plants! All went to our extraction lab. Recently I squeezed my rockwool cubes to get excess water out when taking clones and I guess you are not supposed to do that only 10% rooted and I had to take clones from plants 2 weeks in flower and now I have to revert them and it's taking forever!