If you ever talk with a grower who says "I've never had a lockout" - keep on walking because that person is a liar! LOL!
Lockouts require flushing to fix... and a flush is when you run 3x the pots volume of pH'd water through it - so if you're growing in a 3 gallon pot, you'd want to run 9 gallons of water through it. Into that last gallon, put your nutes but at 1/2 strength... BUT before you do that, figure out how and why the lockout occurred.. was it because nitrogen levels became excessive? Then you're going to want to cut the nitrogen by MORE than 1/2 when you put the nutes in at the end of your flush and probably keep them at that level going forward. Was it because the pH was off? Then you have to make sure you ALWAYS check the pH of what you're giving your ladies whether it's plain water or water and nutes...
Once you've done a flush, you need to (obviously) let her dry out completely before giving anything more.... but that's it in a nutshell... I pity the folks growing in 25gallon pots outside, let me tell you!! LOL!
Good luck...