Plants I will never grow again

I do, have or would try any of those on the list so no vote from me!
Pak choi just bolts - seedling leaves, flower stalk, bam, dead, but giant vegetables of any sort probably top my list.

You need Joi Choi F1 in your life, it's the most bolt resistant pak choi I've grown, doesn't go to seed until mid-May from a February/March sowing. I've just planted some more in the ground to see how quickly they go to seed at this time of year.