All ours in the cold greenhouse have also gone curly this year. I wondered if I should have whitewashed the glass due to the heat. Had a lot of splits too due to panic watering. On hte bright side the Oxhearts, Rainbow, Banana Legs, Green Zebra, Abraham Lincoln and Costoluto I grew outside straight into the plot ( OK with some added horse manure and liquid feed weekly), have done brilliantly well with minimal curl on only 1 plant.