Might be a bit late for those but you could try Chinese greens which are a bit more tolerant of heat at the end of a growing cycle. Kailaaan (Chinese brocoli) is particularly valuable in Spring since you eat the flowers shoots so bolting isn't a problem.
I hope you gave those chickens a good talking to.
I would surely try again. Of course, if you have a very hot spring- they will probably bolt. But then, you could always feed it to the chickens! Nothing ventured, nothing gained.... Good luck!