Keep a fan on them and they should be fine. I have mine in a greenhouse that can get in the upper 80's in the summer but there is always plenty of air movement and I have never had any problems at all. I keep mine in tubs with wire tops so there is plenty of air circulation and behing shade cloth. I have even seen it get in the low 90's at times and once again never had a problem and production has been fine. I think air circulation is key.