>Any opinions on how much damage a one night low will cause?
Some folks seem to do better, but my experience isn't good. Usually lots of damage, especially when there is heavy hoar frost. I see blasted buds emerging on some TBs from the one we've had earlier. Now the latest forecast is a freeze tonight with some spots dropping to the mid 20sF and another freeze tomorrow night. That's following a day of near 90F yesterday. It's an abysmal year. Only two small spring rains and some of the little green that provoked got damaged by the freeze, especially down in the river bottom. Relentless wind. Gusting over 30mph again today, only from the north. Tonight when wind would allay the freeze damage, it will probably die. Locally the wind and lack of rain are the major topic of local conversations. I'm frankly glad so many iris are not blooming due to the drought. It would more than likely be wasted effort. I hope you come out better. Maybe medians are more cold resistant?
Texas Zone 7b, USA