Whether or not broccoli is frost-tolerant depends on what kind of pre-conditioning it has gone through. It will be important to consider the conditions which broccoli is used to before determining whether or not it is truly frost resistant.

If a certain crop of broccoli is consistently exposed to fairly cold weather, it is likely that if the temperature drops significantly it will be able to survive.

Broccoli that is used to being in warm weather however will likely not survive should the temperature of the area drop below around 22 degrees because of the fact that it is not conditioned for such temperatures.