Thanks very much, Dave!
Laying it out that way helps me see the period during which 4-5 degrees of extra frost protection might stretch my season by six weeks. And if I knew I could reliably maintain 10 degrees of overnight warmth ... twelve weeks? That's getting to be year-round growing.
It always puzzles me why people would go by a "50%" date. I'm not so ambitious as to WANT a 50% likelihood that everything I plant will freeze to death. I might gamble on a 30% probability of "killing them all" , IF I'm sure I'll have time to try again that season.
