When does everyone cover their plants at night? I still have green peppers, tomatoes, cherry tomatoes, carrots, beets and onions in the ground and this week temps are looking to be in the low 40s at night, with some hefty winds too. I'm not too worried about the onions and carrots, but I don't want to lose anything else.
I don't cover many of my summer plants to extent the season. I have too many of them, for one thing, and by now I have pretty much gotten my fill, plus things like tomatoes aren't what they used to be. I cover my cold weather plants, after it starts getting below 25° regularly. And my rosemary gets covered below 20°.
I don't usually cover much of anything at this time of year either, I figure if it's over it's over! But, last spring I did find myself using some sheets for some things I didn't want to lose. I did that when the forecast was for anything from say 37 degrees to low 40's because it seemed like I was getting frost here and there at those temps.
I think freezing is more likely with calm, clear air and no wind; the kind of weather you get after a front moves through. If there is a cloud cover with breezes I think you're safer. Also, if your garden is in a lower lying area, as some of mine is, you might be in greater danger since cold air is heavier. If your plants are up against a building, you will probably be safer.
I agree it is not really worthwhile to cover tender plants at the end of the season -- the fruit quality is not very good and by this point I have certainly had my fill, as has the freezer and the canner.
The only thing I ever bother to cover is tomato plants. They often just have green tomatoes on them when frost approaches. Everything else is pretty well done by frost time.
When to cover? Listen to the local weather forecast. If it is supposed to get down into the 40s, best be thinking about covering. Also it always gets cold as a storm moves out in the autumn.
Gardening at 5000 feet elevation, zone 4/5 Northern Utah, Frost free from May 25 to September 8 +/-