Thank you for all the comments. Appreciate it. By morning my greenhouse was actually 6 degrees warmer than outside temp so I was feeling happier. Also realized our outside thermometer is on a brick wall that warms all day long so it takes it longer to drop temperature. That probably explains why it took until very late for the GH to register a bit warmer than the outside temp. It did warm up very quickly to 85 In the GH today which was nice since it took it all day to get to 69 outside.
Tonight I have a 65 watt bulb in there and loosely wrapped the mylar blankets to see if any warmth bounces off them onto the plants. It will be even colder tonight at 42 so will see how it does. Kind of looks like a space ship all lighted up in the dark. I will have to work up something better before winter freezes. Also discovered we have a bunch of old fashioned Chrisrmas lights. Will be interesting to experiment with those too. Want to see what makes the most difference before we are hit by an actual frost. Will keep eyes open for one of those solar blankets.
Thanks again for all the comments.
