What can you do when you have already planted tomatoes in your garden and you notice that the forecasted overnight low is going to get dangerously close to freezing?
Cover them! The ground around the tomatoes will still be warm with the heat absorbed from the sun all week. Even if the ground is 50 degrees, it will still radiate this heat all night. If you cover the tomatoes as this heat rises, you can capture it and contain it to keep the plants a few degrees warmer than the outside air.
You can also put jugs or buckets of hot water under the cover, as long as you as sure they won’t tip over and burn the tomato roots. This will probably help a lot.
Here are a couple pictures of my scrounged tomato covers from last weekend:
Lovely, right? Yes, the first one is a soccer net, covered with a used plastic painting tarp and some camping sheets (that I had just washed, gosh!)