>>1297598A good tunnel system is priceless for colder areas. Although, this was the 1st year frost occurred inside the tunnels one morning. It was the tunnel with the highest level of soil inside, but didn't have black painted 2-liter soda bottles full of water in it for extra thermal mass. Most of the plants suffered, but I only lost some squash type plants. All the tomato plants recovered, but were set back by about a week.
For plants like peppers, that are shorter when fully grown, I put the tunnels back over them in the fall to keep them going as long as possible. Sometimes I put 2 layers of plastic over it. Each layer is like warming it up to 1 temperature zone warmer. I think the soda bottles add 1 more zone too, if the tunnel is full of them.
>pic from last spring before a hard frost the next morning May 8th. Tomato plants were 2 feet tall then? 