You should never use plastic to cover a plant. Use a blanket or a sheet and tie it so it doesn't get blown off. I grew one from seed this year. I found out later you need to to get them to fruit. They look like they would be very sensitive to frost. Is this a normal time for you to get frost? We don't get frost until November. We make a small make shift greenhouse and installed an old electric heater to save our Golden Jubilee tomatoes. It worked. It was only a little taller than the plants. I saved corn one year by covering them with blankets. Tomatillos seem like they would need more than that.

Perhaps I should have noted, plastic supported by #9 wires, kind-of like a mini greenhouse. The forecast is actually for 34 degrees but it is a new garden and I am not familiar with where all of the cold zones are, yet.

Zackey, I also thought you needed two to get fruit. I had read that both ways were true.
Alas! I had a volunteer show up this year (3 years after I had a plant with very little fruit) and it is LOADED with fruit! Ya never know!!!! Nancy

I have had tomatillos survive light frosts quite well.