Question: We are looking for advice as to when is the best time to transplant tomato seedlings into our UNHEATED 50-ft tunnel. We are in Androscoggin County (5b). Answer: Abi Griffith, Horticulture Community Education Assistant Generally, you can transplant tunnel tomatoes about a month earlier than you would do field tomatoes. So if your seedlings read more When is the best time to transplant tomatoes into an unheated tunnel?