New England’s largest greenhouse is growing more than tomatoes – it’s growing jobs. Maine Gov. John Baldacci picked several tomatoes off the vine on Tuesday at a celebration of the first harvest at a huge new greenhouse in Madison. Backyard Farms this summer completed construction of an 18-acre glass-covered greenhouse, giving it two greenhouses covering a total of 42 acres with 450,000 tomato plants. For its new greenhouse, the company hired about 75 workers over the summer, expanding its work force to about 200 employees. Backyard Farms harvested its first tomatoes in 2007 and has now sold about 40 million pounds to stores across the Northeast.