Roma tomatoes are a hybrid variety developed around 1955, and are believed to be a cross of the Pan American tomato with San Marzano, a paste tomato that was thought to have been brought into the United States by Italian immigrants. Roma tomatoes were bred specifically for their shape, disease resistance, and durability. With such qualities, the Roma tomato has been widely adapted throughout the United States, and does well against diseases common in cool, wet climates. However, too cold of soil and air temperatures can stress tomatoes plants, so it is crucial to plant outside only after the final frost.