Subway operates over 37,000 restaurants across the world. This means that there are many, many kitchens that have to be kept fully stocked with fresh ingredients, including lettuce. Many Subway menu items, such as wraps, salads, and sandwiches, contain lettuce, so it's an item that's in high demand.
In fact, there's so much demand for lettuce that Subway reckons it gets through 4 ha of the leafy vegetable every day, according to a Twitter post from the chain. That equals roughly 12 football fields.
Investing in lettuce has helped Subway grow some impressively big returns: The restaurant chain's 20,000-plus US stores create $9.4 billion of annual revenue. However, Subway's lettuce usage has taken a hit in Australia, where supplies have been hit by crop destruction and rising prices. As a consequence, Subway has been mixing lettuce with cabbage to prevent supplies from completely running out.
Source: mashed.com