Saffron -- "the world's most valuable spice" -- has advantages as "a
crop harvested in the late fall, when other crops have died off, that
tolerates extreme climates and yields an average of $19 per gram."
"UVM [University of Vermont] researchers said the yields amounted to $4.03 a square foot, compared to $3.51 a square
foot for tomatoes, and $1.81 a square foot for winter leafy greens. They estimate an acre of saffron grown in high tunnelscould bring in $100,000 a season."