The 'Sweet Spanish' onion was grown in the U.S. at least as far back as 1916. 'Yellow Sweet Spanish Utah' is from that early type, producing large, 3"-6" globe-shaped bulbs with amazingly mild, sweet flavor. A long-day variety, it grows best in states north of the 37th parallel. Utah designated this onion the state vegetable in 2002. Caramelize onions for the perfect patty melt condiment.