Seed Needs, Utah Yellow Sweet Spanish Onion (Allium cepa) 450 Seeds Non-GMO Quality Yellow Spanish Onion seeds packaged by Seed Needs. Each Package displays a colorful illustration on the front side, as well as detailed sowing instructions on the reverse side. Utah, Yellow Sweet Spanish will produce jumbo sized bulbs that range in weight from 10 ounces to 1 pound. Yellow Sweet Spanish will be ready for harvesting in roughly 110 days after sowing. Onions will grow in a single growing season, from seed to harvest and can be started indoors or outdoors. All Onion seeds sold by Seed Needs are Non-GMO based seed products and are intended for the current & the following growing season. All seeds are produced from open pollinated plants, stored in a temperature controlled facility and constantly moved out due to popularity.