Yellow Sweet Spanish onion forms yellow-skinned bulbs up to 5 inches wide for fall curing and cool storage. Sow seeds 1/4 inch deep, 1 to 3 seeds per inch, then thin to 2 to 6 inches apart; start indoors 8 to 10 weeks before last frost or sow outside after soil reaches 55 degrees.
Seed sprouts in 5 to 10 days in 60 to 75-degree soil. Purchase fresh seed each season, since allium germination tested rates fall fast.
