Growing Giant Onions: Sets vs. Sprouted Bulbs

Softball-sized onions come from planting small, dormant "sets" in early spring. If you're trying to regrow last year's sprouted onions, they'll only swell slightly—they've already used their energy to produce a flower stalk. For maximum size, start fresh with sets or transplants each season. Plant in loose, fertile soil, keep weed-free, and fertilize regularly. The biggest onions need a long, cool growing period to bulb up before summer heat triggers maturity.