Prepare soil by digging deeply, pulverizing, and compacting. Ensure it is well-draining, loose, and has a slightly acidic to neutral pH (optimum 6.2 to 6.8).
Tip: Blend in aged manure or compost before planting.
2
Plant onion sets 1 to 2 inches deep with the pointy ends facing up.
Tip: Plant 2 to 4 weeks before the last frost date.
3
Space sets 3 to 4 inches apart for large bulbs (or 2 inches for smaller bulbs) in rows 12 to 18 inches apart.
4
Cover the space between planting rows with a layer of straw mulch to stifle weeds.
5
Water weekly if weather is dry to provide consistent moisture for the shallow root systems.
Tip: Water early in the day to avoid wetting foliage and prevent disease.
6
Perform regular weeding by hand if weeds are close to the rows.
Tip: Eliminate weeds to improve air circulation.
7
Avoid covering growing onions with additional soil, as this can interfere with the bulbing process.
8
Practice plant sanitation by removing affected plant parts when not wet.
Tip: Discard all fallen or diseased leaves and bulbs in autumn.
9
Monitor maturity; storage varieties typically take 90 to 110 days to mature.
10
Harvest bulbs once they have reached maturity.
Pro Tips
The more energy onions get from the sun, the larger their bulbs will grow.
Large bulbs (more than 1/2 inch) are more prone to bolting.
Sweet or milder varieties do not store well and should be eaten soon after harvest.