Red Onion

Red Onion is the sharp, colorful cooking onion with deep purple-red skin and crisp white flesh ringed in purple. Raw, it brings color and bite to salads, salsas, and sandwiches; roasted or caramelized it turns sweet and mellow. Most red onions sold for the North are long-day storage types that bulb when summer days stretch past about 14 hours, while short-day reds are grown in the South, so matching the variety to your latitude is the key to getting full-size bulbs. It is a cool-season crop planted in early spring and harvested in mid to late summer.

✅ Plant alongside

Good neighbors that attract beneficial insects or deter pests

• Carrots — Onion scent masks carrots from the carrot rust fly
• Beets — Benefit from onion pest-deterrent effect
• Chamomile — Reputed to improve onion flavor and vigor
• Summer Savory — Deters onion flies and bean beetles

❌ Keep away from

🛡️ Pest & disease prevention

Proactive ways to stop trouble before it starts — tap a name with an arrow for its full guide

• Onion thrips →

  Keep plants vigorous and well-watered; use reflective mulch to disorient thrips; remove debris after harvest

• Onion maggot →

  Rotate alliums to a new bed each year; use floating row cover at planting

• Downy mildew →

  Space for airflow; avoid overhead watering; plant in well-drained soil

🌾 Harvest & storage

Harvest when about half the tops have fallen over naturally, bending any stubborn upright ones down to stop further leaf growth. Loosen the bulbs and let them dry, then cure in a warm, dry, airy spot at 75 to 90F for two to four weeks until the necks are tight and the skins papery. Clip the tops and roots after curing. Red onions store for roughly two to three months in a cool, dry place, a shorter shelf life than yellow storage onions, so use them first.

🥗 Nutrition & benefits

Red onions are rich in quercetin and the anthocyanin pigments that give the skin its color, both antioxidants linked to reduced inflammation and better cardiovascular health. They are a good source of vitamin C and supply prebiotic fiber that feeds beneficial gut bacteria. Low in calories, they add big flavor for little energy, and much of the antioxidant value sits in the outer layers, so peel sparingly.