🥕 Onion

Allium cepa

vegetables bulb vegetable (allium)

☀️ Sun

Full sun (6–8+ hours); day length triggers bulbing — choose correct variety for your latitude (short-day for south, long-day for north)

💧 Water

Medium; 1 inch per week; consistent moisture during bulbing; reduce/stop watering when tops begin to fall over to promote curing

🗺️ Zones

3, 4, 5, 6, 7, 8, 9, 10

🪴 Soil Type

Well-drained, fertile loam with moderate organic matter; lighter soils produce better bulbs; heavy clay can cause thick necks and poor storage

🧪 Soil pH

6.0–7.0 (slightly acidic to neutral)

💧 Drainage

Good drainage critical; onions rot in waterlogged soil; raised beds recommended in clay soils

📏 Spacing

Sets/plants 4–6 inches apart in rows 12–18 inches apart; close spacing produces smaller bulbs; wider spacing for large slicing onions

📅 Days to Maturity

90-150 days (from transplant/sets); 100-175 days from seed depending on day-length type

🍴 Edible Parts

🍽️ ["Bulb"🍽️ "Green tops (scallions/green onions)"🍽️ "Flower stalks (scapes \u2014 milder than bulb)"]

🤝 Companions (8)

🤝 Carrot

Onions repel carrot rust fly; carrots deter onion fly — classic and highly effective mutual pest-repelling partnership; probably the most proven companion planting combination

🤝 Chamomile

Improves onion flavor and growth; antifungal properties may reduce onion diseases; attracts beneficial insects

🤝 Beet

Onions repel many beet pests; beets grow at different root depth; complementary growth habits

🤝 Strawberry

Onions repel slugs and many strawberry pests; strawberries act as living mulch

🤝 Lettuce

Lettuce grows quickly in the space between onions; onions repel lettuce pests like aphids and slugs

🤝 Tomato

Onions repel spider mites and aphids from tomatoes; though alliums are less effective near solanaceous crops than near carrots

🤝 Summer Savory

Improves onion growth and flavor

🤝 Beet

Beets and onions are a classic companion pair: onions deter pests from beets while beets help break up soil for onion bulbs. Almanac notes improved onion seed yield when grown near beets.

⚠️ Keep Apart (3)

⚠️ Bean (all types)

Alliums inhibit Rhizobium bacteria — beans will be stunted if planted near onions; one of the strongest documented antagonisms

⚠️ Pea

Same reason as beans — alliums inhibit nitrogen-fixing bacteria crucial for legumes

⚠️ Sage

May stunt onion growth; aromatic incompatibility (some sources report mutual antagonism)

💊 Medicinal Uses

["Contains allicin and quercetin \u2014 antimicrobial, anti-inflammatory, and antioxidant compounds", "Traditionally used for colds, flu, and respiratory infections; may reduce blood pressure and cholesterol", "Contains prebiotic fibers (inulin) supporting gut microbiome", "Topical: onion juice used traditionally for wound healing, ear infections, and insect stings"]

📝 Notes

Day length determines bulbing: short-day onions (10-12 hrs daylight) for zones 7+, long-day (14-16 hrs) for zones 6 and colder. Onions can be grown from seeds, sets (small bulbs), or transplants. Cure after harvest: dry in warm, ventilated area for 2-3 weeks until necks are tight and dry. Store in cool, dark, dry place (not refrigerator). Never plant onions where any Allium has grown in 3+ years.