How to Grow Onion

Intermediate

Allium cepa

A long-season bulb crop grown from sets or seed. Harvest when tops fall over and begin to dry.

Last updated: June 2026

Days to Maturity

100–120 days

typical

Per Square Foot

Plant Spacing

10 cm / 4"

Sun

6+ hours

Water

1.0" / 25 mm

Fertilization

moderate feeder

Growing Notes

Plant sets in early spring as soon as soil is workable. Start from seed indoors 10–12 weeks before last frost.

Varieties & Cultivars

13 cultivars in our database. Click any card to see growing details.

Sweet

(4)

Candy

85–100 days Hybrid

intermediate-day type; mild; stores 3-4 months

Height: 12–18" (30–46 cm)
Yield / plant: —
Avg fruit: 8.8 oz (250 g)
Support: none
Harvest: once
USDA Zones: 3–10
Seed saving: difficult
Seed viability: 1 years

Cipollini

75–90 days Open-Pollinated

excellent caramelized or roasted

Height: 12–18" (30–46 cm)
Yield / plant: —
Avg fruit: 2.8 oz (80 g)
Support: none
Harvest: once
USDA Zones: 3–10
Seed saving: difficult
Seed viability: 1 years

Texas 1015

100–115 days Open-Pollinated

short-day type; poor storage

Height: 12–18" (30–46 cm)
Yield / plant: —
Avg fruit: 12.3 oz (350 g)
Support: none
Harvest: once
USDA Zones: 3–10
Seed saving: difficult
Seed viability: 1 years

Walla Walla

90–115 days Open-Pollinated

not a good keeper; long-day type

Height: 12–18" (30–46 cm)
Yield / plant: —
Avg fruit: 9.9 oz (280 g)
Support: none
Harvest: once
USDA Zones: 3–10
Seed saving: difficult
Seed viability: 1 years

Large sweet yellow onion

(1)

Yellow Spanish

110–130 days Open-Pollinated

mild flavour; good for fresh eating; short-day variety; stores moderately

Height: 6–8" (15–20 cm)
Yield / plant: —
Avg fruit: 6.3 oz (180 g)
Support: none
Harvest: once
USDA Zones: 4–10
Seed saving: easy
Seed viability: 1 years

Large white onion

(1)

White Sweet Spanish

110–130 days Open-Pollinated

thin skin; excellent fresh; short-day variety; popular in Southwest

Height: 6–8" (15–20 cm)
Yield / plant: —
Avg fruit: 7.1 oz (200 g)
Support: none
Harvest: once
USDA Zones: 4–10
Seed saving: easy
Seed viability: 1 years

Red onion for warm climates

(1)

Red Creole

100–120 days Open-Pollinated

good colour retention; short-day variety; good for Southern gardens

Height: 6–8" (15–20 cm)
Yield / plant: —
Avg fruit: 4.9 oz (140 g)
Support: none
Harvest: once
USDA Zones: 5–10
Seed saving: easy
Seed viability: 1 years

Scallion

(2)

Evergreen Bunching

60–80 days Open-Pollinated

produces white slender stalks year-round; divides readily; extremely cold-hardy; harvest outer stalks and leave clump to regrow; Japanese heirloom

Height: 12–18" (30–46 cm)
Yield / plant: —
Avg fruit: 0.7 oz (20 g)
Support: none
Harvest: cut-and-come-again
USDA Zones: 3–10
Seed saving: difficult
Seed viability: 1 years

White Lisbon

60–80 days Open-Pollinated

Height: 12–16" (30–41 cm)
Yield / plant: —
Avg fruit: 1.1 oz (30 g)
Support: none
Harvest: once
USDA Zones: 3–10
Seed saving: difficult
Seed viability: 1 years

Scottish heirloom

(1)

Ailsa Craig

105–120 days Open-Pollinated

translucent flesh; mild flavour; excellent for pickling; day-neutral

Height: 6–8" (15–20 cm)
Yield / plant: —
Avg fruit: 5.6 oz (160 g)
Support: none
Harvest: once
USDA Zones: 4–9
Seed saving: easy
Seed viability: 1 years

Storage

(3)

Red Baron

100–115 days Open-Pollinated

Height: 12–18" (30–46 cm)
Yield / plant: —
Avg fruit: 5.3 oz (150 g)
Support: none
Harvest: once
USDA Zones: 3–9
Seed saving: difficult
Seed viability: 1 years

Stuttgarter

90–110 days Open-Pollinated

strong pungent flavour; excellent storage; sets available

Height: 12–18" (30–46 cm)
Yield / plant: —
Avg fruit: 3.9 oz (110 g)
Support: none
Harvest: once
USDA Zones: 3–10
Seed saving: difficult
Seed viability: 1 years

Yellow Globe

100–115 days Open-Pollinated

pungent flavour; stores 6+ months

Height: 12–18" (30–46 cm)
Yield / plant: —
Avg fruit: 5.3 oz (150 g)
Support: none
Harvest: once
USDA Zones: 3–10
Seed saving: difficult
Seed viability: 1 years

Companion Planting

What to grow alongside onion, and what to keep apart.

Plant With

Spinach : Onion scent deters pests from spinach

Brussels Sprouts : Onion scent deters cabbage moths and aphids from brussels sprouts

Beet : Onion scent deters beet pests

Celery : Onion scent deters celery leaf miners

Turnip : Turnip roots loosen soil; onions deter turnip pests

Leek : Fellow alliums share pest-deterrent properties and growing conditions

Rhubarb : Onions deter pests from rhubarb; complementary root depths

Cabbage : Onions repel cabbage maggots and loopers

Kale : Onions deter cabbage pests from kale

Broccoli : Onions repel brassica pests

Lettuce : Onion scent deters aphids from lettuce

Pepper : Onions deter aphids from peppers

Carrot : Onion scent deters carrot rust fly; carrot scent deters onion fly

Strawberry : Onion scent deters aphids and spider mites from strawberries

Swiss Chard : Onion scent deters pests from chard

Dill : Dill attracts pollinators near onion plants

Cauliflower : Onions repel cabbage pests from cauliflower

Keep Apart

Beans : Onions inhibit bean growth through root exudates

Peas : Onions inhibit pea growth

Asparagus : Onions compete for nutrients and may inhibit asparagus root growth

Square Foot Spacing

9 per sq ft

4" apart (3×3 grid)

View full spacing chart →

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