🌱 MyLocalPlanting

When to Plant Onion in Zone 12A

USDA Zone

12A

Cities Covered

25

Avg Last Frost

Friday, January 1, 2027

Plant Type

Indoor Start

📅 Planting Calendar for Zone 12A

Start Seeds Indoors Friday, November 6, 2026
Transplant Outdoors Friday, January 15, 2027

Pro Tip: Start Onion seeds indoors 8 weeks before your last frost date for best results.

🌿 Plant Details

Scientific Name Allium cepa
Days to Maturity 100 days
Sun Requirements Full Sun (6+ hours)
Plant Spacing 4" apart

Cities in Zone 12A

Aiea, Hawaii Anahola, Hawaii Haiku, Hawaii Hanalei, Hawaii Waikoloa, Hawaii Kalaheo, Hawaii Kapaa, Hawaii Kualapuu, Hawaii Kunia, Hawaii Kurtistown, Hawaii Lawai, Hawaii Lihue, Hawaii Makawao, Hawaii Makaweli, Hawaii Papaikou, Hawaii Pearl City, Hawaii Wahiawa, Hawaii Pukalani, Hawaii Mililani, Hawaii Kula, Hawaii Waialua, Hawaii Waipahu, Hawaii Wheeler Army Airfield, Hawaii Schofield Barracks, Hawaii Camp H M Smith, Hawaii

Other Plants for Zone 12A

Blackberry Blueberry Raspberry Strawberry Basil Chamomile Chives Cilantro Dill Lavender Lemon Balm Marjoram Mint Oregano Parsley Rosemary Sage Tarragon Thyme Acorn Squash Artichoke Arugula Asparagus Beefsteak Tomato Beet Bell Pepper Bok Choy Broccoli Brussel Sprout Butternut Squash Cabbage Cantaloupe Carrot Cauliflower Cayenne Pepper Celery Cherry Tomato Chili Pepper Collard Green Common Bean Cucumber Eggplant Endive Fennel Garlic Grape Tomato Green Bean Habanero Pepper Head Lettuce Heirloom Tomato Honeydew Melon Jalapeño Pepper Kale Kohlrabi Leaf Lettuce Leek Lima Bean Mustard Okra Parsnip Pea Poblano Pepper Pole Pea Potato Pumpkin Radicchio Radish Rhubarb Roma Tomato Rutabaga Serrano Pepper Shallot Snap Pea Snow Pea Spaghetti Squash Spinach Squash Sweet Corn Sweet Potato Swiss Chard Tomato Turnip Watermelon Zucchini

Browse Other Zones

Zone 1a Zone 1b Zone 2a Zone 2b Zone 3a Zone 3b Zone 4a Zone 4b Zone 5a Zone 5b Zone 6a Zone 6b Zone 7a Zone 7b Zone 8a Zone 8b Zone 9a Zone 9b Zone 10a Zone 10b Zone 11a Zone 11b Zone 12b Zone 13a

Growing Onion in USDA Zone 12A

Onion (Allium cepa) grows well in USDA Hardiness Zone 12A. This zone includes cities like Aiea, Anahola, Haiku and 22 more.

The average last frost date for Zone 12A is around Friday, January 1, 2027. For best results, start your Onion seeds indoors around Friday, November 6, 2026, then transplant outdoors around Friday, January 15, 2027.

Expect to harvest your Onion approximately 100 days after planting.