When to Plant Onion in Colorado Springs, Colorado (80938)
Location
Colorado Springs, Colorado
ZIP Code
80938
USDA Zone
6a
Last Frost
Monday, April 20, 2026
📅 Planting Calendar
Start Seeds Indoors Monday, February 23, 2026
Transplant Outdoors Monday, May 4, 2026
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
Mature Height 12-18"
Spread 4"
Type Bulb
Fruit Size Medium (2-4 inch bulb)
☀️ Growing Requirements
☀️
Sun
Full Sun (6+ hours)
💧
Water
Moderate
↔️
Spacing
4" apart
🌱
Planting Depth
0.5" deep
Seeds typically germinate in 7-10 days
🤝 Good Companions
CarrotBeetLettuceTomatoBrassicas
⚠️ Avoid Planting Near
BeanPeaAsparagus
Other Plants for Colorado Springs
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
Growing Onion in Zone 6a
Onion (Allium cepa) is a popular garden vegetable. In Colorado Springs, Colorado, which is in USDA Hardiness Zone 6a, you should start seeds indoors around Monday, February 23, 2026.
Your average last frost date is Monday, April 20, 2026. Plan to transplant your Onion seedlings outdoors around Monday, May 4, 2026, about 2 weeks after your last frost date.