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What Can Grow in Boulder, CO

Boulder's mountain proximity creates complex microclimates — valleys are warm while higher areas are cold.

Boulder, CO is in USDA Hardiness Zone 5b. The growing season lasts about 145 days, with last frost around May 5 and first fall frost around September 30. Top crops include tomatoes, peppers, root vegetables.

5bUSDA Zone
145 daysFrost-Free
May 5Last Frost
September 30First Frost
🌱 What Grows in Boulder
tomatoespeppersroot vegetablesbrassicasherbsbeans
💡 Planting Tips

Watch for late-season cold snaps. Walls and south-facing beds create warm microclimates.

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🔗 More Resources
📍 Full Zone 5b Guide 🌎 Colorado Planting Guide

Frequently Asked Questions

Boulder, CO is in USDA Plant Hardiness Zone 5b. Boulder's mountain proximity creates complex microclimates — valleys are warm while higher areas are cold.

The average last spring frost in Boulder is around May 5. The first fall frost typically arrives around September 30, giving a frost-free growing season of approximately 145 days.

Boulder's Zone 5b climate supports growing tomatoes, peppers, root vegetables, brassicas, herbs, beans. Watch for late-season cold snaps. Walls and south-facing beds create warm microclimates.

In Boulder, start with cool-season crops like lettuce, spinach, and broccoli a few weeks before the last frost date of May 5. Warm-season crops like tomatoes and peppers should go in after all frost risk has passed.