What Grows in Boulder, CO?
Boulder's mountain proximity creates complex microclimates — valleys are warm while higher areas are cold.
Zone
Last frost
First frost
Frost-free days
Boulder is in USDA Zone 5b with about 145 frost-free days, and you can grow tomatoes, peppers, root vegetables, brassicas, and more here.
Planting tips for Boulder
Watch for late-season cold snaps. Walls and south-facing beds create warm microclimates.
What to plant, and when
Timing by your frost dates — last frost May 5, first frost September 30.
Tomato, Cherry Tomato, Bell Pepper, Chili Pepper, Cucumber, Zucchini, Eggplant, Pumpkin
Lettuce, Spinach, Kale, Broccoli, Carrot, Radish, Beets, Onion
Green Beans, Potato, Sweet Potato, Corn, Microgreens, Rhubarb
Garlic
What grows well in Boulder
Tomato
Grows well
Cherry Tomato
Grows well
Bell Pepper
Grows well
Chili Pepper
Grows well
Cucumber
Grows well
Zucchini
Grows well
Green Beans
Grows well
Lettuce
Grows well
Spinach
Grows well
Kale
Grows well
Broccoli
Grows well
Carrot
Grows well
Radish
Grows well
Beets
Grows well
Onion
Grows well
Garlic
Grows well
Potato
Grows well
Sweet Potato
Grows well
Corn
Grows well
Peas
Grows well
Cabbage
Grows well
Brussels Sprouts
Grows well
Eggplant
Grows well
Swiss Chard
Grows well
Arugula
Grows well
Microgreens
Grows well
Pumpkin
Grows well
Leek
Grows well
Asparagus
Grows well
Rhubarb
Grows wellFrequently asked questions
What hardiness zone is Boulder, CO in?
Boulder, CO is in USDA Hardiness Zone 5b. This drives everything about what you can reliably grow — it maps directly to how cold your winters get.
When is the last frost in Boulder?
The average last spring frost in Boulder is around May 5, and the first fall frost is typically September 30. Plan to move tender plants outside after May 5 and have them harvested (or protected) before September 30.
What grows well in Boulder?
Plenty — Boulder's USDA Zone 5b climate supports 30+ crops. Some of the easiest and most reliable here are Cherry Tomato, Chili Pepper, Cucumber.
How long is Boulder's growing season?
Boulder typically has around 145 frost-free days per year (roughly May 5 to September 30). That's a full season — plenty of time for most annual vegetables plus a succession or fall crop of cool-season greens.
What should I plant first in Boulder?
Go with fast-maturing crops to get a quick win while the season is short: Microgreens, Arugula, Radish are among the quickest from seed to harvest in Boulder.
Can I grow vegetables in containers in Boulder?
Yes — Boulder's climate is container-friendly for the right crops. Tomato, Cherry Tomato, Bell Pepper all do well in pots, which also lets you start them a little earlier and move them in on cold nights.
When should I start seeds indoors in Boulder?
For warm-season crops like Tomato, Cherry Tomato, Bell Pepper, start seeds indoors 6–8 weeks before your last frost (around May 5), then transplant after the danger of frost has passed.