Broccoli
What Plant Yet? knows about broccoli, and where each number comes from. For today's answer, pick your town.
Planting numbers
- Frost category
- Hardy Source: Colorado State University Extension
- Plant outdoors
- 2–4 weeks before typical last frost Given for hardy crops as a group. Source: Colorado State University Extension
- Start seeds indoors
- 6–8 weeks before typical last frost Source: Colorado State University Extension
- Cover at or below
- 28°F Source: Utah State University Extension
- Grows once daytime temperatures reach
- 40°F Given for hardy crops as a group. Source: Colorado State University Extension
- Days to harvest
- 65 Source: Colorado State University Extension
Left out because we found no university extension source for it: minimum night temperature. We don't estimate.
Growing tips
- Use transplants in spring; the seed dislikes cold soil. (Colorado State University Extension)
- For the best-quality crop on the Front Range, direct-seed in early July for fall harvest. (Colorado State University Extension)
- Choose young transplants: about four inches tall and four weeks old. (Colorado State University Extension)
- Long, hot summer days make broccoli bolt. (Colorado State University Extension)
- For cabbageworms, spray Bt in the evening because sunlight breaks it down quickly. (Colorado State University Extension)
How the answer uses this
The planting window opens 2–4 weeks before typical last frost in your town and stays open while a planting still has 65 days to mature before the typical first fall frost. Inside the window the answer is Plant when the coldest of the next 7 nights stays above 28°F (no source gives a minimum night temperature, so the cold-damage temperature is used). Cover tonight shows when tonight's low is 28°F or colder while broccoli is normally in the ground.
Sources
- Colorado State University Extension — checked Nov 11, 2026
- Colorado State University Extension — checked Nov 11, 2026
- Utah State University Extension — checked Nov 11, 2026
- Colorado State University Extension — checked Nov 11, 2026
Guidance only. Extension advice is written for typical conditions; your soil, variety and microclimate matter.