Spinach
What Plant Yet? knows about spinach, 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
- 5–6 weeks before planting out Source: Utah State University Extension
- Cover at or below
- 28°F Source: Oregon 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
- 40 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
- Never let it dry out, or leaves turn tough and stringy. (Colorado State University Extension)
- Sow in mid-fall and mulch seedlings for an extra-early spring crop. (Colorado State University Extension)
- Aim for fast growth that finishes before summer heat. (Utah State University Extension)
- Seed can go in once soil reaches 40°F. (Utah State University Extension)
- Thin seedlings so plants are not competing for water, light and nutrients. (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 40 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 spinach is normally in the ground.
Sources
- Colorado State University Extension — checked Nov 11, 2026
- Utah State University Extension — checked Nov 11, 2026
- Oregon 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.