Watermelon
What Plant Yet? knows about watermelon, and where each number comes from. For today's answer, pick your town.
Planting numbers
- Frost category
- Very tender Source: Colorado State University Extension
- Plant outdoors
- 2 weeks after typical last frost Given for very tender crops as a group. Source: Colorado State University Extension
- Start seeds indoors
- 2–3 weeks before planting out Source: Colorado State University Extension
- Cover at or below
- 32°F Given for very tender crops as a group. Source: Utah State University Extension
- Grows once daytime temperatures reach
- 60°F Given for very tender crops as a group. Source: Colorado State University Extension
- Days to harvest
- 80–95 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
- Needs a long, warm season; most productive below about 5,000 feet elevation in Colorado. (Colorado State University Extension)
- Judge ripeness by thumping or by a buttery-yellow ground spot. (Colorado State University Extension)
- Plant when soil is 65°F or after all frost danger has passed. (Utah State University Extension)
- Afternoon wilting is normal; plants still wilted in the morning need water. (Colorado State University Extension)
- Pick only when fully ripe. (Colorado State University Extension)
How the answer uses this
The planting window opens 2 weeks after typical last frost in your town and stays open while a planting still has 95 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 32°F (no source gives a minimum night temperature, so the cold-damage temperature is used). Cover tonight shows when tonight's low is 32°F or colder while watermelon is normally in the ground.
Sources
- Colorado State University Extension — checked Nov 11, 2026
- Utah State University Extension — checked Nov 11, 2026
- Colorado State University Extension — checked Nov 11, 2026
- Utah State University Extension — checked Nov 11, 2026
Guidance only. Extension advice is written for typical conditions; your soil, variety and microclimate matter.