When to Plant Watermelon in Routt County, CO
Watermelon is a sprawling vine crop that produces sweet, juicy fruits in hot weather. Varieties range from personal-sized icebox types to 50-pound giants.
Routt County, Colorado is in USDA Zone 4a. The average last spring frost is June 12 and the first fall frost is September 8, giving you a growing season of approximately 88 days.
At an elevation of 5,381 feet, Routt County receives approximately 24.5 inches of rainfall annually with predominantly loam soil. Summer highs average 83°F, so choose short-season varieties of Watermelon to ensure they mature before fall.
Routt County Soil Profile
Soil Type
Loam
Soil pH
6.7-7.9
Drainage
Well Drained
Plant Planting Risk Windows
Percentages indicate frost risk at transplant. The 70% safe window means there is a 30% chance of frost after transplant — suitable for cold-hardy crops or gardeners with frost protection. The 90% safe window is best for tender plants.
Plant Water Budget
Water stress score is 6/10 — consider drought-tolerant varieties and mulching
Watermelon Planting Timeline — Routt County, CO
Watermelon Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | May 1 | May 1 – May 15 |
| Transplant Outdoors | July 3 | Jul 3 – Jul 17 |
| Direct Sow | June 26 | Jun 26 – Jul 17 |
| Harvest | September 11 | Sep 11 – Oct 30 |
Plant 1" deep · 30" apart · Rows 42" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | — |
| May | Start Indoors |
| June | Direct Sow |
| July | Transplant Outdoors Direct Sow |
| August | — |
| September | Harvest |
| October | Harvest |
| November | — |
| December | — |
Growing Conditions
Sun
Full Sun (6-8+ hours)
Water
Moderate — regular watering
Days to Maturity
70–100 days
Soil pH
6 – 7.5
USDA Zone
Zone 4a
Growing Season
88 days
Growing Tips for Routt County
Start seeds indoors 3-4 weeks early or direct sow after soil is warm. Plant on mounds with plenty of space. Check ripeness by looking for a yellow ground spot and dull thump when tapped.
Companion Planting
Good Companions
Avoid Planting Near
Level Up Your Garden
Watermelon in Other Locations
Frequently Asked Questions
When should I plant Watermelon in Routt County, CO?
Routt County is in Zone 4a with an average last frost of June 12. Plan your Watermelon planting based on this frost date — see the calendar above for exact timing.
What planting zone is Routt County, CO?
Routt County, Colorado is in USDA Hardiness Zone 4a. The average last spring frost is June 12 and first fall frost is September 8.
Plan Your Garden with Confidence
Get our free Garden Planner — designed to help Routt County gardeners in Zone 4a organize planting dates, track what's growing, and never miss a planting window.
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