When to Plant Tomatoes in Big Horn County, WY
Tomatoes are the most popular home garden crop, available in thousands of varieties from tiny cherries to massive beefsteaks. They are warm-season plants needing full sun.
Big Horn County, Wyoming is in USDA Zone 4a. The average last spring frost is May 9 and the first fall frost is October 2, giving you a growing season of approximately 146 days.
At an elevation of 7,668 feet, Big Horn County receives approximately 13.7 inches of rainfall annually with predominantly loam soil. Summer highs average 84°F, so choose short-season varieties of Tomatoes to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Tomatoes successfully. Mulch heavily to conserve soil moisture.
Big Horn County Soil Profile
Soil Type
Loam
Soil pH
6.2-7.7
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 8/10 — consider drought-tolerant varieties and mulching
Tomatoes Planting Timeline — Big Horn County, WY
Tomatoes Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 7 | Mar 7 – Mar 21 |
| Transplant Outdoors | May 30 | May 30 – Jun 13 |
| Direct Sow | May 23 | May 23 – Jun 13 |
| Harvest | August 1 | Aug 1 – Oct 10 |
Plant 0.5" deep · 24" apart · Rows 36" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | — |
| May | Transplant Outdoors Direct Sow |
| June | Transplant Outdoors Direct Sow |
| July | — |
| August | Harvest |
| September | Harvest |
| October | Harvest |
| November | — |
| December | — |
Growing Conditions
Sun
Full Sun (6-8+ hours)
Water
Moderate — regular watering
Days to Maturity
60–85 days
Soil pH
6 – 7
USDA Zone
Zone 4a
Growing Season
146 days
Growing Tips for Big Horn County
Start seeds indoors 6-8 weeks before last frost. Bury transplants deep to encourage rooting along the stem. Provide consistent moisture to prevent blossom end rot and cracking.
Companion Planting
Good Companions
Avoid Planting Near
Level Up Your Garden
Isolate 25 ft between varieties for purity. Use open-pollinated varieties for true-to-type seeds.
Tomatoes in Other Locations
Frequently Asked Questions
When should I plant Tomatoes in Big Horn County, WY?
Big Horn County is in Zone 4a with an average last frost of May 9. Plan your Tomatoes planting based on this frost date — see the calendar above for exact timing.
What planting zone is Big Horn County, WY?
Big Horn County, Wyoming is in USDA Hardiness Zone 4a. The average last spring frost is May 9 and first fall frost is October 2.
Plan Your Garden with Confidence
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