When to Plant Tomatoes in Wyoming
Published: April 21, 2026
Wyoming gardeners in Zone 6a have a 31-week growing season for tomato (March 30 to November 1). The moderate climate supports a full warm-season crop plus an often-productive fall crop. This guide gives exact dates for Wyoming based on your local frost calendar.
Tomato Planting Dates for Wyoming
| Start seeds indoors | February 16–23 |
| Last frost (average) | March 30 |
| Transplant outdoors | April 13–23 |
| Expect first harvest | June 12 – July 7 |
| Fall crop start | August 9–19 |
| Fall harvest | October 8 |
| First fall frost (average) | November 1 |
⚠ Warm-climate gardeners (TX, FL, AZ) can grow TWO crops: spring (Feb–March transplant) and fall (July transplant for October harvest).
Growing Tomatoes in Wyoming's Climate
Wyoming's moderate Zone 6a climate is well-suited to tomato with minimal special accommodation. The standard transplant calendar works as written, and harvest windows line up with what seed packets recommend without adjustment.
Succession planting extends your tomato harvest significantly in Wyoming. A second planting 3 to 4 weeks after the first gives you a backup in case of pest pressure and extends the total harvest window into early fall.
Common tomato pests to watch for in Wyoming include Tomato Hornworm and Aphids. The first line of defense is companion planting: Basil and Marigold planted nearby discourage several of these pests by confusing host-plant identification or repelling adults before they can lay eggs. Weekly garden walks in the early morning catch problems when they're still manageable.
Tomato Garden Calendar for Wyoming
| Month | Task | Notes |
|---|---|---|
| January | — | Dormant season |
| February | Start seeds indoors | Use grow lights; warm soil to 70–75°F for best germination |
| March | Harden off seedlings | Set seedlings outdoors 1–2 hours daily, increasing gradually |
| April | Transplant outdoors | Soil temp must be 60°F+; nighttime lows above 50°F |
| May ← | — | Dormant season |
| June | Peak growth; water 1 inch/week | Monitor for pests daily; stake or support as needed |
| July | Start fall crop seeds | Fall transplants go in 12 weeks before first frost |
| August | Fall crop planting | Transplant or direct sow for fall harvest before frost |
| September | — | Dormant season |
| October | — | Dormant season |
| November | First frost approaches | Harvest remaining tomato; cover plants on frost nights |
| December | — | Dormant season |
Tomato Growing Tips for Wyoming Gardeners
- •Bury the stem 2/3 deep when transplanting — roots grow from the buried stem for a stronger plant.
- •Consistent watering prevents blossom end rot and fruit cracking; uneven moisture causes both.
- •Wyoming's moderate climate supports succession planting — sow new transplants or seeds every 3 weeks during spring to extend the harvest window into fall.
- •Stop heavy nitrogen once flowers appear — it causes leafy plants with few tomatoes.
Companion Planting for Tomatoes in Wyoming
In Wyoming's moderate climate, planting tomato with Basil and Marigold helps deter pests and improve soil. Avoid planting near Potato and Fennel, which inhibit tomato growth through root chemistry or shared pest pressure. See the full tomato companion planting guide for the complete list.
Frequently Asked Questions
When should I plant tomato in Wyoming?
In Wyoming (Zone 6a), start tomato seeds indoors around February 16–23 and transplant outdoors around April 13–23 — 2 weeks after the state's average last frost of March 30.
What is the last frost date in Wyoming?
Wyoming's average last frost date is March 30 in the state's most common Zone 6a. Frost dates vary by city — higher elevations and northern counties run 1 to 3 weeks later than the state average. See the city list below for city-level frost dates.
Can I grow tomato year-round in Wyoming?
Not year-round — Wyoming's cold season stops tomato production. The tomato season runs March 30 to November 1, roughly 31 weeks. A fall crop extends harvest into late autumn.
What tomato varieties grow best in Wyoming?
For Wyoming's Zone 6a, Classic mid-season varieties like Better Boy, Big Beef, and Roma perform well across most conditions.
When do I start tomato seeds indoors in Wyoming?
Start tomato seeds indoors in Wyoming around February 16–23, which is 6 weeks before the state's average last frost of March 30. Use grow lights and keep soil temperatures at 70–75°F for fastest germination.