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When to Plant Tomatoes in Wasco County, OR

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.

Wasco County, Oregon is in USDA Zone 6b. The average last spring frost is April 23 and the first fall frost is October 12, giving you a growing season of approximately 172 days.

At an elevation of 432 feet, Wasco County receives approximately 35.5 inches of rainfall annually with predominantly silt loam soil. Summer highs average 80ยฐF, so choose short-season varieties of Tomatoes to ensure they mature before fall.

Wasco County, OR (Zone 6b) Moderate season
172 days
Last Spring Frost April 23
172 growing days
First Fall Frost October 12

Wasco County Soil Profile

Soil Type

Silt Loam

Soil pH

5.2-6.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (27 days to spare)
Start indoors: Feb 17 Transplant: Apr 28 🍅 Harvest: Jun 30 – Sep 8
Recommended (50%) ✓ Fits season (25 days to spare)
Start indoors: Feb 26 Transplant: May 7 🍅 Harvest: Jul 9 – Sep 17
Safe Start (90%) ✓ Fits season (22 days to spare)
Start indoors: Mar 18 Transplant: May 27 🍅 Harvest: Jul 29 – Oct 7

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

Plant needs
1.0″/week
Rainfall provides
0.9″/week
You supply
0.1″/week
Watering frequency Only during dry spells
Season total 204 gal / 100 sq ft
Tomatoes needs ~725 GDD — county provides 1,720 GDD Excellent fit

Tomatoes Planting Timeline โ€” Wasco County, OR

Tomatoes Planting Calendar

Activity When Date Range
Start Indoors February 26 Feb 26 โ€“ Mar 12
Transplant Outdoors May 7 May 7 โ€“ May 21
Direct Sow April 30 Apr 30 โ€“ May 21
Harvest July 9 Jul 9 โ€“ Sep 17

Plant 0.5" deep ยท 24" apart ยท Rows 36" apart

Month-by-Month Timeline

MonthActivities
January โ€”
February Start Indoors
March Start Indoors
April Direct Sow
May Transplant Outdoors Direct Sow
June โ€”
July Harvest
August Harvest
September Harvest
October โ€”
November โ€”
December โ€”

Growing Conditions

Sun

Full Sun (6-8+ hours)

Water

Moderate โ€” regular watering

Days to Maturity

60โ€“85 days

Soil pH

6 โ€“ 7

USDA Zone

Zone 6b

Growing Season

172 days

Growing Tips for Wasco 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

  • Cabbage
  • Fennel
  • Potatoes

Level Up Your Garden

๐ŸŒพ Save Your Own Tomatoes Seeds
Life Cycle Annual
Pollination Self-Pollinating
How to Collect Scoop seeds from ripe fruit; ferment 2-3 days to remove gel coating.
Storage Store airtight; viable 4-6 years at 35ยฐF, under 45% humidity.

Isolate 25 ft between varieties for purity. Use open-pollinated varieties for true-to-type seeds.

Frequently Asked Questions

When should I plant Tomatoes in Wasco County, OR?

Wasco County is in Zone 6b with an average last frost of April 23. Plan your Tomatoes planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Wasco County, OR?

Wasco County, Oregon is in USDA Hardiness Zone 6b. The average last spring frost is April 23 and first fall frost is October 12.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Wasco County gardeners in Zone 6b organize planting dates, track what's growing, and never miss a planting window.

Get Your Free Garden Planner →

Free download. Plan your entire garden season in minutes.

Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Wasco County, OR. Local conditions may vary. Last updated: April 2026.