When to Plant Tomatoes in Gilliam 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.
Gilliam County, Oregon is in USDA Zone 6a. The average last spring frost is April 25 and the first fall frost is October 15, giving you a growing season of approximately 173 days.
At an elevation of 965 feet, Gilliam County receives approximately 22.4 inches of rainfall annually with predominantly silt loam soil. Summer highs average 85°F, providing good warmth for Tomatoes during the growing season.
Gilliam County Soil Profile
Soil Type
Silt Loam
Soil pH
5.3-6.7
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.
Soil Compatibility in Gilliam County
How your county's soil matches Tomatoes's growing requirements.
Soil pH
Your soil pH (5.3–6.7) overlaps with Tomatoes's range (6.0–7.0), though not a perfect match.
Soil Texture
The silt loam soil in Gilliam County is excellent for Tomatoes — good drainage, moisture retention, and nutrient holding capacity.
Drainage
Drainage is adequate for Tomatoes.
Organic Matter
Organic matter is excellent (4.5%) — Tomatoes will thrive.
How to Plant Tomatoes
Succession Planting Tomatoes
Sow every 6.9 weeks. Last sowing by Jul 22 to harvest before frost.
Plant Water Budget
Monthly Watering Guide for Tomatoes
Tomatoes needs approximately 1.2 inches of water per week (5.2" per month). Here's how your county's rainfall compares month by month.
| Month | Tomatoes Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 2.8" | 0" | ❄️ Dormant |
| Feb | — | 2.8" | 0" | ❄️ Dormant |
| Mar | — | 2.4" | 0" | ❄️ Dormant |
| Apr | 5.2" | 1.4" | 3.8" | 🚿 Regular watering |
| May | 5.2" | 1.4" | 3.8" | 🚿 Regular watering |
| Jun | 5.2" | 0.8" | 4.4" | 🚿 Regular watering |
| Jul | 5.2" | 0.3" | 4.9" | 🚿 Regular watering |
| Aug | 5.2" | 0.5" | 4.7" | 🚿 Regular watering |
| Sep | 5.2" | 0.9" | 4.3" | 🚿 Regular watering |
| Oct | 5.2" | 1.7" | 3.5" | 🚿 Regular watering |
| Nov | — | 3.7" | 0" | ❄️ Dormant |
| Dec | — | 3.8" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Gilliam County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Tomatoes Heat Requirements (GDD)
What are Growing Degree Days (GDD)?
Growing Degree Days measure the total warmth your plants receive during the growing season. Think of it as a "heat bank" — every day above 50°F deposits warmth that helps your plants grow.
Each plant needs a certain amount of accumulated heat to mature. If your county provides more GDD than the plant needs, it's a great fit. If it's close, you may want to choose faster-maturing varieties or start seeds indoors to get a head start.
Tomatoes Planting Timeline — Gilliam County, OR
Tomatoes Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | February 28 | Feb 28 – Mar 14 |
| Transplant Outdoors | May 9 | May 9 – May 23 |
| Direct Sow | May 2 | May 2 – May 23 |
| Harvest | July 11 | Jul 11 – Sep 19 |
Plant 0.5" deep · 24" apart · Rows 36" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | Start Indoors |
| March | Start Indoors |
| April | — |
| May | Transplant Outdoors Direct Sow |
| June | — |
| July | Harvest |
| August | Harvest |
| September | Harvest |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
1.2"/week · 2-3 times/week
📅 Days to Maturity
60–85 days
🧪 Soil pH
Needs 6–7 · Your soil: acceptable
🗺️ USDA Zone
Zone 6a
📆 Growing Season
173 days in Gilliam County
Growing Tips for Tomatoes in Gilliam County
Direct sow Tomatoes outdoors after April 25 in Gilliam County when soil has warmed and frost danger has passed.
Common pests for Tomatoes in this region include tomato hornworm and aphids. Use row covers early in the season and inspect plants weekly.
Gilliam County receives only 22" of rain annually. Tomatoes needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.
General growing tips
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
Check more plant combinations with our Companion Planting Checker →
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 Gilliam County, OR?
Gilliam County is in Zone 6a with an average last frost of April 25. Plan your Tomatoes planting based on this frost date — see the calendar above for exact timing.
What planting zone is Gilliam County, OR?
Gilliam County, Oregon is in USDA Hardiness Zone 6a. The average last spring frost is April 25 and first fall frost is October 15.
Plan Your Garden with Confidence
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